Re: [AMRadio] Ham Radio Growing in the Age of Twitter
Here is the link to the ATC article. Interestingly, the photo on the ATC web page shows a real homebrew amateur radio station from 1939, not a ricebox station full of plastic radios or a shack-on-a-belt. http://www.npr.org/templates/story/story.php?storyId=125586086 __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Ham Radio Growing in the Age of Twitter
Here is the link to the ATC article. Interestingly, the photo on the ATC web page shows a real homebrew amateur radio station from 1939, not a ricebox station full of plastic radios or a shack-on-a-belt. http://www.npr.org/templates/story/story.php?storyId=125586086 __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] SDR IQ
I wouldn't want to try to dive into a laptop and replace the sound card. To me, the innards of a laptop are close to the same as the innards of a ladies' swiss watch. But there are high end outboard card cards on the market that simply plug into a USB port. __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] SDR IQ
I wouldn't want to try to dive into a laptop and replace the sound card. To me, the innards of a laptop are close to the same as the innards of a ladies' swiss watch. But there are high end outboard card cards on the market that simply plug into a USB port. __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] More buzzies and hash
Nothing is going to happen. The government is broke, local, state and feds. The FCC has under 3000 people doing everything, and most are legal types I think. Do you expect the feds to check EVERY gizmo coming into the country for noise and design issues, and check that they don't 'forget' to put the filters in once its type accepted, or whatever? They wouldn't have to check every gizmo, but if the appropriate standards are in place and the manufacturers/importers are made aware of them, once they begin spewing out their electromagnetic hash or toxic substances, the victims of the pollution have a right to expect the FCC or other appropriate agency to enforce its rules and issue cease and desist orders against the offending device. A few significant fines would cover the cost of enforcement action. Those companies have a lot deeper pockets than do a few renegade chickenbanders and their ilk. By the same logic, rules and laws already on the books should be able to better protect the public from such things as toxic paint on Chinese toys than has been reported recently. Agreed that the govenrment is bankrupt, so they would have no business spending scarce funds on things like enacting a ban on AM in the first place, while existing laws and regulations that would actually serve the public interest, remain unenforced. DC __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[AMRadio] Tube Tester Question (TV7D/U)
My mutual conductance tester TV7D/U has a gas test function. The way the manual explains its function is that the tube is set up with a fixed plate voltage, and when you press the Gas 1 button, a negative bias is applied to the grid, and you manually use the bias pot to adjust this voltage until the plate current deflects the meter to the first large division (10 on the 0-120 scale). Then, while holding down the Gas 1 button, you simultaneously press the Gas 2 button. This inserts 80,000Ω in series with the grid. If the tube is gassy, it will draw a small amount of grid current which will cause the bias voltage to decrease, due to voltage drop in the series resistor. This reduction in negative bias voltage causes the plate current to increase. The manual recommends that a tube be discarded as gassy if the plate current increases by more than 10%, that is to say, if the meter increases more than one small division. My question is, what if the pointer deflects downwards when the Gas 2 button is pressed? I see it deflect downwards far more often than upwards, and with some tubes the decrease is several small divisions. If the tube is free of gas, shouldn't it remain still? Nothing in the manual mentions the possibility that the plate current might decrease when the resistor is inserted in the grid circuit. There is no such thing as negative gas in a tube, but it would seem that if inserting resistance into the grid circuit causes the plate current to change in either direction, this could be a problem, since it is very common to have 80k or more resistance in the grid circuit of a tube type amplifier, particularly with R-C coupling. What could be the cause of a decrease in plate current, other than a small contact potential bias, which should be thoroughly swamped out by the external fixed bias in this test circuit? I am aware that sometimes a triode amplifier that is designed to handle a very low signal level, such as a microphone pre-amp, may have no cathode resistor, and depends on contact potential to generate a fraction of a volt negative bias to operate the tube. But in these circuit, there is usually several megohms of grid resistance. I always thought of this as a rather flaky way to generate the operating bias for a tube, but I am not even sure this has anything to do with the above described phenomenon. Don k4kyv __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [AMRadio] Comment from N0JE
I read an article about AM use in the ham bands in a recent QST magazine and was intrigued. The article even gave the favorite AM freqs. I have a 200 watt AM transceiver so I wanted to give it a go on 80 meters. Problem is, it seems no one even cares to listen to see if anyone wants to join in. The people just short key it back and forth passing it between the click of regulars and never seem to open it up to see if anyone new wants to join in. Very frustrating. You don't have to wait to break in to an existing QSO. Why not find a clear spot nearby, put your rig into AM mode, call CQ 75 metres AM phone, and start your own QSO? I tend to shy away from QSOs with more than 3 or 4 participants. Better to start a new group than to endure a roundtable consisting of 8 or 9 stations, where you wait patiently for 45 minutes or more between transmissions, and no-one comments on anything anyone else says, because it has been so long since they heard it that they don't remember. Sometimes AM groups can be heard using fast break-in, but with PTT instead of VOX. This is usually within a group of friends who know each other, and can be chaotic and difficult for newcomers to join in. Those suggested AM frequencies in the article are just that - suggestions. Your licence allows you to operate AM anywhere in the band that it is legal for you to operate SSB. Just make sure that the frequency is clear before firing up. Don k4kyv __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[AMRadio] QST AM Article and SSB Power
The article Why Not Give AM a Try that appeared in February QST (p. 43) points out a not-so-well-known fact that will undoubtedly be overlooked by most readers: (Quote) Power level Your 100 W SSB transceiver puts out 100 W PEP on SSB. That is, at the peak of your voice envelope the power output is 100 W, just as it can be 100 W with your key down on CW. When you're not talking on SSB, your power output is 0 W. The actual average output is typically less than 10W, depending on voice characteristics. (end quote) Of course, this is in reference to a good quality SSB voice signal that is not over-driving the rig or linear amp, and is not overly processed. At the 10w level, on an amplifier capable of 100 watts peak, the amplitude of the signal voltage is running at just 31.6% of the amplifier's peak capability. The amplifier is running at 1/10 of its peak power capability, and since power is a function of the square of signal voltage, the output voltage is 1/√10= 1/3.1623 = .316 or 31.6% of the peak voltage capability. If you ever watched the analogue VU meters at a recording studio or broadcast station, you might have noticed that when a person is talking, the meter hovers at about the -10 VU or 30% modulation level, even though it may kick up towards 0 VU (100% modulation) on occasional peaks. With music and other program material, it may run much higher. So, the average power output level of a linear amplifier running SSB is actually less than the unmodulated carrier power of that same amplifier running AM at the same peak power level, and the SSB efficiency is averaging considerably less than when the amplifier is running AM. The difference is not so obvious, because with AM, the carrier operates at a continuous 100% duty cycle, while with SSB, the power output is intermittent, running at a very low duty cycle, but the meters kick up to maximum on voice peaks while the meter stands still when the amplifier is operated properly on AM. So much for the alleged inefficiency of a linear amplifier when it is used to run AM. This means that at 1500 watts pep output, the average output power of a SSB transmitter should not exceed about 150 watts. Therefore, the p.e.p. power limit penalised SSB just as much or even more so than it did AM, assuming that the SSB transmitter is run cleanly and properly. Under the old DC input rule, a linear could be run up to where the meters indicated a kilowatt DC average input, with the peaks allowed to go as high as the headroom of the amplifier permitted. Amplifiers in the 50's-70's were universally touted in the ads as capable of 2000 watts (pep in tiny letters) input. By running the linear at higher peak power, the clean SSB output power could be legally run considerably higher than it can under the present rules. How many of the slopbucket linears you hear on the air these days are really operated within that power limitation? Now, explain that to the next slopbucketeer you hear P M'ing that AM'ers run illegal power. (Unfortunately, the concept will probably go right over his thick head.) __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: AMRadio@mailman.qth.net To unsubscribe, send an email to amradio-requ...@mailman.qth.net with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[AMRadio] Re: AM BANDWARMING
So far, the specific frequencies I have heard mentioned are: 3610, 3650 and 3685. Any others? How many separate frequencies should we attempt? I think we should try for four in the new Extra class segment. This should be well decided and publicised days in advance of the opening moment. I have to get up at 5:20 Friday morning. Plan to take a nap Thursday evening after dinner and get up in time for the initial band opening at 12:01 AM, but I probably won't try to stay on for more than an hour. Friday evening should be interesting. Let's see if there are any SSB jammers. Shouldn't be, since there will be more than enough room on the band for everyone. Are any specific frequencies being planned for the Advanced and General segments? Generals will have access to the vicinity of 3825, where there already is AM activity regularly in late afternoon/early evening hours, as well as the longstanding Canadian AM frequency of 3725, which will be open to Advanced and Extra. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ _ View Athletes Collections with Live Search http://sportmaps.live.com/index.html?source=hmemailtaglinenov06FORM=MGAC01 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] RE: AMRadio Digest, Vol 34, Issue 47
On 11/21/06, Albert Santangelo [EMAIL PROTECTED] wrote: I won't have any problem welcoming the US AM ops..they're not the problem..its all the other garbage/SSB qrm games..etc..that will follow. If that becomes intolerable on 3725, maybe your group could QSY down to somewhere just below 3700, which will be limited to Extra class only, so there should be less US garbage/SSB qrm games..etc. The old 3675-3725 US novice segment will be relocated to 3525-3600. I suspect that after the initial novelty wears off, the 3600-3700 segment will be even more sparcely populated by US stations on phone than it now is with CW/RTTY/digital. There are plenty of arse-holes on the air in the US with Advanced-class tickets. Don k4kyv _ Get free, personalized commercial-free online radio with MSN Radio powered by Pandora http://radio.msn.com/?icid=T002MSN03A07001 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: AM BANDWARMING
I suspect some readers may have misinterpreted this thread, so let's clarify the issue. We are not talking about setting up new AM windows, but agreeing upon WHERE TO MEET ON THE 15TH OF DECEMBER for the initial bandwarming. I believe it would be highly desirable to hit the ground running by immediately establishing several AM QSO's, spaced uniformly throughout the new Extra Class segment, as well as in the Advanced and General class segments, and we should all be aware and agree on approximately where we will meet that night. The idea is to occupy several frequencies throughout the new allocations, and for each station to hop between these QSO's, so that the entire AM presence on the new frequencies doesn't end up on one frequency in one huge roundtable. Better to keep each group limited in size to 3 or 4 participants at most, and for each participant to shuffle from one AM group to another throughout the early morning and evening of the 15th. The idea is to make an impressive showing the first hours of the expanded phone band with AM presence scattered uniformly throughout. If the AM groups all grow in size beyond 3 or 4 participants, then find a clear spot somewhere and call CQ. In the weeks to follow, habitual operating frequencies by all users will fall into place naturally. What we want to avoid is merely setting up one or two clones of the existing AM Window somewhere lower in the band, or worst of all, after a few weeks, all the AM activity drifting back to 3880-90. Don, k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ _ Get free, personalized commercial-free online radio with MSN Radio powered by Pandora http://radio.msn.com/?icid=T002MSN03A07001 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] AM BANDWARMING
