Re: [AMRadio] AM IARU Region 2 Bandplan
Whether or not this is their goal, (which as you point out isn't clear), it is an important point. Ham equipment is manufactured for the international market. That means we are at risk of being 'lowest common denominatored' into things we really may not want domestically, like ROHS standards that sprang from the EU, or the Kyoto protocol, carbon taxes, etc., etc. Any additional bandwidth restrictions in any band plan, even if it does not pertain to us as she is saying, makes little sense in today's world of SDR rigs, new modes, and rapidly moving technology. The spectrum should be wide open for experimentation and innovation, not artificially micromanaged to death. Gary W3AM sbjohns...@aol.com wrote: > ...It may also be a effort to drive people to buy new equipment that meets > such specifications. For example, a country might say in their ham > rules that licensees will follow the IARU bandplan, and use only > equipment which meets IARU requirements. That would rule out a lot of > old SSB and AM gear, as their published specs do not meet the undefined > yet written IARU 2700 Hz requirement. And homebrew would be right out, > as the specs are not available on paper somewhere... > > Steve WD8DAS __ 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] 7160Kc - The Video
Very nice, Paul. Thanks for letting us condo-bound prisoners vicariously enjoy the new 40Meter era. g VJB wrote: > ...We were talking Friday night about the idea of making a compilation > video to show AM stations and how they sound. Here's an attempt... __ 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] Ranger driving SB220
It's a good place to start. Here's some more info: http://www.w3am.com/ranger.html You don't have to do anything other than the screen mod if you don't want to. This is just one option for you. g Patrick Thompson wrote: Thanks to all who replied. If I go the route of lowering screen voltage is it enough to lower just the screen on the 6146? And turn the mike gain down? I like the idea of hiding the control shaft behind the crystal cover plug! Pat wa4tuk __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] Ranger driving SB220
You can lower the power in a couple different ways. Lower the screen, run the PA on the low HV, attenuate the RF, etc. If you're driving an amp there's no advantage to running full power in the Ranger. In fact, you give up a lot of potential positive peak modulation capability, if that's important to you. I vote for lowering the screen and making it adjustable. Second would be running the PA on the lower HV rail. There are numerous articles on line for modifying the Ranger to do these things. g Patrick Thompson wrote: How did you go about getting the RF drive from the Ranger down to a level usable by the SB220? I'm thinking about something similar to get to the 200-250 watt carrier level (or 800 to 1000 pep AM). I'm guessing the amp won't need much more than 10-15 watts drive (40 to 60 watts pep AM) leaving a little headroom. I thought about a homemade pad but that's a lot of heat to throw away. Maybe a 3db pad and turn the drive down a little? I could lower the screen voltage but it would be nice to have the rig full power when barefoot. Can you get by with just lowering the drive and microphone gain? Pat wa4tuk __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] Knight C-577 Manual/Skiz
Anyone out there have a manual and/or schematic for the old Knight Kit C-577 speech compressor they wouldn't mind selling or copying for a fee? Thanks! g __ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html 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 To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] the 3600 - 3635 spectrum
They should have retained the 5wpm code requirement for Extras only. A bridge too far. Most regrettable. Now that the cat is out of the bag, how long before they drop to only two license classes? g John Lawson wrote: I have some "mixed emotions", indeed BUT:... __ 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] Ranger... good news, bad news
Here's where we get into individual preferences and prejudices. I guess I can see where some hams may feel that way about the Ranger, but my prejudice is for high quality audio over communications quality audio. And my opinion is suitable for framing or wrapping fish. Anyway, the Ranger can do a nice job with your SB200 if you're careful and don't try to run more than ~150 watts carrier. Good luck! g Jack Schmidling wrote: ...Interesting as I also was reading a site that claimed the (stock) Ranger has the best audio of any ham rig on the market... __ 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] Ranger... good news, bad news
Yes, the screen mod can be made on its own, as can most of the others. Although it will change the Z the modulator works into it will not have a dramatic effect on audio performance which, quite frankly, already isn't too hot with the stock audio stages and mod xfmr. (Hence the more involved audio mods.) I certainly would not lump a screen adjust mod into the same power reducing option basket as a T connection and a dummy load or reducing loading, both of which I would agree are bad (lazy) ideas. The compromise in adjusting the screen is a small one. Try it and see, if you don't like it it's simple enough to take it out. FWIW it worked great for me. If all you want is to reduce the RF to feed a linear then just do the screen mod, or something like it. Many ways to skin this cat. All depends how complex you want to make things. g Jack Schmidling wrote: Guess I missed that "detail". Question though... can that change be made on it's own? Secondly, I found this contrary statement on another site Most often mis-modification: Reducing output power when driving a linear amplifier through the use of a T connection and a dummy load and/or reducing loading or screen Voltage. This situation wastes one of this rig's better resources namely modulator headroom. When altering the R.F. final's impedance through reduced plate current, the modulation transformer no longer sees the designed load. The correct way to reduce output power is to use an external plate supply with a Variac on the primary or switch the low B+ Voltage to the final (removing the high B+) through the accessory jack. Either way the high B+ is left on the modulators. This gives an immediate improvement to the audio as the modulator requirements are now cut way down without forcing the modulator into an unknown load. With the accessory low power mod, the rig will put out abour 12-14 Watts carrier which is a good level for driving quitea few linear amplifiers. Every available effort to clean up audio distortion should be considered when runnung QRO AM! Whom do I believe? js __ 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] Ranger... good news, bad news
Read it again. The 6146 screen adjust lets you put the RF out anywhere you want from a low of ~8 watts to full tilt. g Jack Schmidling wrote: Gary Blau wrote: Here's just one example: http://www.w3am.com/ranger.html That one is just the opposite of what I want to do. It increases power output. js __ 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] Ranger... good news, bad news
Here's just one example: http://www.w3am.com/ranger.html g Brian Carling wrote: Larry and Jack, there is an article on how to do just that on the web somewhere. As the others have said, it is the best way to reduce your drive to the RF final. From: Peter Markavage <[EMAIL PROTECTED]> Why not just make the screen voltage adjustable by using either a variable pot or some solid-state circuitry with a variable pot __ 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] Phase rotator schematic?