I'm hearing more and more Extra class AM'ers expressing their intent to appear on 3600-3700 the minute the expanded phone band opens on the 15th of December. Frequencies I hear discussed are 3685, and down on the low end near 3610. No need for everyone to congregate on one frequency. Why not make it a point to start up right away on several frequencies spread uniformly throughout the band, and each station periodically shift around from one QSO to another, so that all the QSO frequencies remain in use into the wee hours, but allowing everyone to participate in the QSO on each of the frequencies. Let's make it more like the etiquette of a successful house party. Instead of everyone standing around the entire evening confined to one small group, be sociable and continue circulating from one group to another for the duration. WATSA y'all? You got less than a month to upgrade to Extra if necessary, and to get the rig and antenna tuned up and working on the low end of the band! Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ _ Get free, personalized commercial-free online radio with MSN Radio powered by Pandora http://radio.msn.com/?icid=T002MSN03A07001 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: AM BANDWARMING
The time is Friday 15DE06 at 12:01 Eastern Standard Time. That's 0501 GMT, or 9:01 PM PST. It would had been better of they had given the time in GMT to avoid confusion. Better still, they could have made it 0001 GMT, which would have opened up the band 5 hours earlier. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ _ MSN Shopping has everything on your holiday list. Get expert picks by style, age, and price. Try it! http://shopping.msn.com/content/shp/?ctId=8000,ptnrid=176,ptnrdata=200601tcode=wlmtagline __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] 813 filament voltage
Running a thoriated tungsten filament tube at too low filament voltage wil shorten the life of the tube more than running it at too high voltage. The manufacturers say keep it within +/- 5% for optimum tube life. It can safely be run at slightly reduced voltage as long as there is NO reduction in the peak emission during normal operating conditions. If the filament voltage is reduced enough to starve the electron stream, this will destroy the molecules-thick coating of thorium on the surface of the tungsten filament and the tube will go flat. In an effort to prolong tube life, some broadcast engineers reduce voltage until a reduction in peak output is just barely noticed, then the voltage is slightly increased beyond the point that restores full peak emission. But this requires very careful monitoring of both filament voltage and peak output. A weak tube may be brought brought back up to full output for a limited period by increasing filament voltage above normal. This is not recommended for a good tube. RCA says it's ok to reduce the filament voltage to 80% normal during STAND-BY periods (zero cathode current). Don k4kyv _ Use your PC to make calls at very low rates https://voiceoam.pcs.v2s.live.com/partnerredirect.aspx __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Why it is good to have a basement awash in parts
Better to have it and not need it, than to need it and not have it. -John W5MEU (SK) _ Get today's hot entertainment gossip http://movies.msn.com/movies/hotgossip?icid=T002MSN03A07001 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] BC610 110v using one leg of 2207
From: Jim candela [EMAIL PROTECTED] I am talking about a simple auto-transformer to transform 220 down to 110 vac. Using this method you can pull power from both HOT legs of your 220, and not worry about whether that 3rd wire is a ground or neutral, or what gauge wire that wire is. Some 3-wire cable designed for 220 volts only has a smaller neutral wire than the 2 hot wires. If you are going to pull 110 off the neutral and one hot, you need to be sure that the 3 conductors are the same gauge. Otherwise, the voltage will sag under load on one side of the line while the voltage will increase on the opposite side. This could damage certain equipment and could even be a safety hazard. Also, make sure the 3rd wire really is a neutral, not just a safety ground. The safety ground might not be wired directly to the neutral wire at the fuse box with a connection designed to pull the same current as the hot wires. I have a large 220-110v stepdown Sola transformer, and it gives better regulation out to the exterior shack, than using one of the 110 volt circuits directly. It also provides some isolation against rf crud on the line. However, I am not presently using it. One problem I have with this method is leaving the tranformer in line unattended all the time. It could become a fire hazard in the event one of the windings in the transformer develops shorted turns, or the transformer is zapped with lightning. I have seen the major mess that resulted from a power transformer burn-out in a tube-type stereo amplifier that happened to be left on all night. I could imagine what would have happened if that had been a multi-kva transformer instead of a small power transformer. Maybe the transformer could be mounted in a fire-proof case or metal rack away from flammable material, but there would still be the possibility of smoke damage from burnt tar and paper inside the transformer. Transformers, even hermetically sealed ones, will often produce a lot of smoke before the fuse blows (if there is one). Don k4kyv _ Get today's hot entertainment gossip http://movies.msn.com/movies/hotgossip?icid=T002MSN03A07001 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Zero beating
From: Todd, KA1KAQ [EMAIL PROTECTED] Another side of it though, is the SSB stations who zero-beat an AM qso and interfere that way. Had several doing this last week. So some of the guys tune just slightly off one way or the other, to make this a less-desirable option. But we're talking a few cycles, not 5-6 kcs. Sure, they can notch out the main carrier, but notching out several slightly different ones isn't quite as easy. From what I heard last night, the increase in phone spectrum won't stop the few lids who want to intentionally interfere. They sought out AMers no matter where they went. It's not a space issue for them, it's a poor attitude and minimal (if any) education. Then the slopbuckets intentionally zero in on the AM carriers, it's time for the old tactic Timtron calls exit stage left. Otherwise, I agree it's good practice for everyone in a QSO to stay zero beat. My only problem is that with some antennas, the VFO signal isn't strong enough to hear in the rx and I have to temporarily switch to a different antenna while zero-beating. With the advent of transceivers, many of the newer hams don't have a clue to the concept of zero-beating. Don k4kyv __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Phone band expansion
If AM is getting so popular, why aren't there any manufacturers producing any equipment? Where have you been the past 20+ years? Nearly all HF transceivers made to-day include true double-sideband full carrier AM mode, along with SSB, CW and various digital capabilities. There aren't any major manufacturers producing HF rigs that are AM-only for exactly the same reason they aren't producing SSB-only or CW only rigs. (I'm not talking about little single-mode QRP kits.) Don k4kyv __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Phone band expansion
Up to an extra 150 kc/s for phone on 75 m for Extra class. 75m Phone Allocations General Advanced Extra Current 3850-4000 3775-4000 3750-4000 New 3800-4000 3700-4000 3600-4000 Increase 50 75150 40m Phone Allocations General Advanced Extra Current 7225-73007150-73007150-7300 New 7175-73007125-73007125-7300 Increase5025 25 Much better than anything I had anticipated, but we are still left with a cumbersome matrix of subbands based on operator class combined with emission mode. Considering the relief in congestion we have already experienced due to the general decline in amateur activity in recent years, there should be plenty of room for all on 75m, without the griping about AM taking up too much room on the crowded band. Of course, if the FCC eventually eliminates the code requirement, expect an initial spike in activity as hoards of no-code Techs upgrade, but after the initial spike I predict a return to stagnant growth. There should still be plenty of room for AM activity. Once the expansion goes into effect, we should immediately commence AM activity on the new frequencies, including the 3600-3700 kc/s Extra segment. I have looked over the R O, but I am not sure if it means that 3600-3700 is restricted to Extra class for all modes, or just that Extras can now use phone in the segment. How this will affect non-voice licence class restrictions is not made entirely clear in the FCC document: 12. Regarding the division among license classes of the spectrum on which we today authorize phone emissions, we adopt the Commissions proposal to authorize stations of General Class licensees to transmit voice emissions in the 3800-4000 kHz frequency segment, thereby increasing by 50 kHz the spectrum for voice communications by these stations. Because we have decided to authorize more 75 m spectrum for voice communications than was proposed in the NPRM, we also authorize stations of Advanced Class licensees to transmit voice emissions in the 3700-4000 kHz frequency segment, thereby increasing by 75 kHz the amount of spectrum for voice communications by these stations. We also authorize stations of Amateur Extra Class licensees to transmit voice emissions in the 3600-4000 kHz frequency segment, thereby increasing by 150 kHz the spectrum authorized to these stations for voice communications. In the 40 m and 15 m bands, we adopt the Commissions proposal to authorize stations of Amateur Extra and Advanced Class licensees 7125-7300 kHz, stations of General Class licensees 7175-7300 kHz, and stations of General Class licensees 21275-21450 kHz for phone communications. If Generals and above will still be able to use 3600-3700 for non-voice modes, expect digital modes to continue to operate in this segment. I suspect that may be the reason such a big hunk was set aside for Extras - to limit phone activity in that region of the band so that some of the digital stuff can continue on those frequencies. Although the thinking of government agencies is extremely unpredictable, this doesn't look well for the ARRL's bandwidth proposal. If the FCC were seriously considering limitations by bandwidth any time soon, it is unlikely they would have gone to all the trouble to work out this plan, only to have to revise it in the near future to accomodate subbands-by-bandwidth. Looks like we'll soon be able to join the Canadians in their AM Window on 3720. The change is expected to go into effect sometime in mid-November. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-06-149A1.pdf ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Phone band expansion
When the phone band expands, there will be plenty of room below 3800 to operate. I suggest somewhere lower in the band, towards 3700. Also, extras will be able to go on down to 3600. As quiet is the present 3750-3775 is most of time, I doubt if 3600-3700 will be jam-packed with signals anytime soon. The 3790-3800 DX window will likely remain active to accomodate Generals, who will operate split and transmit just above 3800. Even now advanced can go down to 3775 and extras to 3750, but the window remains at 3790. I am all for imposing AM presence anywhere in the band we can legally operate, but no point in deliberately kicking a wasp nest. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: Vintage recordings and preservation
A friend of mine had some tapes of WA5FHP in DeQuincy, LA who was on 3950 kHz AM as late as the early 1980's. I wish a thousand times I had made tapes of the AM diehards here in the southeast, like K4AGY,W4AGX,WA4PQH,W4ZWE and others such as Don K4KYV in the late 1960's and early 1970's when I was getting into ham radio. Otis and Ozona Bob were regulars then, too. Joe W4AAB Or Con and Walt recordings of the 1964-65 era. I recall in the old Ham Trader Yellow Sheets someone, in Nashville I believe, used to regularly advertise want-ads for anyone who had any of those. ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Residual Magnatism