Here's only one example: http://www.w3am.com/8poleapf.gif You can get by with just 2 poles. g Craig Roberts wrote: > > Does anyone have a schematic for a phase rotator (audio type)? > > Many high-fidelity thanks, > > Craig > W3CRR
Re: [AMRadio] WTB Broadcast Mic 'boom arm'
Here's one manufacturer: http://www.ocwhite.com/html/microphone_arms.html They make a 3 section long arm that we use in many places. Not all their models are shown on the web site. Here's just one dealer: http://www.bgsfl.com g John Lawson wrote: > > Looking to find (and buy) one of those spring-loaded arms that are seen > in radio studios keeping an EV off the desk. > >I have an EV (668) and I'd like to get it and it's stand off my desk. > >If you have one of those 'boom arms' that looks like an architectural > light arm, but beefier - and would like to make it 'go away' - please drop > me a line Privately Off-List and we'll go from there.
Re: [AMRadio] Price 20V
Hey Bob. How's the refurb project going? g Bob Maser wrote: > > Free to $2000
Re: [AMRadio] 20V-2
Glad you were able to reclaim the meter panel, at least. g Bob Maser wrote: > > Cancel my want for the meter panel. I repaired the one that was broken. > Still need some meters though. Can anyone give me direction how how > complicated putting this transmitter on 160? The book by Bill Carn was > great for modifying the 20V-3 for 75 but now I thinking that maybe I would > put the 20V-2 on 160.
Re: [AMRadio] Wanted: 20V-2 or -3
Bob: I'll have to take some pix, it's been in air conditioned storage now at the work QTH since it was removed from bdcst auxiliary service ~5-6 years ago. Was (still is) on 1580, and was last seen operating there at ~500W. Condition is well used, needs considerable attention and cleanup, but is quite serviceable. Some small spare parts. It's a project, not a plug-n-play. All offers and/or trade considered. Not looking to bone anybody, e-bay style. Would like it to go to a good (amateur) home where it will be used on the air. Pick up only! g Bob Maser wrote: > > Well, I already have a 20V-3 that's about ready for the smoke test. I am in > the Tampa area. Can you send me some pics and tell me what comes with it > and how much $$$ you are looking for? My friend will be visiting us here in > Tampa early this summer. He will be pulling an Airstream trailer. > > Bob W6TR > 813-643-3034
Re: [AMRadio] Wanted: 20V-2 or -3
Hey Bob: This probably isn't what you had in mind, but I have a 20V-2 here waiting for conversion that it looks like I'm not going to be able to get to any time soon. Trouble is it's in Miami, FL! Does this help? 73, g Bob Maser wrote: > > I am looking for a 20V-3 or -2 for a friend of mine who lives in the San > Francisco area. He would be willing to travel to collect his prize. > > Bob W6TR
Re: [AMRadio] AM Amps
Not sure I understand that answer. If the amp can easily handle 1500W PEP, and if your audio is symmetrical (a big if), then the dreaded 375W number is a safe place to start. (I can hear gaskets popping out there now...) If you have a PEP wattmeter, then adjust while looking at that for a max of 1500W on highest voice peaks. Make sure your negative modulation is <100%. More importantly, tune up the linear with full drive. Use a driver that can deliver 100W or whatever the amp needs for 1500W PEP out, and tune there. (You might use your SS ricebox with a CW keyer sending dits to keep the duty cycle low while tuning.) Then leave it alone. Connect the Ranger and adjust the screen for that unmentionable number just to start. The amp tubes will be dissipating a lot of power, so be sure the tubes can handle the dissipation at dead carrier (the worst case), as described by Gary Schafer several posts ago. Rock and roll. g Geoff wrote: > > Byron Lichtenwalner wrote: > > > If you had an amp rated at 1500 pep rated for Continuous Commercial > > Service and were going to drive it with a Ranger, (with W3AM's > > modification as an example) where would you set the carrier level with > > no modulation? > > Byron, W3WKR > > Where the 'scope showed that I had 90% negative modulation peaks. > > "Operating your AM rig without an Oscilloscope > is like driving your car at night, without headlights" > (Don Chester -K4KYV) > > 73 = Best Regards, > -Geoff/W5OMR >
Re: [AMRadio] AM Amps
Hey Geoff: Since there's already a screen at hand, why not use it to your advantage in this case by making it variable to allow clean adjustment of output power? It just seems like what the doctor ordered for driving a linear, that's all. As for your second question, I should have clarified that I was not thinking of a simple phase inversion aimed at impressing the highest voice peaks to the negative modulation direction, (the primary idea of the article) but taking it to an extreme of radically reducing the positive peaks by some means (such as very agressive positive peak clipping, or unplugging the positive tube in your push pull modulator!). Of course, simply inverting the phase in and of itself will not hurt quality in any way. But while aggressive positive limiting of some sort would allow higher carrier power before reaching the PEP limit of 1500watts, it will also increase distortion. How bad or tolerable it might be depends on a lot of variables and the limiting techniques employed. If you just want the most intense 'communications quality' result possible from the rig at hand, then it might make some sense. But in the real world, how much of a potential benefit is at stake here? Even wildly asymmetrical voices aren't going to buy more than several dB relative difference between positive and negative peak voltages, an amount that can easily be made up for with modest audio limiting. Since some sort of negative peak limiting should be used anyway to protect from carrier pinch off, some amount of that asymmetry is going to be given up right there. Finally, if your voice doesn't happen to be wildly asymmetrical, you're out of luck anyway. A lot of AM hams don't seem to use any negative peak control other than the mic gain pot, and many don't even have a scope to monitor for carrier pinch off, so a lot of this is like counting pixies on the head of a pin. FWIW my prejudice is looking at this as a broadcast engineer, which may be a bit different than some AM ops. Not better, just different. That prejudice steers me toward high audio quality, consistently very high average modulation levels (loudness) being almost always more useful than modest increases in carrier power, and a paranoid fear of negatively overmodulating. I admit to impatience with low power stations that do not agressively modulate to make up for it, which is common. Sorry. My object is to rattle the speaker on the other end, and make the station easy to listen to no matter what power level is in use. But, clearly hams can operate successfully without concerning themselves with any of this and still have a ripping good time. We're all looking for our own buzz. g Geoff wrote: > > >...I'll be the first one to admit that I'm 'weak' when it comes to > pentode/tetrode design/operation. I like triodes. Their easier > to work with, and require fewer power supplies. Less can go wrong. > > > ...Why wouldn't it sound as good? You've just reversed the 'phase' > of the audio if you, say, switch the grid caps on the modulators, > or switched the plate caps on the modulators, even reversing the > polarity of the microphone would have *basically* the same > effect. Yes, your positive peaks would reduce, and you can run > the carrier level back up. > > At 1500wPEP output (as John so eloquently described in his > article) with his rig and voice, he would have to keep his rig at > 220w input (around 160w of carrier out) to keep within the 1500w > limit. Inverting the audio phase, he could probably run 1000w of > carrier, with PEP audio to 1500w, still have the same QUALITY of > audio, -and- probably be heard better, due to the lack of > interference from the 160w carrier, to the 1000w carrier. > It just wouldn't sound -as loud-.
Re: [AMRadio] AM Amps
Not sure where the article is exactly pertinent to this. If the exciter B+ is reduced, so is the max available exciter PEP. If the B+ stays the same and the screen V is reduced the max available exciter PEP is (roughly) the same, but the carrier power out (no mod) goes down. If your concern is running as much carrier power as possible while staying within the (stupid) 1500W PEP limit then reduce your positive modulation as much as you can tolerate while keeping the negative modulation as consistently high as possible. Won't sound very good, but there it is. g Geoff wrote: > > ...I don't think that's what happens. > > http://w5omr.shacknet.nu/~wa5bxo/asyam/Amplitude%20Modulation.htm > > That's a great read. Everyone -should- read that.
Re: [AMRadio] AM Amps
Although both of these will serve to reduce the drive power and get you on the air, they are less than optimal. The problem with reducing the B+ is the max PEP goes with it. You'll want to preserve that for positive modulation peaks. As Gary Schafer sez you want to keep the driver PEP up to where the amp needs it for full output, as long as the plate dissipation is not exceeded during dead carrier. Better to keep the plate hi and pull back the screen V. A simple attenuator wastes heat, may be difficult to adjust over a wide range, and offers no improvement in modulation performance over the stock exciter running at full power, (limited positive peak capability). But, a better idea than lowering the B+. g Geoff wrote: > >...Reducing the B+ level on the plate of the 6146 is another way. >...A "T" connector, and a dummy load works well, also. > > Just tossing out some more ideas.