I have had that problem with DC relays, but never with ac ones. The magnetic field produced by the a.c. voltage should de-gauss the core, just like a tape de-gausser demagnetises recording tape. A tape de-gausser is nothing but a large coil with 60~ a.c. applied. The worst relays I have encountered with the sticking problem were dc ones, salvaged from ARC-5's and other command sets. I have had limited success with a tape shim stuck across the pole piece. I often operate 110 volt a.c. relays with about 32 volts DC. I have heard of residual magnetism being a problem when running ac relays on DC, but I have never had any problem with mine. If that ever does get to be a problem, perhaps an easy solution would be to periodically reverse the polarity of the dc voltage to the coil whenever the relay starts to stick. I haven't used a Dow-key relay for antenna changeover since my Gates transmitter turned one into a solid block of charcoal. I do use a bunch of smaller ones, built very similar to miniature Dow-keys but with BNC connectors and 28 vdc coils, for switching the VFO between transmitters, and for switching amongst receiving antennas. They were made for military/industrial use and I suspect they originally cost a mint. They have been extremely reliable for me ever since I picked them up in the mid 70's; don't recall if they were in some of the stuff I once pulled out of a dumpster on the Harvard University campus, or if I found them in some odd junk I bought at a hamfest. Don k4kyv __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] You can't always trust those free online translators
Sometimes those translators don't work out exactly as you would think. Let's try a little experiment. 1. Open the following page: http://translation2.paralink.com/ 2. Choose English-Russian translation and paste the following text into the appropriate field: I think we should use CW and the time for best propagation would be 1145 GMT. Press the Translate button to get the result. 3. Now copy the Russian translation of the text. 4. Select Russian-English translation. Paste the Russian text into the appropriate field. Press the Translate button to get the result when your translation is converted back into English. :-) Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: Meter help
Try using a jeweller's screwdriver to turn the tiny screws. They're cheap. You can pick up a complete set of screwdrivers for a few bucks. Some manufacturers used some sort of gunk that looks like tar to seat the heads of the screws. Try exposing the heads of the screws and heating them using the tip of a small soldering iron. Sometimes that will free them up. If the screw is corroded into the metal insert, or even bakelite case, a tiny drop of Liquid Wrench will sometimes do the trick. The most stubborn ones I have encountered is with antique meters - early 30's or older - where the back of the case is made of pot metal. I have had hunks of the meter case actually break off when I finally got enough of a grip on the screw to make it turn. ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Question for K4KYV
I am not Don, but since he hasn't answered, I remember he found a filter at some surplus place in the Washington, D.C area back several years ago. Seems like the cutoff was 3400 Hz on the nose. Not a very expensive part then, but IIRC fron his post of this last year, there are unobtainum now. Joe W4AAB That is correct. I found the filter in 1973. I have seen ones similar to it, but always with a different cutoff frequency. But I think there are circuits available today for simple solid state active filters that would be just as good. I preceed the filter with a pre-emphasis circuit that begins a presence rise at about 800~, and steadily rises up to about 8 dB at 3000~, and then cuts off sharply at 3400~. Two microphones are used, in phase and mixed together. An electrovoice dynamic with crapped out high frequency response is used with a D-104, using a homebrew two-channel audio mixer with the pre-emphasis curve on the D-104. I paid only a few bucks for that filter in Washington DC. If I had known how good it was, I would have bought every one they had. I think they had about half a dozen in stock. I have a second filter with about a 5000~ cutoff, much more gradual, that in switchable with the 3400~ one. I use it when the band is less crowded and the other person can open up the selectivity. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Collins Filter ID Needed
Trying to identify this filter: F 455 K 160. 455 kHz i.f, 16 kHz bandwidth. the K indicates the physical construction (type of input and output leads, physical shape and size, mounting configuration, etc). The last number in the filter type number is the selectivity X 10. http://www.wa3key.com/filters.html#list
Re: [AMRadio] UPS Shipping
That's because the warehouse guys pick a couple packages to play football with and yours might be one of them... Shipping boatanchors via UPS is like playing Russian roulette. I used to service electronic equipment at the American Airlines terminal at Logan Airport in Boston. One of the machines I serviced was located in the luggage handling area. It was not unusual to see guys come in ticked off by something and grab a suitcase and slam it on the floor, or kick a piece of luggage off the conveyor belt and then stomp it with all their might. I suspect UPS workers are no different. Don k4kyv
Re: [AMRadio] fs: Delta ASM-1
From: david knepper [EMAIL PROTECTED] Jim, I would highly recommend going to a lumber yard (Home Depot) and buy a sheet of styrofoam insulation board. Cut and form around the unit to be shipped. Or wrap the unit in several layers of plastic wrap, then use aeorsol spray foam caulking like Great Stuff as packing material. You need to be familiar with how it expands so that you get the foam to just barely fill the box after it expands. It is somewhat of a pain to remove the item from the foam at the receiving end, but a very secure method of packing. Just be sure the equipment is well wrapped so that the liquid foam doesn't contact the item being shipped, since that could do severe damage. I would recommend buying an extra can and practising first with a spare cardboard box and some useless junk to get the hang of it. I have received a couple of items thru UPS that were packed using this method, and there was no damage. The foam absorbs the shock while making it impossible for the contents to shift around inside the box. First, spray foam into the bottom of the box, allow it to expand for a few minutes, then set the wrapped item on the foam, fill in the sides, and finally the top. One word of caution - the liquid foam can be extremely messy, so do the packing in an appropriate area. Don k4kyv
RE: [AMRadio] Nonsense from Russia
From: Mark Foltarz [EMAIL PROTECTED] Did anyone else get this ? $52 ?!? Who are they kidding? Hey, I just came upon a large sum of money, but it is located in Nigeria. Wanna help me get it out of the country? I'll give you a cut. Pse reply by e-mail... Urgently! Oh, BTW, I'll need your SS#, ATM PIN #, and credit card # to verify the deal. Don k4kyv
Re: [AMRadio] Re: Value of Homebrew Rigs, WAS: Stuff for sale...update.
I know one prior owner in the Milwaukee area who traded his KW-1 for a house-painting job. I asked him why and he said I needed the house painted ;-) This was back in the 70s when all he figured if it was just useful for CW or as a linear, he could do that with a much smaller rig. Yeah, he's still kicking himself! Well, I dunno. Even at today's KW-1 prices, that might not be such a bad deal. Have you seen any estimates on house painting lately? Even a moderately sized house with wood siding may run into 5 digits these days for a good professionally done job. Don k4kyv
Re: [AMRadio] Re: Value of Homebrew Rigs, WAS: Stuff for sale...update.
From: Todd, KA1KAQ [EMAIL PROTECTED] But then -- you wouldn't be a member of the small group running a KW-1. It would be nice if more of the collector-owners would actually fire them up. I'm a firm believer that bragging rights for a strapping signal far outweigh those of a pretty box. There are a number here on the east coast that can be heard regularly. I recall in the 1980's, before they started to bring in such big bux, there must have been over a dozen KW-1's on the air regularly. There were several lists of all the known serial #'s. IIRC, more than half the ones ever made were still in existence and accounted for. Then the owners began to see offers they couldn't refuse, and since then, most have disappeared off the air and into trophy rooms. Quite a few have gone to collectors in Europe and Asia. Don k4kyv
Re: [AMRadio] Re: WRL Globe King 500C rebuild
In the stock transmitter, the final amplifier plate voltage is 1800 volts, so the 2000 volts shouldn't cause too much of a problem. The modulator originally ran only 1200 volts on the plates of a pair of 811A's, and the modulation transformer was just barely step-down, with a turns ratio of something like 1.15:1. Even so, the modulator would just barely make about 85% modulation in most transmitters, if you were lucky. Running 2 kv on both with a common power supply should give better modulation, but the final tank cap might arc over on modulation peaks. This is assuming that the G-C driver stage is capable of fully driving the modulator at the increased plate voltage. With a common power supply, the modulation transformer should have turns ratio of about 1.4 or 1.5 to 1. The 572B's MIGHT work OK with the stock audio driver and mod transformer. Don k4kyv
Re: [AMRadio] FW: Request for HAM Radio Operator
From: david knepper [EMAIL PROTECTED] I am getting a message from Paypal that I have some undisclosed activity. It has a box that I am to click on to acess my accont. Of course, I do not. Has anyone else received this what appears to be a legitimate alert from PayPal? I get those regularly, and I don't even have a Pay-Pal account. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] CORRECTION
From: John E. Coleman (ARS WA5BXO) [EMAIL PROTECTED] You are correct of course, about the non specific 807 to 833 relationship but this would be true also if in push pull transformer or link coupled driver, AF or RF. . . However, it is different in the modulator of some BC equipment where an 807 is a direct cathode follower to drive a specific 833, and there is no driver XFMR. And then there is that Gates model that uses a separate pushpull 6L6 amplifier feeding the grid of each 833A, each through its own output transformer.
Re: [AMRadio] CORRECTION
- Original Message - From: Donald Chester In the Gates BC1-T, there are two 833A's, driven by two 807's. So I suppose you could say that each 833A is driven by an 807. That's true for the modulator section. In the PA, the 807s are in parallel, as are the 833A tubes. The PA is single-ended. But still, if two 833A's an parallel are driven by two 807's in parallel, you could say that each 833A is drivien by an 807. There are simply two 807-833A amplifier sections in parallel. This is not to say that a specific one of the 807's drives a specific one of the 833A's. Don
RE: [AMRadio] looking for HRO tuning knob
What usually happens with the HRO dials is that the setscrew scores the shaft, and the burr keeps the knob from coming off. I have always managed to get them off, but sometimes with great difficulty. I just recall pulling forward on the knob and finally working it loose. Sometimes it will rotate on the shaft, but not come forward. Avoid rotating the knob on the loose shaft; that will score a ring around the shaft and make it even more difficult to come off. I have never had to actually destroy a dial to get it off the shaft. I just tapped on the front of the knob, then pulled on it, and eventually got them to slide off. Early models had only one setscrew. Later models had two, located 90 degrees from each other. Don k4kyv
RE: [AMRadio] looking for HRO tuning knob
If it's an early HRO with the German silver dial (not painted black), do not destroy the dial. Replacements are almost impossible to find. Also, never use emery cloth,sandpaper or other abrasive to clean those dials. I always preferred a cloth lightly oiled with WD-40, and lots of polishing using a soft cloth. Eventually the oxide will go away and some shine can be restored. Abrasives will permanently ruin the surface. I once bought one of those receivers thru the Yellow Sheets. The receiver was in excellent condition, but the seller said that before shipping, the dial was a little corroded, so he polished it up for me. He had sanded it with a fine grade emery cloth, and the dial calibration markings were partially and permanently eroded away. Reminds me of the time when I was about 7 years ago, and I got into my uncle's collection of Indian Head pennies. I used sandpaper to shine some of them up to a bright copper finish. No need to even mention his reaction. National replaced the dial with the black painted version after the first year or two of production because the German silver tends to tarnish to a dull finish.
Re: [AMRadio] do not ground tower
I prefer the base insulator and series feed myself. Shunt feed or unipole feed works great if the tower is close to a resonant length. It becomes more difficult if the tower is much shorter than natural resonance. Sometimes top loading will make shunt feeding easier, since it raises the resonant frequency of a short tower. Series feed, if you can find an insulator, gives you a lot more options in tuning up the tower. Of course, if you are stuck with a typical ham radio style jury rig where the bottom section was embedded several feet into the concrete base, you have no choice. Unless the tower is short enough to stand without guys, that is about the worst possible way to erect a tower. A tall guyed tower is subject to much additional stress when the base is rigidly set in concrete; it cannot sway or rotate in heavy winds, and that can cause failure of the tower structure. If it is mounted with a base plate and pier pin, or a ball-and-socket insulator as AM broadcast towers are constructed, the base of the tower can follow the movements of the tower instead of having the entire tower bend and twist under high winds. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Check this out All...
From: gwt [EMAIL PROTECTED] If you think that's high, how about this price: It's a catalin radio. For some reason those things bring in big bucks. I have an Emerson AU-190 that I picked up for $3-4 at a hamfest in the 60's. I'm thinking about fixing it up. It has missing knobs but the cabinet is not cracked, and I was able to get a service bulletin for it. If it still had original knobs I could get a mint for it. Emerson and Fada are very sought-after brands. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] How the reply button works
From: W1EOF [EMAIL PROTECTED] This seems to come up on every list I belong to. It's not so much a bug but a choice. It also is NOT turning a reply into a reply-to-all. When you click the reply button it can only go one of two ways. To the list (the source of the email to you), or to the poster of the message to the list. It can only go one way or the other. I would contends that it is in the most favorable position. I'd guess that most of the time when someone replies, they want to reply to the list and not to the individual that posted the message. I seem to recall that most lists, when you hit Reply, the message goes to the sender of the message only. When you hit Reply All it goes to the sender AND to the list, so the sender gets two duplicate messages. To avoid that, you have to delete the sender, so that it just goes to the list. If there are other addressees on the original message, the Reply all message goes to each of them as well. I have inadvertently sent what was intended to be a private response to the entire list more than once. It can be embarrassing. It could conceivably bring on legal liability as well. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] How the reply button works
From: Brian Sherrod [EMAIL PROTECTED] Everyone, please send your vote to list so we can all feel confident in the final decision. I vote for letting the reply button send to the originator of the message only. Set the reply all button to send to the list. Don k4kyv
RE: [AMRadio] Homebrewing
Would be around 35w DC input (250v @ 125mA on the final). What I'm wondering, will the BTCL 10-80 band switch handle that much power? I would say so. You are talking about only 20w or so of rf. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Tower Construction
From: david knepper [EMAIL PROTECTED] I am thinking about buying a stick of Rohn 55G in cement with about 3 or 4 feet sticking out of the ground. I wonder how many sections of 55G I could mount without guys. I do have a strong base plate for the 55G but cementing a section seems to be sturdier. If you are not going to use guys, you need to bury the base section. But if you do use guys, it would be sturdier to use the base plate, to allow the tower to sway and twist at the base during strong windstorms. That would relieve stress on the tower structure that would otherwise result from a base section rigidly mounted in concrete. That's why most large guyed towers use a base plate and pier pin. Don k4kyv
RE: [AMRadio] ground sticks again
Grounding capacitors can be unfriendly, but lifesaving in the longer term. Not only unfriendly, but it can ruin the capacitors with excessive instantaneous current surges. Better to first discharge through a resistance to limit the discharging current, then apply the coup de grace by shorting directly. Large oil-filled transmitting capacitors are expensive and hard to find. Like tubes, we need to take extra precautions to preserve them as long as possible. I suspect that with the advent of solid state equipment and lower operating voltages, that HV capacitors in a few years will be as hard to find as most transmitting triodes are today. Don k4kyv
[AMRadio] AM songs (audio clips)
Check out the two AM songs that are presently up on the AM Forum. One it titled Come All Ye AM'ers, and the other, Fee Cee's Law Click on the URL (or copy and paste): http://amfone.net/Amforum/index.php?topic=7733.msg56781#msg56781 Now scroll down to the 4th and 8th postings, and click on the links. I saved both songs to my hard drive. Don K4KYV ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] CORRECTION
In the Gates BC1-T, there are two 833A's, driven by two 807's. So I suppose you could say that each 833A is driven by an 807. Don k4kyv
RE: [AMRadio] ground sticks again
From: Jim candela [EMAIL PROTECTED] Humans are expendable, but don't destroy them hard to find capacitors! :-) It's no less safe to discharge them gently, first using a resistor then discharging directly, than discharging them with a bang. Besides, if you discharge them with a bang a tiny piece of molten metal could hit you in the eye. I don't normally wear safety goggles while working inside a transmitter. That itself could be a hazardous distraction. Don k4kyv
Re: [AMRadio] ground sticks again
Reply-To: Discussion of AM Radio amradio@mailman.qth.net How do you intend to handle the resistor while doing the discharging? You are still going to need a shorting stick. It is much better to take the slight chance of discharging the cap the direct way than messing around with some Rube Goldberg resistor arrangement. If the Great Electron Gods had intended for capacitors to be discharged through a resistor (other than a bleeder) before working on a circuit, them he would have made discharge sticks with built in resistors. I have never seen one, have you? It is very easy to build one. Use something like a 500-1000 ohm 20-50 watt wirewound resistor. Rigidly attach it to an insulated rod, on the same end that you use to touch the HV. Better still, use a large enough resistor and small enough rod that you can pass the rod through the resistor, and clamp it down. Make sure everything is rigid enough that the resistor isn't dangling. To be safe, short out the capacitor directly after first using the resistor, just in case Murphy strikes and the discharging resistor opened up just as you discharged. This can most easily be done with a second, more normal shorting stick. I suppose one could get fancy and build a special shorting stick with a resistor and a direct shorting tip, in a mechanical arrangement that would resemble a Wouff-Hong, but to me it's easier to just have the shorting resistor on hand along with the regular stick. I don't use a resistor normally, after observing the expected drop-down of the plate voltage when the transmitter is shut off. Since the likelyhood that the capacitor is still charged is already remote, I am willing take the risk of blowing the capacitor or shrapnel in my face. But I NEVER KNOWINGLY DIRECTLY SHORT A FULLY CHARGED HV CAPACITOR. There's a lot of energy in that discharge, which can in itself can be dangerous, as well as ruin the capacitor. The resistor will feel warm to the touch after the discharge, even though it may be of very short duration. I once destroyed a 25 mfd 4000 volt capacitor by shorting it with a screwdriver. I opened the case and discovered that the flexible wire lead going from the guts of the capacitor, no larger than maybe #16, made from tinned, bare, twisted copper wire, had opened just like a fuse. I resoldered the wire and attempted to put the capacitor back together, but it still didn't work. The wire was probably vaporised at the other end too, and I didn't care to dig into the PCB saturated guts of the cap, so I just took the whole thing to the county's next household hazardous waste disposal day, and was relieved when they took it without asking me what it was. Transmitting caps are not that hard to find, not that expensive. You can find them at nearly every hamfest. At the Manassas, VA hamfest yesterday, there were 2 large piles of them at one vendor in the flea market and he would almost pay you to take them home. People said the same thing about VT4-C/211's, 2A3's, 6B4G's, 845's, and UTC LS-series audio transformers just a few short years ago. Don k4kyv
Re: [AMRadio] Shorting stick
If the stick is solidly grounded (I don't mean an alligator clip lead attached to a chassis point), why couldn't the shorting stick be a solid conductor, for example, a brass or copper rod? But I still would feel more comfortable holding something insulated, such as a phonolic stick. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Previous Text
I usually snip the original text, leaving just the relevant sentences or prhases, for clairity of what I am responding to. I'd rather spend the time to carefully compose and proofread my response, than to rephrase what has already been written. I have found that composing takes a lot of time. I can write a couple of paragraphs of message, in what seems like maybe 10 minutes, and then look at the clock and see that actually 30-45 minutes has gone by. Maybe that's just me, though. What I find objectionable is when someone copies the entire message verbatum, often including all headers, over their reply. That is wastful of inbox space, and makes the messages tedious to read. I know it's easy to forget and hit the reply button before deleting or editing the original text, since most e-mail programs are set up to send back the original text by default. As I recall, that default setting can be changed on most progs. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: RE: [AMRadio] Shorting stick
From: [EMAIL PROTECTED] ...somewhar in the shallow recess of my mind I recall one was to wire jumpers accross the oil filed caps (meter terminals also) and this (rebound) is probably the reason why...klc That's the reason for the wire across the oil caps. The wire across the meter terminals is to provide some magnetic damping of the movement - kind of like when you short out a generator it becomes harder to turn. The shorted terminals makes the movement bounce around less during shipping and handling, and less likely to be damaged. Don k4kyv
Re: [AMRadio] Shorting stick
Mike Dorworth, K4XM [EMAIL PROTECTED] On a BC-610 using a external VFO, just kill exicitation, ALL METERS fall to ZERO, the B plus will go to 4000 VOLTS and if you have bypassed the interlock and touch the link you will be GONE, Forget the meters! Trust the stick! I know! As I recall the 610 doesn't have a plate voltage meter. Every rig should have one. Even though it can fail, it offers one more stage of redundancy of protection. When I shut off my plate supply and see the plate volt meter slowly drop back to zero, I can be 99+% sure there is no high voltage. On my rig, all the grid and plate current meters drop to zero key-up on CW as well. That's one reason why all my HV supplies shut down on standby. I don't like the idea of HV silently lurking in the rig when it's not in use. If I ever did slip up, I think I would have a better chance of survival discharging a capacitor through my body, than serving as a load resistor on an active power supply. Besides, keeping the HV on all the time often generates noise and hash in the receiver. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] previous text -- do not include
From: W5OMR/Geoff [EMAIL PROTECTED] Do all yall up there in yankee land know what tumped means? True Southerners do. That's a new one on me. But then I didn't know what grits were, and had never tasted them until I joined the army. One of my favourite expressions: It would stink a buzzard off a gutwagon. Or somebody Makes my ass want to chew tobacco. (or work buttonholes) Here's more: http://members.aol.com/GLKS/colloq.html Don k4kyv
RE: [AMRadio] Shorting stick
From: [EMAIL PROTECTED] I always thought you had to discharge though a high value resistance to avoid damaging arcs that would hurt the surface you were discharging through a plasma arc. I do remember using a shorting stick in a job I had 20 years ago. I don't know about a high resistance, but I would be careful shorting out HV oil caps directly. If a high value capacitor, 25 mfd or more is fully charged near its maximum voltage rating, sometimes a direct short can blow the terminal connection open inside the case and ruin the capacitor. I would suggest a power resistor of several hundred ohms rigidly mounted on the business end. First, discharge through the resistor, then directly (just in case that resistor happened to open, per Murphy's law). Also, I have noticed that HV oil caps will sometimes rebound after a complete dischage and unexpectedly deliver a nasty shock sometime later. Don k4kyv
Re: [AMRadio] Stock or modify? BC rig value
From: [EMAIL PROTECTED] The plate transformer in a typical 1 kW tubed transmitter can deliver sufficient voltage and current to run an electric chair. YOU COULD GET KILLED! It isn't the voltage that kills, it's the current. You could get fried on a 12V battery if it gets you in the right place. But interlocks were put there for a purpose and defeating them is dumb, risky, foolish, idiotic and down right dangerous. For that matter, you can get fried wiorking on a receiver, too! Switch to safety! Very true, and I would never rewire around the interlock. On my BC1-T, I do sometimes use a thin washer to temporarily defeat the interlock, since otherwise, with the front grille removed, the power is shut off to everything. Even with the HV turned off, the exciter stage is killed as well. That makes it difficult to take voltage measurements, or tweak up circuits as needed. Of course, with the side or rear panels removed, the interior of the transmitter, HV and all, is accessible regardless of the interlock. Working on these things carries the same hazards as a comparable homebrew transmitter, and requires that you be alert and know exactly what you are doing at all times. Interlocks, designed to add a layer of proctection against carelessness, do sometimes fail since switches have been known to mechanically stick and contacts to weld closed, so don't trust your life to a properly functioning interlock circuit - there is just too much stuff there that can malfunction. Probably the safest interlocks are those that mechanically short out the HV using a spring loaded switch activated when opening the door or removing the panel, but even those are not 100.00% reliable. On my homebrew KW, I built in an interlock on the door that is opened for access to the plug-in coils, since these run with full modulated HV on them when the transmitter is operating. I would never try to change coils with the rig in TX position. The more redundancy the better. When I change coils, the interlock is turned off, the rig is in standby position, the main HV toggle switch is in the off position, and I have made it a habit to observe the plate voltage meter to make sure it is at zero. A shorting stick would'nt be a bad idea, either. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] stock or mod