Re: [AMRadio] AM Amps
I partially disagree, but with a -big- proviso. You'll have to find a way to reduce the Ranger output to the 10-15 watt level. Maybe the nicest way to do that is a variable screen voltage control, similar to what you'll find here: http://www.w3am.com/ranger.html but I'm sure there are other methods. Just don't run the stock Ranger straight into the amp without dealing with this in some way. Don't ask the 30L1 to do more than ~125 watts carrier. The 811's can't handle much dissipation. Same is true for the SB200 and its pair of 572B's. But they both will work fine like this. I ran an SB200 like this for a long time. Bigger amps with more plate dissipation, like the Henry or SB-220 are a safer bet, but you must be very careful nonetheless. 73, g Chris wrote: > > Hi Dick > The 30L1 would far too over stressed but the Henry would be perfect, by > the way thanks for buying my Ranger, 73 Chris > > RICHARD W GILLESPIE wrote: > > > I just bought a Johnson Ranger and wonder if my 30L1 or Henry 2KD > > would work okay. 811's in the 30L1 and a pair of 3-500's in the Henry. > > Thanks. > > > > Dick/K5DIC
Re: [AMRadio] Frequency Response
Exactly. However, if you intend to employ significant audio clipping as a means of peak control and loudness enhancement, the low freq response should ideally extend well below that to better accommodate the flat topped waveforms without substantial elevation of their peak level caused by the tilt. But again, this is only ham radio and your rule of thumb is a great one. If everyone's rig passed that test we'd be talking about something else. g Donald Chester wrote: > > >By 'tilt' I mean the observable tilting of the top and bottom of a > >square wave (or resulting modulated envelope) caused by low frequency > >roll off and non constant group delay through the transmitter in > >question. > > That's why the transmitter frequency response, including transformers, > should be essentially flat at least one octave above and one octave below > the actual range of frequencies you plan to transmit. > > For example, if you intended to limit your audio response to 150-4000~, the > audio chain should test flat from 75 to 8000~. > > Don k4kyv
Re: [AMRadio] WTB SB-220
No argument there. g RJ Mattson wrote: > > If you can't get out consistantly with a Viking II, you need an antenna - > not an amp. > bob...w2ami
Re: [AMRadio] Frequency Response
By 'tilt' I mean the observable tilting of the top and bottom of a square wave (or resulting modulated envelope) caused by low frequency roll off and non constant group delay through the transmitter in question. Ideally what you want is waveform fidelity, what goes in should come out. The closer you can get to this ideal the better. Square wave tests are very useful as they will tell you a lot of info in one picture, and many hams have function generators available, (and if you operate AM you should already have a scope). This tilt will increase the peak voltage of the incoming waveform. This in turn will force you to reduce your average modulation level to keep the increased peak level from overmodulating the transmitter. The same result happens from any ringing or overshoot the system may have. Where this becomes a significant issue is if you try to drive this poor performing xmtr with waveforms that have flattop components, typically produced by audio clipping. You end up fighting yourself as you just increased your average level with the clipping, but are then forced to turn it down again to some extent by the inability of the xmtr to pass the waveshape. Since some degree of peak control is necessary to prevent negative overmodulation (and the resulting splatter and unneighborly excessive occupied bandwidth), this all conspires against you to produce a less than fully modulated signal. There are some low level audio gimmicks that can be applied to partially compensate for this, but it's always best to go after the root cause and improve that first. Granted this is only ham radio and it's not a big deal if everything isn't optimized. But it's interesting to look at all this and try to improve things, and it gives us something else to talk about on the air other than politics! I'm looking for some helpful pictures for you but haven't located any at hand. FWIW, you might look at Fig. 2-9 on page 2-22, and Fig. 2-10 on page 2-24 of the operating manual for the Orban AM Optimod 9100B, which is on their FTP site here: ftp://ftp.orban.com/9100B/9100B_Manual_Section_2.pdf That may help make it more clear. g Byron Lichtenwalner wrote: > > Gary > I have read several of your writings that refers to "tilt". What is it, or > where can I go to learn more about it? > Byron W3WKR
Re: [AMRadio] WTB SB-220