From: W5OMR/Geoff [EMAIL PROTECTED] Rather than trying to re-design or rebuild the 75A-4 into something it was never meant to be, I prefer the other alternative: get another cool radio! Of course, I paid a fraction of the going epay-high price for mine or I wouldn't even be able to comment from experience. Seems like a lot of folks have paid big bucks for them because someone said they should. That's my thoughts. I think the 75A-4's price is artifically inflated. They weren't/aren't -that- good of a reciever. I have two 75A4's. Bought them in the early 80's. Paid $200 for one and $100 for the other. In stock condition, the receiver has excellent stability, sensitivity, selectibility and dial calibration. But the audio output seems an afterthought, and in the AM position the sound coming out of the speaker or headphones leaves a lot to be desired. However, the 'A4 can be converted to as good an AM receiver as its mechanical filters will allow, with a few REVERSIBLE mods. Change the coupling caps between the diode detector and firal AF stage to increase bass response (just solder caps with 10X stock capacitance right across the original ones without removing them, unless they appear to be leaky). Clip out the 510 pf AF by-pass capacitors Collins added to later serial # models to stifle the higher frequency audio response. I replaced the audio chain with an outboard 50's vintage 10-watt hi-fi amp, using plug-in adaptors to replace the 12AT7 (or is it a U7?) and 6AQ5, with NO wiring changes underneath the chassis. I also added 4 additional mechanical filter options using an outboard mechanical filter box. This requires a plug-in adaptor to replace one of the mechanical filters in the receiver, plus a couple of easily reversible wiring changes underneath: removal of the 100pf resonating caps (the filters in the adaptor box each has its own adjustable trimmer caps), and I MAY have had to slightly rewire the agc line around that filter position, but don't have the schematic in front of me. BTW, I did not completely remove the resonating caps, just clipped one lead on the hot side, and pushed the caps out of the way where they won't short to anything; they could be restored to the circuit simply by pushing each cap back into position and resoldering that clipped lead. The key to modifying vintage equipment is to make no mods that can't be reversed, and to keep good documentation so that you, or a subsequent owner, may rewire the equipment back to stock if desired. Also, keep on hand any of the original components that were removed. On my 'A4, I run all outboard leads through the ventilation louvres. No need to drill any holes in the front or back panels of the receiver. At hamfests, I have seen otherwise mint mid-30's National HRO's mutilated with extra holes drilled right in the front panel! Electric Radio sells (or at least used to sell) a compendium of mods and upgrades for the 75A4. Many of the mods are from CQ, QST and 73 magazine and some of these seem questionable to me, but the book also includes all known Collins-issued upgrades, many of which actually improve performance, such as hum reduction. An ESSENTIAL modificiation takes the B+ off the mechanical filters, since the stock circuit could result in destruction of every one of the filters if the plate of the i.f. tube, or some associated component, were to short to ground. The mods I have put in my 75A4 were added incrementally over the 20+ years I have used the receiver, but I could put it back into stock condx in less than a day. Don k4kyv
Re: [AMRadio] previous text -- do not include
From: Harry Vaught, KT4AE [EMAIL PROTECTED] Youse guys? Some sort of colloquialism I suppose, instead of the proper y'all or acceptable alternate, you'uns. Maybe a better term would be you-unses. Actually, this reflects a deficiency in the English languages. Centuries ago, we had a perfectly good set of singular and plural pronouns for you. You was the plural form, and thee and thou were the singular forms. For some reason, thee and thou dropped out of useage, and you came to be both the proper singular and plural form, and we have struggled ever since with makeshift plural forms such as you all, you guys, you-uns, youse, etc. Today,r thee and thou are mostly limited to Shakespeare and churchtalk. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Stock or modify? BC rig value
From: VJB [EMAIL PROTECTED] Modifications performed in keeping with spirit of the original quality of design seem warranted to the prospective ham as a way to continue to obtain the most useful service out of the transmitter, to provide greatest enjoyment to those of us on the other end receiving a classic signal like that, and perhaps best of all, settling the question of what to do with a 1000 lb beast if it is to be saved from the landfill or the scrap metal yard. THAT's why converting a BC rig to 160-75-40 is a valuable upgrade, in my opinion. Plus, just like a homebrew transmitter, a skillfully and carefully done modification or conversion places some ownership of the design to the user of the rig, making it more than just a polished-up used appliance. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] RCA blower
From: Rick Brashear [EMAIL PROTECTED] Thanks for the tips, Paul. There is no doubt the service will be considerably lighter than its original application and likely I could get by with less air flow. I'd just like to get it back close to original if possible. I will be looking for a quieter blower, no doubt. However, I've been searching for that elusive quiet blower for some time for my 3K Premier and have yet to find it. I cut down the blower noise on my Gates BC1-T to useable level by rewiring the fans to run at half voltage. Originally they were on a 220v circuit, so I rerouted the leads to run them on 110v. Despite reduced air flow, they still keep the interior of the transmitter cabinet cool, but instead of sounding like a vacuum cleaner running, I can just barely hear them. The transmitter is located about 15 ft from the operating position. Before the modification, I had to disconnect the fans altogether because the transmitter was too noisy to use in the same room. I checked, and the fan motors do not run hot at reduced voltage, which can be a problem with some electric motors. There was an unused toggle switch on my transmitter, so I wired it to operate the fans. With a flip of the switch, I can turn the fans on (at 1/2 voltage) or turn them off altogether. I usually do not run them in winter, when I keep my shack at about 60 degrees F to save on heating fuel. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Oscillator Filament Voltage change and frequency drift
...I later experienced band switch contact issues with that VF-1, and it was more like a spread spectrum exciter. Off to the dump that POS went. Recently, I have seen VF-1's go for big bux amongst the collectors. I wouldn't throw one away nowadays. One problem I discovered with my VF-1 was thermal drift. I took it apart and noticed the construction; the slug tuned coils are mounted on one wall of the oscillator subchassis, and the slugs and their bushings are mounted on the opposite wall. So as the temperature varies, the whole compartment expands and contracts, and moves the slugs in and out of the coils. No wonder the things drift! Then I noticed the insides of a DX-100, which has a nearly identical VFO. The coils and slugs are mounted on the same piece of chassis panel. So I remounted the coils in mine to the same side of the subassembly. It was easy - just drill a couple of mounting holes on either side of the original coil slug bushings (with the slugs removed during the process). I had to slightly re-route some of the wiring, but it was easy to hook everything back up, and it worked FB once reassembled. It didn't stop the drift entirely, but reduced it by at least 90%. It was nice and stable on 160/80, but was still drifty on the 40m. range. I ran the VF-1 off a CVT. It too, drifted with slight changes in fil. voltage. I think both the VF-1 and Collins PTO's use a 6AU6 as oscillator tube. My silent Sola beats fooling around swapping tubes. I suspect even a good tube would eventually become drifty with age. Don k4kyv
Re: [AMRadio] Ferroresonant transformer revisited
oh, yeah, you betcha! I've seen a few Sola filament transformers at different hamfests. heavy duty comes to mind, as the best way to describe 'em. I have a very light duty one to run my 75A-4. Even a slight change in line voltage, 1v, will cause the PTO to drift frequency, due to the change in filament voltage (B+ is regulated). I found a Sola CVT rated at about 100 v-a at a hamfest. About the size of your fist and weighs maybe 3-4 lbs. It was a modern unit, designed to supply power to a PC. Unlike most of the older version, it is almost completely quiet; I have to really listen carefully to hear it. It does run hot, but that's normal for those transformers. My complaint has always been that they sound like a chainsaw running. With that little xfmr, the A4 is stable as a rock. I use a T-368 PTO as my main station vfo. I stabilised it by running the filaments off a regulated DC supply. Also use it to run mic preamp. Now have stable VFO and hum-free microphone preamp. I'm not sure why a small fraction of a percentage variation in filament voltage will cause such noticeable drift. Without the regulated filament voltage, neither the A4 nor the T-368 pto are stable enough to work 40m cw using a narrow filter. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Ferroresonant transformer revisited
From: Rick Brashear [EMAIL PROTECTED] A while back we had a lengthy discussion about ferroresonant transformers. I received a lot of excellent advice and help. I have finally been able to apply what I learned... This sounds similar to my experiences with a Sola constant voltage transformer. Is that what a ferroresonant transformer is? Don k4kyv
Re: [AMRadio] 2-240A
From: Rick Brashear [EMAIL PROTECTED] Man, THAT is a rectifier! Sure would look good in a set up with a couple of 250TH's. You would do better with a pair of 575A's or 872's. That high vacuum rectifier will handle a lot of voltage, but look at the voltage drop at 500 ma. The tube would be useful for something over 10 kv and fairly low current. The filament consumes a lot of power as well. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Smoothing Choke
Sorry but I am going to throw a wrench into this discussion. Those swinging choke power supplies, although useful, have been out of favor for years, especially when the loading is transient such as for a CW rig. Sure if the critical inductance versus minimum load current are correct, the output voltage will not soar under a light or no load. But what happens when the load is applied suddenly such as with CW? The answer is arguable of course, but I think the answer is a sudden significant and momentary dip in B+ which all depends on the L-C-L-C values chosen. This is called the dynamic regulation. When keying a transmitter on cw, or running a class-B modulator or SSB linear, the plate (kilo)voltmeter may show little variation, indicating good regulation. But if you set up an oscilloscope to display the instantaseous power supply voltage, you may be surprised how much the voltage kicks around with the transients. The voltage not only dips down after the load is applied; when the load is removed the voltage will kick back upwards, and the momentum may swing it well above the nominal output voltage. I have seen power supplies where the voltage dropped below 70% nominal volatge and back up to 140% nominal or higher - a 2 to 1 voltage variation while the sluggish mechanical movement in the analogue voltmeter just barely wiggled with keying or modulation. Monitoring the cw output from a transmitter using a modulation monitor scope may show a horrible keyed waveform. The solution that has worked for me is to use as much capacitance in the output side of the filter as possible, without kicking the overload relay when the power supply is first turned on. I prefer to kill the HV during receive. Don't like having the full HV turned on while the transmitter is in standby - a death trap plus rf noise generator, and it hastens breakdown of HV components. You can use step-start if you want to further increase the capacitance, but I prefer to avoid that complication. Of course, increasing the inductance of the choke will reduce the inrush current to the capacitor by slowing down its charging rate. I converted my Gates BC1-T to CW capability, and was able to get a reasonable looking waveform by increasing the capacitance in the one-section choke input filter from 8 mfd to 25 mfd. It is still not perfect, but is satisfactory. My homebrew transmitter uses about the same capacitance each in the rf final plate supply and modulator plate supply. I have found that with a 2-2.5 kv power supply with a load not exceeding 700-800 mills total, a 25 mfd 4 kv output capacitor is about the best compromise between dynamic regulation and inrush current. With AM, the best solution is to use a common power supply for the modulator and final. The rf final acts like a heavy bleeder resistor, and maintains good dynamic regulation for the class-B modulator plates. Poor dynamic regulation can result in poor sounding audio, even though every component in the modulator is of the highest quality and the circuit is of the best design. If you are having an inexplicable audio quality problem, take a look at your HV power supply output voltage on an oscilloscope, to see what the dynamic regulation looks like. Connect up a series string of resistors, so that the total resistance is several times the normal bleeder resistance, and connect the vertical plates of the scope across the bottom resistor. Make sure the wattage and voltage rating of the resistors is not exceeded. Another way would be to temporarily disconnect the bottom end of the normal bleeder resistor, and insert a resistor of approximately 5% of the bleeder resistance in series with the bottom side. Place the scope probes between the connection between this resistor and the bleeder, and ground, to read the voltage across this resistor. If the resistor is 5% of the total resistance, 5% of the total voltage will appear across it. Thus, with a 2kv power supply, 100 volts will appear across the resistor, which is much easier to measure with a scope than the full 2000. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] antenna tuners transmision lines and more
From: John E. Coleman (ARS WA5BXO) [EMAIL PROTECTED] I have seen toriods used in HF tube type equipment also but they still have tuning. I was speaking of rigs with no internal tuning for the final amps. Most modern solid state equipment is this way. This type of equipment that has no output tuning must have a specific non reactive load attached or it will not work as specified by the manufacture. This is where external tuning equipment is necessary because it is very difficult to get an antenna to be non reactive and represent a 50 ohm load. And should you achieve this then it would only be for a small range of frequencies. Where as, if you had a rig with adjustable output circuitry such as a Pi-Net with a loading and a plate tune knob then you would be able to match a much larger range of frequencies even though the VSWR on the coax line may be as high as 2:1. What it boils down to is that with classic tube type rigs, the rf tank circuit was built into the rig. With modern solid state rigs, the rf tank circuit comes as an external option that you have to pay extra for. I recall there was a Central Electronics rig that had a no-tune broadband output network with a tube type final. They sealed the whole thing in something like epoxy, and gave no technical data on how it worked. I recall reading an article in CQ or 73 Magazine about how someone unsuccessfully tried to disassemble one of the networks to find out how it worked, and ended up with probably the only (Central Electronics rig) with a tuneable pi-network tank circuit. Don k4kyv
RE: [AMRadio] antenna tuners transmision lines and more
From: Brian Carling [EMAIL PROTECTED] The power may not be wasted very much in the tuner, BUT REFLECTED power goes back into the RF final and is disippated in the famil amplifier device(s) - at least many people have written articles for decades describing that marticular myth or so-called FALSE STATEMENT. I am not so sure it is false though! That is a myth. The power that is not radiated by the antenna or burnt up as resistive loss in the wire, goes back to tank circuit of the transmitter, contributes to the circulating rf current in the tank circuit, and is re-reflected back to the antenna. It may take several oscillations back and forth before all the energy is dissipated, but it is eventually dissipated in the antenna as radiated power and in the wire as resistive loss, not in the final amplifier tubes. The standing waves can be thought of as circulating current on the feedline. If the open wire line is left open with nothing connected, or if it is shorted, no rf escapes the feedline to excite an antenna. It is nearly all reflected back to the transmitter, and then back to the opposite end, until it is all dissipated as heat due to resistive losses. The current on the feeders, as measured with an rf ammeter, might be very high, but there is no radiation resistance or radiation. The rf ammeter may read seveal amperes while the final amp is dipped at resonance to near zero place current. There is very high circulating current in the tank circuit and the feeder, and at some points the voltage is very high - basically a Tesla coil, but negligible radiation. The myth I have often heard is that the rf is delivered back to the final and is dissipated in the plates of the output tubes. That is not true. If the plates of the tubes glow, it is due to plate dissipation (DC input to the final minus the power delivered to the tank circuit). This dissipation is due to operating conditions of the tube, not rf power being reflected back into the tube. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] 160 meters
I operate AM from about 1880 all the way to 1990. Most of my activity seems to be on about 1885 and 1985, but I often hear stations in between. I use a VFO with the Gates BC1-T, and the series fed quarter wave vertical works across the entire band. I wouldn't want to be stuck on just one tiny part of the band because so much of the AM activity is scattered across the entire band. I rarely transmit on AM below about 1880, but often operate CW on 1800-1825 or so. I find that for general QSO's, 1885 is mostly east coast to the Mississippi, and 1985 is mostly west of the Mississippi. I don't hear as much activity in the Gulf coast states as I used to. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] RCA BTA-1R1
Just put a RCA BTA-1R1 on 160 with the technical help of W4AEE, N4VMY and ER. Very straight forward and a fun project. I have a BTA-1R that I am probably going to part out since all the major iron is gone, unless someone want it. When are you goint to fire it up? Would like to hear it on the air. Did my audio xfmr workt ok? 73, Don
RE: [AMRadio] antenna tuners
From: Gary Schafer [EMAIL PROTECTED] Let's say you changed the output impedance of your transmitter from 50 ohms to say 200 ohms. (changing nothing on the tuner) Would the antenna system (antenna, feed line and tuner) still be resonant as you had them tuned when you had the transmitter set for 50 ohms output? The antenna system might still be in resonance, depending on what the reflected power on the open wire line sees when reflected back to the transmitter output. The transmitter puts a load, with a specific impedance, on the transmit end of the feedline just as the antenna puts a load on the antenna end. It's possible that the impedance that the transmitter presents to the feedline could have a combination of reactance and resistance that would alter the resonant frequency of the system. Another possibility is that it would stay in resonance, with no reactive component, but due to the load mismatch, there would be a reduction in coupling so that the transmitter would not load up to full power. A comparable example would be, if the above system used a balanced tuner with swinging link: You could tune the tuner to resonance, and then vary the link to achieve just the right amount of coupling to load the final to the desired load. Moving the link in or out would vary the load on the final, and thus final amp plate courrent, but if everything is tuned up to cancel out the reactance, after you vary the coupling with the link, you would re-check the dip at the final amplifier, and it would still be dipped at resonance, ever though the final might be loaded more lightly or heavily. I can do the same thing with my link coupled tranmitters. Adjust the tuner to resonance, which usually gives maximum coupling to the final. Dip the final. Now re-tune the antenna tuner. Adjusting the antenna tunerl should give a peak plate current, while adjusting the final amp plate tank cap gives a dip to the plate current. If everything is tuned to resonance, tune the ant tuner to peak plate current. Now re-check dip. It should still be dipped to resonance. Now adjust the link coupling. The plate current will increase or decrease, depending on whether the link is moved in or out of the coil. But once the coupling is changed, the PA plate current should still be very close to the minimum point (dip). If it is not at resonance, changing the loading with the link will require retuning the PA plate tank cap to resonance to maintain the PA plate current dip. If that is the case, no problem. Re-dipping the final brings the system back into resonance. With my link coupled transmitters, I usually have to touch up the dip after I change coupling with the link. The point is, adjusting any one or combination of the following: the PA tank settings, the antenna tuner settings, the antenna turner coupling coil (if link coupling is used), the length of the open wire feeder, the length of the antenna, will affect the resonant frequency and thus the reactance vs resistance of the network that couples the amplifying device at the final amplifier to the aether. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] antenna tuners
From: Gary Schafer [EMAIL PROTECTED] Another factor causing loss with a high SWR is dielectric losses at the recurring high rf voltage points along the line. At low impedances, it is the resistive loss in the wire, and at high impedances, it is dielectric losses that combine to cause signal loss. But SWR is much, much less critical than most hams have been led to believe. It is my understanding that at HF only resistive loss comes into play. Dielectric loss isn't a problem until you get into vhf. I would say it depends on what kind of balanced line you use. If it is well insulated, real open wire line, with ceramic or low-loss plastic spreaders, there is probably negligible dielectric loss at hf or even lower vhf. But if it is solid dielectric feedline, or even that pseudo-open wire line stuff that is basically heavy duty TV lead-in with square holes punched in the dielectric, I suspect there would be dielectric losses even at hf, and that they would increase with substantial SWR. The same goes for solid dielectric or foam type coax. However, for moderate SWR's, the loss is much less serious than most hams have been led to believe. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] DAYTON FLEA MARKET
I always drive out there, but can easily make it in one day and driving obviously allows bigger boatanchors to follow me home! What could be more frustrating than standing in the middle of the fleamarket, and right in front of you is the 1 cubic foot solid gold modulation transformer you have been looking for for decades, with a $25 price tag, and all you have is a handful of $20's and a plane ticket in your pocket? Don k4kyv
Re: [AMRadio] DAYTON FLEA MARKET
He anticipates the first large batch of vendor packets will ship this Saturday, 4/22, and will continue on until all vendor requests and packets are completed. And if you really believe that, I have a bridge I will sell you on Thursday afternoon.real cheap, complete with non operational cable cars. In kit form, no less.
RE: [AMRadio] antenna tuners
SWR is not all that bad either as long as the transmitter sees a match, especially the solid state rigs...And no, high swr on a feed line will not cause it to radiate. What causes feed line radiation is an unbalance between the two wires in the feed line. High SWR on coax line will cause a little more loss in the feed line due to the higher currents involved across the lower impedance of the coax. That is why when using open wire line that is 400 to 600 ohms, there is much less loss. The same power across a higher impedance means less current and less current going through the feed line wire means less power loss. Another factor causing loss with a high SWR is dielectric losses at the recurring high rf voltage points along the line. At low impedances, it is the resistive loss in the wire, and at high impedances, it is dielectric losses that combine to cause signal loss. But SWR is much, much less critical than most hams have been led to believe. An antenna tuner just matches the impedance seen at the transmitter end of the feed line to the 50 ohm transmitter output. If there is high swr on the feed line, any power reflected from the antenna is not wasted it is just re-reflected back to the antenna and eventually gets radiated. At HF even fairly high swr on coax lines does not cause excessive loss. My 160m. vertical uses a 140' run of buried RG-213 from the shack to the antenna tuner at the base of the tower. I set the L-network to match the tower 1:1 SWR at 1900 kc and locked it down. The SWR is about 2.5:1 at 1800 kc and the same at 2000 kc. I have measured the rf power input to the tower using a General Radio antenna impedance bridge and thermocouple rf ammeter, and at the same DC input power to the final amplifier, I could not detect any significant difference in rf power at the antenna end of the feedline, across the entire band. Of course at each point I had to re-measure the base impedance of the tower, note the rf ammeter readings, and re-calculate per ohm's law, so I do not guarantee precision measurements, but the ballpark power was consistent across the band, with no evidence of excessive loss at the top and bottom edges Don k4kyv.
RE: [AMRadio] Baluns for Zepp Antenna
From: [EMAIL PROTECTED] Simple Coax Balun www.southgatearc.org/techtips/coax_balun.htm Toroid Balun www.rason.org/Projects/balun/balun.htm Romex and PVC under $3.00 Balun www.bloomington.in.us/~wh2t/balun.html All those baluns operate on the assumption that the balanced load is primarily resistive. If the load is highly reactive, as is often the case with open wire resonant feeders, the balun may not function properly, especially the toroidal types at high power. I still prefer an honest-to-god balanced tuner, with split stator capacitor and symmetrical balanced coil. Don k4kyv
RE: [AMRadio] DAYTON FLEA MARKET
Well, based on what I am seeing, I am very seriously thinking of changing my plans. I doubt that I'll make it this year due to the screwed-up date. Can't get away from work that Friday. But the last couple of times I went, I could have fit everything I bought into one supermarket shopping bag. One of the reasons I have always gone is the goodies. It's less and less cost-effective to go, every year. I can recall not too many years ago that I would leave the hamfest with the car dragging the ground, the trunk, back seat and even the passenger seat if I had no riders, packed with stuff. The stuff that I like to bring home is getting rarer and harder to find; I already have much of what I see at the flea market; my storage space is running low. Therefore I have become much more selective about what I bring back. But mostly I just don't see much there that interests me any more. Don k4kyv
[AMRadio] Are Canadians smarter than United States-ese?
Back when the AM power proceeding was before the FCC, Johnny Johnston and his henchmen declared that preserving historic AM power levels under the new rf output power standard would have made the rules overly complicated. Look how easily the Canadian government was able to do it. Does that mean that people who live north of the border are smarter than people who live to the south? 10.1 Amateur Radio Operator Certificate with Basic Qualification: The holder of an Amateur Radio Operator Certificate with Basic Qualification is limited to a maximum transmitting power of: (a) where expressed as direct-current input power, 250 W to the anode or collector circuit of the transmitter stage that supplies radio frequency energy to the antenna; or (b) where expressed as radio frequency output power measured across an impedance-matched load, (i) 560 W peak envelope power for transmitters that produce any type of single sideband emission, or (ii) 190 W carrier power for transmitters that produce any other type of emission. 10.2 Amateur Radio Operator Certificate with Basic and Advanced Qualifications: The holder of an Amateur Radio Operator Certificate with Basic and Advanced Qualifications is limited to a maximum transmitting power of: (a) where expressed as direct-current input power, 1,000 W to the anode or collector circuit of the transmitter stage that supplies radio frequency energy to the antenna; or (b) where expressed as radio frequency output power measured across an impedance-matched load, (i) 2,250 W peak envelope power for transmitters that produce any type of single sideband emission, or (ii) 750 W carrier power for transmitters that produce any other type of emission. To view or download Canadian amateur regulations: http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/vwapj/ric2e.pdf/$FILE/ric2e.pdf ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Are Canadians smarter than United States-ese?