I've always found more RF power, at least in significant iterations of ~100watts, can make a big difference on the air in cutting thru noise and band conditions. But what's more important is full modulation. One potential benefit of running a -modified- Viking or Ranger, etc. into an amp like the SB220 is you can then concentrate on improving the modulation performance of the exciter xmtr. This can in turn deliver a more effectively modulated signal thru the entire system and thereby on the air. Add that to the increased power ability of running a fully modulated ~400 watts carrier, and a case can be made that this is one of the easiest ways to get a big AM signal on the air. The easiest is to use a rice box for an exciter, but that's another fist fight. The Viking would have to be modified a good bit to optimize this approach. The first problem being reducing the RF output to the 10-25 watt level that the SB220 will want to see. I've never had a VikingII, so I can't say for sure, but my first thought is to try a variable PA screen voltage scheme. (I did this to good effect in my Ranger.) You'd probably have to remove one of the 6146's in the Viking, and make other changes as well, but the idea is that not only will you be able to vary the drive to the amp, but it will also give the huge benefit of much higher positive peak modulation capability. Positive peaks can easily go way beyond 100% as the PA now is operating well below its peak dissipation point. Even if you're not a believer in hugely asymmetrical 'supermodulation', having an xmtr that can easily handle it will still be a big improvement over the 'stock' Viking. Loudness is where it's at to get thru on a noisy band, but having an extra 100-200watts as well makes a potent combo. g [EMAIL PROTECTED] wrote: > > << I am looking for a Heathkit SB-220 to run about 300 watts on AM using the > Viking II to drive it. >> > > Hi, > > If you are getting the full output from the V II into a good well matched > antenna, a couple of hundred more watts is not going to make any significant > difference on the receive end and will only serve to heat up the shack and > run up > your power bill. > > 73, > > John, W4AWM
Re: [AMRadio] Frequency Response
IMHO, the best approach is to terminate the mod xfmr (or any audio xfmr) for best transient (square ware) response of the modulated envelope, not just an arbitrary upper frequency. Adjust for best stability, least overshoot and ringing on leading edges, and the least tilt. Check it at mid freq's, say 1khz, as well as low (50hz) and high (5khz). It's easier to see the tilt on the low end, and the overshoot on the midrange. All of these disturbances rob modulation power from you, as you have to reduce average modulation level to keep the peaks from overmodulating. Cleaning it up will help maximize modulation control, sometimes as much as several db. This in turn increases potential average loudness which is the name of the game. The best place for audio bandwidth control/limitation is in the low level audio chain. As to where to roll it off, I'd suggest 5khz, but I like to make it variable depending on conditions. With only 3KHz you might as well be on SSB. g Edward B Richards wrote: > > Tom; > > I believe the standard for communications is 300 to 3000 CPS +/- 3 dB. > > On Fri, 24 Sep 2004 14:54:49 -0800 "Tom Elmore" <[EMAIL PROTECTED]> writes: > > I am in the process of restoring a Stancor 60-P transmitter to > > service. I > > have replaced all the capacitors in the power supply and in the > > audio > > amplifier sections. I would like to terminate the modulation > > transformer > > with the correct resistance and check for frequency response on my > > scope. > > What is a good ballpark response that I should use for operating AM > > in the > > amateur bands. > > > > Thank You > > Tom Elmore KA1NVZ > > Anchorage Alaska
Re: [AMRadio] [FWD]: HEAVY IRON FOR SALE
Tnx, John, but they're not mine. Please let Bobby know directly. 73, g John Coleman wrote: > > Hi Gary I will be glad to post these pix for you > > Email to [EMAIL PROTECTED] > > John, WA5BXO > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Gary Blau > Sent: Monday, September 20, 2004 6:07 PM > To: Discussion of AM Radio > Subject: [AMRadio] [FWD]: HEAVY IRON FOR SALE > > FWIW, I'm posting this note from the Broadcast.net radio-tech email > list. > I thought one of you gents might be interested in an old Collins AM > boatanchor. > Contact Bobby directly: > > > ATTENTION AM COLLECTORS & HAM OPERATORS > > I HAVE UNEARTHED THE FOLLOWING AND HAVE CLEARANCE TO SELL THIS ITEM: > > 1 COLLINS 21E-1 AM BROADCAST TRANSMITTER DRIVER BAY > SERIAL NUMBER 24 > BUILT ON 12-21-1954 > > MY UNDERSTANDING IS THAT THIS TRANSMITTER WAS A 250 WATT BACKUP > TRANSMITTER. IT THE DRIVER ONLY PORTION OF THE > FULL 5500 WATT AM TRANSMITTER. IT IS IN IMACULATE CONDITION, ALL > ORIGINAL AND I HAVE THE BOOK AND ORIGINAL TEST > DATA. > > IT IS IN GEORGIA. IT HAS BEEN ON THE AIR IN THE LAST 8 YEARS. I AM > MOVING MY AM SITE AND THE MUSEUM PIECES NEED TO GO > TO GOOD HOMES. IF THERE IS NO INTEREST ON THIS LIST I WILL PUT AN ADD IN > QST AND THEN IM GONNA PUT IT ON EBAY. I > WANTED TO KEEP IT IN THE FAMILY OUT OF THE GATE. I CAN E-MAIL PICTURES > OFF LIST OR CAN EMAIL TO SOMEONE TO POST ON > A TEMP SITE. TOO BUSY TO BUILD A SITE RIGHT NOW. I AM DICTATING THIS > EMAIL TO AN ASSISTANT. > > BOBBY GRAY > [EMAIL PROTECTED] > ARCHWAY BROADCASTING > COLUMBUS GEORGIA
[AMRadio] [FWD]: HEAVY IRON FOR SALE