Bring up the link and you will note that the Canadians already use bandwidth-based mode regulation. The standard is simply a maximum bandwith for any signal anywhere in the band. Unfortunately (or apparently so) the prescribed bandwidth would be overly restrictive to AM if strictly enforced. On the lower HF bands, the only mode definition is 6 kHz maximum, with no subbands. Period. But I have never heard of a Canadian AM'er being cited for a signal of excessive bandwidth from his otherwise properly operated transmitter. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] W1AW vs. K1MAN
From: I COLLECT TRAINS [EMAIL PROTECTED] Can someone get me more info on that missouri station. Frequency/Mode/Times Exact. I live in Northern NJ and have a BW allband folded dipole with a kenwood ts450 :) I'd like to listen in. still a no-code tech(kc8gpd) so all i can do is listen. Listen on Saturday evenings at 1860 kc.
Re: [AMRadio] Triode connecting 803's for a Modulator
From: Mike Dorworth, K4XM [EMAIL PROTECTED] I assume all three grids simply strapped together. Is that correct? In some circuits with triode-connected tetrodes, particularly the 807, the screen grids are driven directly with the audio, and a resistor is placed between the screen and control grids. No, he had the screen and control grid strapped and fed. The supressor was biased in the center tap of the driver transformer with the voltage indicated. I overlooked the suppressor voltage you had listed. With the relatively high positive voltage on the suppressor grid, and audio on the cotrol/screen grid, it looks to me like this would better be called a pentode connected as a tetrode, not as a triode. The suppressor grid, with the steady +DC acts more like a screen grid, and the control/screen grid act like a control grid. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Triode connecting 803's for a Modulator
From: Mike Dorworth, K4XM [EMAIL PROTECTED] On page 662 of the 15th Edition of RADIO HANDBOOK by Editor and Engineers. Paragraph 30-8 the use of 803 in triode connection is fully discussed. A schematic (figure 20) shows 2500 volts at 18000 ohm plate to plate being driven by a 8 watt speech amplifier through a Stancor A-4761 Class B driver transformer set for 2:1 Ratio. Eg-g =170 volts Driving power 7-8 watts Resting current = 50 mA. Power output = 510 watts Supressor volts = 280-340 volts A Chicago CMS-3 was used for the output transformer.. I assume all three grids simply strapped together. Is that correct? In some circuits with triode-connected tetrodes, particularly the 807, the screen grids are driven directly with the audio, and a resistor is placed between the screen and control grids. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] : BC 610
I have always used John's idea of putting the HV plate transformers on one side of the a.c. line and all the rest on the other side, with my homebrew HF-300 rig (in which everything runs off a 115-volt primary). That way, the voltage sag caused by the current pulled by the modulator ADDS to the primary line voltage at filament transformers and low-voltage plate supplies. My pilot lights actully get slightly brighter under modulation. This is addition to the initial voltage kick-up caused by the current pulled by the rf finals, as soon as the transmitter switches to the transmit mode. Of course, the HV still sags normally as the power supply is loaded. Although I have never tried it, another idea, which might help modulation linearity with an especially poorly regulated power line, would be to run separate modulator and rf final plate supplies, and put the rf final on one side of the line and the modulator on the other, giving the rf final filament and plate voltages a boost under modulation. When my station was in the upstairs bedroom in the house, the line voltage would vary as much as 5 volts when the transmitter kicked in full strap. Now that my station is in a separate shack outside the house, with heavy duty wiring running out to it, the variation is less than 2 volts. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] W3PHL
Glenn Laser wrote: Hi group I am Glenn W3WTE At the age of 12 I lived about 3 blocks from W3PHL in Springfield. Wow what a antenna and I never met the man. Just imagine what happened when he came on the air and my Ocean Hopper was turned on. Every once in a while I could hear the station he was in QSO with. He was not popular with the neighborhood and people always said you don't want in that hobby; just see what you will do. I did QSO with him about 4 or 5 years later when I lived in Pittsburgh using my Globe Scout. Always wanted to know what happened to him and I did received the 2 meter repeater once in a while when we lived near Annapolis. Thanks for the memories and in no way mean this, to be a negative comment. 73 Glenn I used to talk with him quite regularly on 75, usually about 3810 kc, when he was running DSB reduced carrier. It was somewhat distorted but readable with loads of punch with the envelope detector. This was back in the mid 60's. I recall then that SSB'ers were always there, unsuccessfully trying to give him a hard time. I met him in person several times at the Cincinnati hamfest (used to rival Dayton for the goodies and held in late September, nearly always excellent wx). Sometime about 1971 I was passing through the area, and he invited me to stay overnight at his house. He showed me his station, and we got up before the crack dawn so he could work his regular VK and ZL friends at the top end of 40, using a full size quad on top of the big tower. By then he had dismantled the big DSB station and was running SSB, but he still had the components lying around from the big rig, and as I recall, some photos. Haven't heard much from him since then (maybe communicated with him once or twice after the visit). Never hear him on the air anymore. He would certainly be up in years by now. From what I understand, his business interests were taking more and more of his time, so he became less active in ham radio. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] : BC 610 needing POWER 220VAC
From: Rick Brashear [EMAIL PROTECTED] Well, Brian, you are right, the 11 ohm dropping resistor is only in series with the plate transformer... Of course, you're also right as is Jim that this would throw the modulation bias off... As indicated earlier, it's easy enough to operate with lower power by simply adjusting the coupling. I say easier sometimes that rascal can be real touchy. It's best to run the BC-610 in the full power mode. HV protect is for tuning up without risking damage to the final tube or other components. Running the rig in HV protect will result in very poor voltage regulation on the final, due to the series dropping resistor in the HV xfmr primary. Running it with reduced loading will throw the load impedance to the modulation transformer way off, with the possibility of blowing the xfmr or arcing something over in the final. The only proper way to reduce power would be to operate the plate transformer from a variac or some other kind of autotransformer, to provide a well-regulated source of reduced a.c. line voltage. Then the modulator bias would have to be reduced, but that would require extensive modifications, due to the combined audio driver plate/modulator bias power supply arrangement. Best to just run the BC-610 according to the stock instructions in the manual, if you are not confident about doing extensive modifications to the rig. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] possible interference coming up
My philosophy has always been: co-operate but OPERATE! Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] 10 Meter AM Frequencies
From: [EMAIL PROTECTED] [EMAIL PROTECTED] I'm somewhat intrigued with converting a CB radio to 10 meters from the pure technical perspective, but the typical 4 watts AM power leaves a LOT to be desired. Am I missing something here? I have a Radio Shack HTX-10 that does 7 watts AM but is more respectable on FM and SSB at 25 watts. I have one of those too, but have probably used it a dozen times in the past 5 years or so. When on 10m I much prefer my Eico 720 with modified 730 modulator, with the rig excited by a 40m DDS VFO. Sounds much better and puts out a bigger signal. The 7 watts on AM wouldn't be bad when 10m is open. But the thing has terrible audio. I looked at the schematic and couldn't figure out how to modify the audio so it wouldn't be so tin-can sounding. Has anyone else figured out how to do this? Of course you could always run a leenyar to boost the power. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] CB vs GB
From: VJB [EMAIL PROTECTED] 11 meter Class D Citizens Band as it once was known has faded out in popularity, so it no longer provokes me to hear any attention paid to it rather than ham radio. But I tell ya, I recall torturing people sitting in shopping center parking lots, walking up to them after seeing their good buddy antenna, and saying in a faux excited voice Hey is that one of those HAM radios??? Of course they'd say no, it's a CB, and I would put on a crestfallen face, turn on heel, and walk away. That reminds me of a few years ago when someone rang the doorbell, and it turned out to be a CB'er inquiring about my 127' tall 160m base-insulated vertical tower. He told me he had been noticing that tower for a couple of years, and that there was no antenna on it. He was wondernig if I would give the tower to him if he agreed to take it down. I hesitated for a moment, and pretended to be thinking about it, then replied, No, I don't think I'll get rid of it just yet. Might decide to put an antenna up there someday. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] W1AW vs. K1MAN
From: Phil Galasso [EMAIL PROTECTED] There is an exception which permits one-way transmissions for the purpose of code practice and for the dissemination of information bulletins of interest to the amateur radio community. This is the loophole that W1AW has used for decades. Years ago, I remember routinely hearing other ham stations besides W1AW transmit ARRL bulletins. There was even an official ARRL appointment called OBS, Official Bulletin Station. I recall reading in pre-WW2 QST's that these appointments used to be called Official Broadcast Stations. I think ARRL got paranoid in later years regarding the prohibition against broadcasting and re-named them bulletin stations. Haven't heard any of these for years, so I assume that the league has dropped the appointments. Of course now, with the internet, there is no need for widespread bulletin transmissions on the ham bands. Prior to Hiram's death, the HQ station was W1MK. I knew personally one of the old time operators who ran the station and worked in the ARRL lab in the 30's. His callsign was W9WT, and when I knew him he lived in Scottsburg, IN, just north of Louisville. He later developed alzheimers disease and was sent to a nursing home. His wife said he didn't recognise her or even remember what ham radio was. Some local AM'ers and myself were given everything in his station we wanted to carry away. We crammed full a large U-haul trailer. We found some real treasures in that pile of stuff. Unfortunately, one of the most irreplaceable treasures was a photo album from the 1920's showing many early ham stations. Probably the originals of the station photos in QST at the time. The photos were very clear and showed a lot of minute detail, but there was no identifying information on any of them, except for a few visible callsigns. Roger, N4IBF wanted the album, and promised to take very good care of it. At the time he worked at a photo shop, and he was going to make copies of all the pictures, but he never quite got round to it. When he came down with a terminal illness, he never wanted visitors. A few years after he had gone SK, I helped his daughter sort through his stuff, but that album was nowhere to be found. Don't know if it got tossed out after his death, or if someone deliberately took it. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] k1man fined
From: Mike Sanders K0AZ [EMAIL PROTECTED] This thread is painful at best. In the late 50s the then sales manager for Walter Ashe Radio in St. Louis, MO ran A2 code practice on 10 meters. From letter recognition to maybe 10 WPM. This was done on a regular schedule and was one way broadcasting. It helped a lot of young hams including me get their first ticket. The ARRL information broadcasts including CW code practice have always been for the benefit of hams. There has never been a commercial or political component involved in any of their broadcasts that I know of. It is possible with the changing times these broadcasts are not as important as they once were with email bulletins and such. However still to this day not everyone has a computer and some still get information from these broadcasts. Another active broadcaster is WA0RCR near St. Louis. He transmits weekly bulletins on 1860 kHz, calling it the Gateway 160 m. Newsletter. He transmits for hours, beginning in early afternoon, until past midnight. His transmissions originate from RAIN, Newsline, ARRL and other sources, many of which are also broadcast over local repeaters. The content is always ham radio related, and there are never any solicitations for money. Vern has been making these broadcasts since about 1980, even before LORAN was taken off 160. I have heard very few complaints about his operation, which is always conducted in a professional manner, and I have never heard any stories obout the FCC getting on his case. I think attitude has a lot to do with it. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Free kilowatt BC transmitter - Long Island NY
One can easily rent a trailer it will fit in It was my understanding that the transmitter was moved on site and the building was built around it, so that the transmitter could not be removed from the bulding in one piece.. Renting the trailer would be the best idea if the BC station would let you tear out a wall in their building to remove the transmitter, and not charge you for the damage. I'm not sure if the BC1-F cabinet breaks down into two pieces, or if it is unibody construction. If it can be non-destructiviely disassembled, it can just as easily be re-assembled. But in the worst case, it would be better for a ham to part it out than for the BC station to hire a bunch of goons as a wrecking crew to do the same thing, and then take it all to the landfill. I'm sure that has already happened too many times. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Free kilowatt BC transmitter - Long Island NY