FWIW, I'm posting this note from the Broadcast.net radio-tech email list. I thought one of you gents might be interested in an old Collins AM boatanchor. Contact Bobby directly: ATTENTION AM COLLECTORS & HAM OPERATORS I HAVE UNEARTHED THE FOLLOWING AND HAVE CLEARANCE TO SELL THIS ITEM: 1 COLLINS 21E-1 AM BROADCAST TRANSMITTER DRIVER BAY SERIAL NUMBER 24 BUILT ON 12-21-1954 MY UNDERSTANDING IS THAT THIS TRANSMITTER WAS A 250 WATT BACKUP TRANSMITTER. IT THE DRIVER ONLY PORTION OF THE FULL 5500 WATT AM TRANSMITTER. IT IS IN IMACULATE CONDITION, ALL ORIGINAL AND I HAVE THE BOOK AND ORIGINAL TEST DATA. IT IS IN GEORGIA. IT HAS BEEN ON THE AIR IN THE LAST 8 YEARS. I AM MOVING MY AM SITE AND THE MUSEUM PIECES NEED TO GO TO GOOD HOMES. IF THERE IS NO INTEREST ON THIS LIST I WILL PUT AN ADD IN QST AND THEN IM GONNA PUT IT ON EBAY. I WANTED TO KEEP IT IN THE FAMILY OUT OF THE GATE. I CAN E-MAIL PICTURES OFF LIST OR CAN EMAIL TO SOMEONE TO POST ON A TEMP SITE. TOO BUSY TO BUILD A SITE RIGHT NOW. I AM DICTATING THIS EMAIL TO AN ASSISTANT. BOBBY GRAY [EMAIL PROTECTED] ARCHWAY BROADCASTING COLUMBUS GEORGIA --- g
[AMRadio] Re: 1kw AM rig available
FWIW, I'm forwarding this to the list in case someone is interested. Contact NG1U directly at: [EMAIL PROTECTED] g Craig Healy wrote: > I have a mid to late 50's RCA BTA-1MX transmitter available for the taking. > It is complete, and I believe it was working when removed from service. > Includes a manual and a couple of extra 833A tubes. Currently on 1340 and > includes crystal and oven. > > Must be picked up in New Bedford, MA before the end of August, 2004 > > Please let me know if you or anyone else is interested. A current General > or above ham license is required. > > Craig Healy > NG1U > Providence, RI
Re: [AMRadio] Modulation Question
Howdy Ed. Edward B Richards wrote: > 1. It is hard to tell modulation percent with voice as the waveform keeps > changing and unless I use a sine wave I can't sync it to get a good > envelope pattern. Any trick to this? You're not going to get it to sync reliably to a complex waveform like speech. But it's not necessary in order to use it as a mod indicator anyway. As long as you can clearly see what the negative and positive peaks are doing, that's all that matters. Just adjust the sweep rate to a slow enough rate where low frequencies are easily seen. Calibrate your scope so that your dead carrier occupies 4 vertical divisions, (2 above and 2 below zero axis). Then 100% positive peaks will be where the envelope extends to 8 total vertical divisions, (4 above and 4 below the zero axis). 100% negative is where the carrier pinches off in the center, of course. > 2. Using the mod mon I see that it is very easy to over-modulate. If I > keep the modulation down so I don't see short bright lines in the center > of the screen (carrier disappearing, I think) , the average modulation is > around 50% except for occasional peaks. Is this normal? would a > compression amplifier help? Thank you. Very normal. To get the average up, at the very least you'll need to tightly control peaks and limit them to never negatively overmodulate the carrier. Positive peaks you can let go if you like. IMHO everyone needs at least a peak limiter of some sort. 73, g
Re: [AMRadio] Fw: NPRM -- Broadband over Power Line (BPL)
Yeah, we'll see how quick they are to happily 'notch out' the QRM they cause to a single Amateur complainant, even if he knows what the source is from this great registration database they're hawking. First, how is interference to be measured and quantified? Who will 'fact check' the interference data the utilities themselves will supposedly have to maintain, or judge each interference case? FCC field inspectors?? That's a laugh, the handful who are left can't handle their exploding workload now. And nobody's talking about adding FCC enforcement personnel, quite the opposite. (But you can sure count on more lawyers in the agency.) The burden of proof thus will be on the licensed complainant's side, not the unlicensed Part 15 operator's side. That one complainant could shut down or restrict service to a much larger number of citizens immediately makes the complainant the 'bad guy', and it won't be long until he gets steamrollered by 'the greater public interest'. It's a scenario that's a set up to lose. Political Science is where votes and money, not physics, make things happen. g Geoff/W5OMR wrote: > - Original Message - > Sent: Thursday, February 12, 2004 9:06 PM > Subject: NPRM -- Broadband over Power Line (BPL) > > > Gents and Ladies -- > > > > The FCC held a public meeting today (Thursday, Feb 12) where the subject of > > a Notice of Proposed Making (NPRM) relaxing limitations on Part 15 devices > > between 2 and 80 Mhz was discussed. We also know this is the Broadband over > > Power Lines (BPL) controversy. It appears the meeting was less than > > positive, SEE: > > > > http://www.arrl.org/news/stories/2004/02/12/5/?nc=1
Re: [AMRadio] A Reminder - ALL PLEASE READ
Hey, Brian: As someone who is likely one of your occasional 'perps' in this matter, first let me apologize in advance. Sometimes when hastily posting from work or home it's easy to forget what's what. But that's no excuse. I don't expect you, or any other list I belong to, to change your policy and be my nanny. It's far more important to keep the list tidy and useful to all, and the web lids at bay. And if you're spending time sifting thru bounced posts, I'd suggest just letting them fail. Eventually we'll figure it out when we don't see our posts pop up. No sense making yourself crazy over it. g "B. Morgan Sherrod" wrote: > ...For those who use more than one email account, must use the one you > entered when you signed up to this list when > sending > a post to this list