From: VJB [EMAIL PROTECTED] Please take a look at this link. I've talked with a few people, and kindly pass the link along to anyone who has the interest in saving it from the scrap heap. It would be a real shame. That is quite a transmitter, dating back to an era when transmitters were transmitters, built with no limits to cost, size or weight in mind. Gates ads claimed that it was designed with performance as the only consideration, and then the cost was calculated after the fact. It is double the size of the later Gates kw boxes: 6 1/2 feet tall and 6 feet wide, 33 deep, and weighing in at 2650 lbs. (The BC1-T weighs less than 900 lbs). The mod xfmr alone weighs close to 200 lbs, and the modulation reactor is 100 henries at 600+ mills, and the plate xfmr is quite a monster. Uses a pair of 845's to drive the modulator 833A's - with real E.F. Johnson 833A sockets, not those house manufactured things on a strip of bakelite. The rig actually has turns counters for the rotary inductors, and there are 13 meters on the front panel. There are 4 doors on the cabinet, 2 in front and 2 in back. Those doors undoubtedly add several hundred pounds to the weight. I'm not sure if the cabinet separates into two sections or not. If so I would strip it down completely and then disassemble the cabinet and haul it out piece at a time. Otherwise, strip it down, buy a few sheetmetal blades for your skillsaw, and cut the cabinet into small enough pieces to get out the door, and use the goodies to build up a nice homebrew rig. By carefully cutting up the cabinet, the metal panels could be preserved for building something a little more compact for ham use. I'm not sure, but the cabinet panels may be made of aluminium, not steel. If so, this would be a real treasure indeed. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: Fwd: [AMRadio] Replies to the AM reflector
From: Brian Sherrod [EMAIL PROTECTED] Some of you may have missed this message I sent last week. If you did, PLEASE read. I would like to request that if you reply to any for sale items listed on our reflector, please do so directly to the seller, not the list. There have been a couple of instances recently where some long lists of items were for sale where the potential buyer(s) replied to seller on the list, and copied the entire list of items for sale once again in that reply. In addition to for sale replies, when replying to any post, please try to remember to delete excessive content from the original message or multiple replies to that original message when it is not appropriate. I know there are many cases where quotes from the original post SHOULD be included to keep things in context. Just use your good judgment on this. Thanks for your observance of this small request. Just a reminder that clicking on the reply button will direct your posting back to this list. To reply directly to the sender, you have to copy the e-mail address and paste it into the To: box. More than once I have inadvertently posted messages to this list when I had meant to send them only to the original sender. Don k4kyv
RE: [AMRadio] use of scope to monitor output audio
From: [EMAIL PROTECTED] How does a high vswr affect the modulated envelope on an AM TX? I would expect a decrease of forward power to decrease the envelope and distort the signal somehow. Perhaps suppressing the audio? I can't see how it would affect the modulated envelope in any way, so long as the final is loaded to normal plate current, nothing in the rf chain between final amplifier and antenna is arcing over on positive modulation peaks, and rf in the shack is not getting into the speech amplifier chain. Don k4kyv
Re: [AMRadio] Voltage regulator
Some of my antenna relays have protective diodes and some don't. If a power supply were to be used only for switching relays, could the protective diode be placed at the output of the power supply, rather than at the relay? To me, the diode acts more as a protector of the switch or pilot relay contacts. If the DC power supply has a filter capacitor at the output, the capacitor will look like a short to the inductive kick from the relay coil. If there is a regulator circuit, the spike could wipe out some of the solid state devices there. ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Voltage regulator
If its just relays, you can just add say a 5 ohm resistor on the output. measure the voltage with the relays pulled in, load/no load voltage will vary a lot... Or, if its DC, reduce the filter cap a lot, you don't need filtering for relays, and the size of the cap has a big impact on the loaded voltage you get out. Or, add choke input, Or, half wave rectify the thing, gives half the voltage output (use a big cap), 8 and 18 volts may pull the relays in fine. The three term regulators are mostly good for 1.5 amps, there are adjustable ones and fixed ones, I don't think the fixed ones have any additional parts...input, output, ground? One problem with the pass transistor circuit is that if the transistor craps out, you can have full output voltage from the filter cap delivered to the output. It probably wouldn't hurt the relays for a short period, but it would toast many other circuits designed to run off 12 or 24 volts. To be really safe, it would be advisable to add a crowbar circuit that would short out the power supply and blow a fuse in case of excessive voltage output due to regulator failure. Don k4kyv
Re: [AMRadio] Use of an oscilloscope to monitor am audio
I don't find a waveform (amplitude vs. time) display difficult to interpret. Over modulation in the negative direction shows up clearly as pearls on the baseline and positive peak levels can be easily read by slowing down the trace. Flat-toping can be clearly seen at higher sweep speeds. Admittedly, a trapezoid display can provide additional information but I've never found it worth the trouble. I find the trapezoid useful for determining peak positive and negative modulation percentage, since it is a little easier to interpret that looking at the modulated waveform. But it tells nothing about the waveform of the modulating signal. A severely distorted flat-topped signal looks almost identical to a pure sinewave. The trapezoid is most useful for observing the modulation linearity of the final. I have one of my transmitters set up where I can instantly switch from one to the other. One problem with the trapezoid is if you use it a lot, it will burn a vertical line on the face of the scope tube, since it displays a bright vertical line whenever there is no modulation. On envelope pattern, I have a relay to kick in bias voltage to deflect the patter off the screen when not transmitting. Leaving the horizontal base line on all the time will burn a horizontal line into the face of the scope tube. Don K4KYV
RE: [AMRadio] Amplifier to use with my DX-60
From: Brett gazdzinski [EMAIL PROTECTED] I myself cant even think about operating without the mod monitor and pep reading watt meter, its like driving at night without headlights! Actually I find wattmeters pretty useless. I prefer a thermocouple rf ammeter to indicate maximum rf current while tuning up and to monitor for normal rf line current to the antenna. I also find meter type modulation monitors of limited use. But to me operating without a monitor scope is like driving with the headlights off. I use the envelope pattern most of the time. Don ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Modulator feedback
, The UTC may work so don't discount it. Those I and H model transformers were only about half the size as the D and E models. I can't think of the company that made them but they were substantially different then the earlier models. The potted versions are made by Chicago Transformer Co. They are indeed much smaller than the older end-bell model like what is used in the E model. I suppose they work OK, because I have not heard a lot of complaints about blowing them, but I am still amazed at how TINY those things are. Don K4KYV
RE: [AMRadio] Modulator feedback
How much capacitance did you use? It should be at least 20 mfd. A cheap electrolytic should do ok, since there is only a few volts across it. Put it between the midtap of the plate transformer and ground. The positive side should go to ground, and the negative side to the transformer. In all the BC-610E's I have ever seen, that capacitor eliminates 95% of the chatter. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
Re: [AMRadio] Amplifier to use with my DX-60
My main concern Don is that giving out a calculated carrier level for a set of tubes to a guy who does not have a scope and audio generator is not going to give the amateur band another clean signal. As I mentioned in a previous email, I have been unable to obtain the efficiencies you mention and would like to hear from someone who can measure everything with test equipment and tell me about it. I have never worked much with AM linears or low level modulation in my own station, but I have helped others set up their amplifiers. I do recall getting a SB-220 working with a FT-301, running a KW DC input and about 350 watts carrier out, with good modulation on the scope and little downward carrier shift in modulation. I also recall a Continental Electronics 250 watt broadcast transmitter used as a stand-by at a station where I once worked, which used a pair of 4-250's in the final, running a combination of screen and control grid modulation. It ran 250 watts output, with full 100% modulation, and the DC input was exactly 750 watts input. I recall back in the 60's, Walt WB4AOE running a pair of 833A's in class B linear service and getting 350 watts carrier output, until he acquired a modulation transformer to run plate modulation with another pair. I hear a lot of guys on the air with AM linears, and most of the time they claim to be running way too much carrier for the tubes they are using. I often hear stuff like 200 watts out with a pair of 811A's or 250 watts out with a pair of 813's in g-g. If so, they are cooking the tubes, or else the efficiency is running too high, and they are flat-topping all over the place. To me, that's the disadvantage of low level AM. You have to fiddle with it and get everything just exactly right: not too much grid drive, make sure you have heavy enough antenna loading, and keep the audio level at the right place. With plate modulation, the antenna loading and rf drive are not critical. Just tune everything to resonance, and make sure you are not overmodulating (and that the modulator is putting out clean audio), and as long as the tube is running reasonably close to recommended parameters, everything will be ok. Unfortunately, very few hams use scopes as modulation monitors anymore. They have become so unpopular that the major transceiver manufacturers no longer include monitor scopes in their equipment line, and haven't done so for years. I suppose the new breed of ham finds oscilloscope patterns too complicated to understand. No wonder there are so many trashy signals on the air. Don K4KYV ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] Amplifier to use with my DX-60
From: Alan Beck [EMAIL PROTECTED] I would like to use a cheap am with my DX-60. An SB-200-230 seems to be a Class B amp. There for it only conducts on the positive going cycle. I don't mean to sound silly, but someone told me I could run this in SSB Mode using AM input from my DX-60, I run 100 Watts carrier for 400 Watts peak, now that makes sense. What does not make sense is how do I get the other side of the wave form The Tank??? I guess the tank. The linear will work on AM as long as you don't exceed the peak power output rating. Exceeding the peak output rating will cause the signal to flat-top, distort and splatter. Another thing to watch for is the plate dissipation of the tubes. If I recall correctly, the SB-200 series uses a pair of 3-500Z tubes in the final. That means you have 1000 watts of plate dissipation available. Running AM linear @ 100% modulation will give carrier output efficiency of about 30%. So you could run maximum 1500 watts DC input to those tubes, with 500 watts carrier output, and 1000 watts dissipated by the tubes. With modulation, the tubes will actually cool down slightly, since the DC input will not vary, but the amplifier will deliver sideband power in addition to carrier power output. So some of the input power will be converted to rf in the sidebands instead of heat in the tube plates. But you also have to be careful with the power supply. AM runs at 100% duty cycle, so the power supply in the amplifier may not be rated to run 1500 watts continuous duty. After a few minutes, the power transformer may overheat. In that case you will have to run it at reduced power. But be careful that the plate efficiency does not exceed about 33%. If you run it at too high plate efficiency, it will not leave you enough headroom to accomodate the positive peaks, and flat-topping/distortion/splatter will result. Don't worry about the missing half of the rf cycle. It works with AM exactly the same way as it does with SSB. Since the amplifier is single ended and not pushpull, the missing half of the rf cycle is filled in by the flywheel effect of the rf tank circuit. In summary, with class-B linear AM operation, the final will run about 33% carrier efficiency. The peak efficiency on modulation peaks will be about double that, 67%. Two-thirds of the DC input to the final will be dissipated as heat in the plates of the tubes under carrier-only, no modulation conditions. That means the carrier output will be one half the plate dissipation of the tubes. The peak power output should be about 4 times the resting carrier output at 100% modulation, if flat-topping is to be avoided. Linear amplifier AM operation dates back to the very earliest days of radio. The earliest high power broadcast stations used it. It was used for years before anyone figured out how to run audio amplifiers in class-B. Before then, the only kind of high level plate modulation that was used employed class A audio amplifiers, usually the Heising circuit but sometimes series modulation was used. Both those systems ran at lower ovarall efficiency than linear rf amplification. Therefore, AM linears were used long before high level plate modulation for high powered AM transmitters. _ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