[AMRadio] Re: Mic Sharing
The benefits of this circuit are that all I/O's are balanced, and the output chips can be forced to run into an unbalanced input by grounding one side, if need be, without damaging the chip. This keeps the grounds floating between the mixer and the xmtrs (like a transformer), which may (or may not!) help keep ground loops at bay. Also, this circuit is DC coupled all the way thru and will pass a square wave. This means you can drive the inputs with highly processed, even clipped, audio and what goes in also comes out. Finally, having multiple inputs may be handy for some folks. If you don't want that, just eliminate the multiple input stages and gain stage. Of course you could just use op amps to drive the rigs unbalanced, too. 73, Gary W3AM N0DBX wrote: > >Darrel: > > > >Here's a link to a schematic I just did of a mixer/distribution amplifier that > >would do what you want, and more: > > > >http://www.w3am.com/W3AMmixerDA.jpg > > > >Low parts count and excellent fidelity. All balanced I/O. > >Does this help? > > > >g > > TNX. We're getting in the ballpark. Still thinking and figuring what levels > I need for the various rigs, etc. Have found several ideas in the area of > Op Amps. Somebody did this a few years back and think it was in QST, > but can't find it. It was for modern transceivers, of course. I suppose it > would be easiest to tailor an amp for each rig and then tie them together > in the inputs. I'll study W3AMs data a little more. That site had escaped > my searches. > > I need a little gain on the main AM rig, but not on the new stuff. Gain would > probably make it easier to stay away from hum. The possibilities for ground > loops abound! I'm still rolling it over in my mind and appreciate the input. > > Darrel
Re: [AMRadio] Mic Sharing
Darrel: Here's a link to a schematic I just did of a mixer/distribution amplifier that would do what you want, and more: http://www.w3am.com/W3AMmixerDA.jpg Low parts count and excellent fidelity. All balanced I/O. Does this help? g Darrel Nichols wrote: > ...if you did a schematic that is Emailable, that would really be great. > > N0DBX
Re: [AMRadio] Mic Sharing
Darrel: There's no need to worry about 'matching' a hi Z input impedance with the 'virtual ground' low source impedance of an op amp. It'll love it. The only real issue is what peak voltage the stage needs to provide. For solid state rigs, it'll be fine, since they're expecting low voltages as well. For most single ended tube line input stages, like a 12AX7, etc., the +/- 15v or so a typical op amp is capable of will also be just fine. Depends on the gain structure thru the modulator. Certainly for a mic preamp input you'll have plenty of steam, in fact you might consider eliminating the mic preamp stage and going into the next gain stage in the rig. As for isolation into tube stages, you should only need a coupling cap to keep the bias voltage off the opamp output. You could also use transformers, of course, but that's not really necessary. The only problem that might arise by feeding all these different radios like this is potential ground loops. Besides transformers, there are balanced line driver stages that you could use, like the Analog Devices SSM2142, ( http://www.analog.com/Analog_Root/productPage/productHome/0%2C2121%2CSSM2142%2C00.html ), tying one leg of the balanced output to chassis ground of each xmtr. But if all your chassis are ground bonded together, it probably won't be a problem. I wish I had a quick schematic for you. I'll look around to see if I can come up with something. 73, g Darrel Nichols wrote: > Of course I'll build it. I guess I could rephrase the question further. > I'm trying > to figure out how to feed the vintage gear (Viking II, S-Line, HT-44, etc.) > with > something like an OP Amp. I had hoped someone had tried this. Getting the > output up into the megohm range needed might get a little dicey. If someone > has gone here before, I'd like to hear about it and if you did a schematic > that > is Emailable, that would really be great. > > N0DBX
Re: [AMRadio] Mic Sharing
Hey Darrel: I'd suggest using a common mic/preamp/processing chain, feeding a multiple-output distribution amplifier to feed your various rigs, each output having its own gain control. The only anal detail I'd want to be sure about is that the amp is phase linear with no tilt, overshoot or ringing, as you'll be driving it with peak limited, and perhaps intentionally clipped, waveshapes that you'll want to preserve. You could easily build you own, as well. 73, g Darrel Nichols wrote: > I know somebody is doing this, but haven't found any references around. > I want to use a dynamic low-z mic with several rigs including modern > transcievers > and the tube gear. Both AM and that other mode...Any suggestions on outboard > processing circuits that will match multiple rigs, both hi and low Z? > Perhaps with > adjustable gain for each one individualy? This is an info expedition so any > ideas > would be appreciated. I want to use a single boom and clean up some of the > mess > around here! > > Darrel, NØDBX
Re: [AMRadio] Re: looking for linear amplifier
Hey, Jim. Merry Christmas. If that's what you really want, the answer is a Class E PA with PDM. http://www.classeradio.com/ g Jim Bromley wrote: > > ...Will it fit on my desktop and weigh less than 100 lbs? > :-)
Re: [AMRadio] Looking for Linear Amp
Paul: Others have answered your question about Class C RF amps vs. Class AB linears. You can certainly use your Ranger to drive an amp like an SB220 for fully modulated AM at ~400watts carrier. Enough to make you a 'big gun'. BUT, you'll have to either modify the Ranger to permit reduction of its output to ~10-20 watts (variable screen voltage is one way), or attenuate the output accordingly. I much prefer the former method as it allows much better modulation performance and takes a load off the Ranger final. Using linears for AM like this is purely a convenience approach, as linear amplifiers are plentiful out there at reasonable cost. High level, high power AM transmitters are not. Using a linear is a legitimate way to get on quickly an start enjoying AM with a decent signal. You can 'move up' to big iron later if you like. But you must be very careful about how the exciter (Ranger, etc.) and linear are adjusted and operated. You can quickly blow something up or, worse, operate with a terrible on air signal and not know it, eating up wide chunks of the band causing SSB'ers to curse our lot even more. Before buying an amplifier, I'd suggest an oscilloscope to monitor your signal and become intimate with what's going on. Good luck! 73, g Paul Sokoloff wrote: > > Hello again, > I had no idea I was going to stir up such an interesting discussion. I > was the person who originally posted this. After reading all of the replies > and as a newcommer to this, I have one question. If one needs an 800 watt > amplifier to run 100 watts AM, then how does a Viking with 3 small 6146s run > 125 watts AM? > I have a Johnson Ranger (45 watts with one 6146) which I wish to drive > an amplifier for more output (maybe 125 to 150). Should I just get a viking > 2 or an amplifier? Does anyone have an amp they are interested in selling? > Thanks, > > Paul WA3GFZ
Re: [AMRadio] AM from a ricebox
Hey Don: FWIW, if you spend any time on the road, put the rat shack 10M rig in the car with a 100w footwarmer and hang out in the 10M AM window between 29.000 and 29.100, where intelligent life is often reported. Being incarcerated in condo life here, it's all I have for AM these days and it works pretty well when the band is open. Gary W3AM Donald Chester wrote: > > > ...I found the same thing when I bought one of those little Radio Shack 10 m > transceivers a few years ago
[AMRadio] RCA BTA-1R1 Available in Washington State...
FYI, The estate of K7OVN has an RCA BTA-1R1 AM transmitter in his old garage and it needs to go now so they can sell the house. Pickup on location only in Chehalis, WA. If you or anyone you know might have an interest, let me know and I'll forward you the contact info for his sister. This should be a great rig for someone. 73, Gary W3AM
Re: [AMRadio] Requium for Tranny?
Dave: Ouch. Sorry to hear that. Sounds like WZ1M's offer to rewind might be attractive, unless you can find another 500 xfmr somewhere (good luck!). That's a great rig so it's worth the investment. Now, to find out why it went bad in the first place... Best of luck. Gary W3AM Dave Aabye wrote: > > Hello Gary, > > Thanks for the suggestion, which I believe has proven to be conclusive. > > I hooked my Variac to the primary and slowly increased the secondary voltage. > The caps were disconnect from the rectifiers, so the transformer was "all by > itself". At about 700 volts, the voltage started to jump just a bit. At > maybe 750 v, the secondary emitted a puff of smoke with an accompanying hiss. > > I think it is clear that the transformer is shot. Time to call Peter Dahl! > > Again, thanks for your input. > > 73 de Dave
Re: [AMRadio] Requium for Tranny?
If you have an audio oscillator and ac voltmeter handy, inject 60Hz at 1V into the primary and measure the secondary. That should help you see if there's a ratio/shorted turns problem. Next would be to slowly bring the xfmr up to full input voltage with a variac, with a light secondary load. If it survives the voltage test then the trouble is likely in the load somewhere (rectifier, etc.). g Dave Aabye wrote: > > Good morning all, > > I need some advice. > > Earlier today my Viking 500 tripped off with the familiar odor that we > have all come to dread. I only lost HV. > > After I got the cover off the PS-Mod unit, I was surprised to see > nothing unusual. Then I started sniffing, and that led me to the HV end > of the plate transformer. I removed the end cover and again saw nothing > unusualonly the odor, which by then was beginning to dissipate. > > Resistance measurements lead me to think that some windings may be > shorted. One side to center tap reads 110 ohms. The other reads 95. > The manual says 100 on either side. The HV secondary shows infinite > resistance to ground, but that is with no juice applied. > > What I'm wondering is whether the 15 ohm difference is conclusive. If > not, what other tests might I make without risking further damage? > > Thanks in advance for any advice, > > Dave, W4QCU > Oak Ridge, TN
