Re: [AMRadio] AM from what I have in the junk box
My PDM-AM rig uses a single 833A as the modulator... -Larry/NE1S Geoff/W5OMR wrote: > > Subject: [AMRadio] AM from what I have in the junk box > > > Anyone have any nice schematics to construct a AM transmitter from some > > 4-125As or 4-65As that I have available?? Also have a new 833a that > > could be used for a modulator. > > you need more than one tube for a modulator... > > ...usually > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
[AMRadio] Re: Home Brew
Cathode modulation works best with triode RF finals. With testrodes you end up with mostly grid modulation because of the (much) higher gain of the grid-cathode circuit. The 50's handbooks (Left Coast & ARRL) explain this. I presume high-mu trodes probably have the same issue. Last spring I experimented with a grid modulator (inserted in the cathode circuit) of a class C 807 PA. Worked well, but only about 7W of carrier out (about what you'd expect from an "efficiency-modulated" 807). 73, -Larry NE1S Crawfish writes: I am trying to figure out how to cathode modulate the 4-1000 I have. I have a pair of 813's and have a 4-125. Have a bunch of 807's and 1625's as well. Joe W4AAB
[AMRadio] Re: B&W 5100B Audio Mods
i am not familiar with the 5100B, but I would be VERY surprised if the screens weren't modulated as well as the plates - it is absolutely necessary to achieve 100% modulation of tetrode, pentode, or beam-power calss C RF stages. This is usually done with this class of transmitters (~100W commercially-manufactured ham AM rigs)with a screen droping resistor from the modulated plate supply. It can also be done with a dropping resistor from the unmodulated B+, or an audio choke from a voltage source equal to the desired screen voltage; in these cases, the screens self-modulate. GL, -Larry/NE1S Tom Elmore writes: Does, anyone know of a source for audio mods for the B&W 5100B transmitter. I wonder if anyone has tried to modulate the screens in addition to the plate of the finals. It appears the screens use a different power supply than the plates of the finals. Thank You Tom Elmore KA1NVZ Anchorage Alaska __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: Low Power AM nets
Hi Al, With QRP AM, it's not so much a matter of what frquency, but band conditions. You are unlikely to have much luck, for example, after dark on 75M or after early afternoon on 40M. But during mornings on 40M, or daylight hours on 75M, you should be able to make many enjoyable contacts with your DX-60. Don't worry about being "ridiculed;" anyone doing that isn't worth worrying about anyway. But it would be considered a bit inconsiderate to make others try to pull you through the mud when conditions are not conducive to low-power operation. Anywhere in the fone bands is fair game, but you are most likely to find other AMers to talk to in the so-called "AM windows" (let's not start another thread on this, though!). Look between 860 - 3890 on 75M and 7285 - 7295 on 40M. There is also often AM activity on 3825 and 3837. The AWA AM net meets Sundays at 4:30PM EST on 3837 - please join us. A bunch of us on the east coast (myself included) have built and regularly operate AM transmitters in the 1-10W output class. -Larry/NE1S Schichler, Alfred writes: I was wondering if there are any nets, or just parts of the 75 or 40 meter bands where I could find anyone on low power AM, preferably controlled-carrier, screen-grid modulation. I recently got a DX-40 / HQ-100 AM Station on the air, for nostalgic purposes, but it seems like the only AM stations I usually hear are ones with high-power, high-quality plate modulated AM, and I don't want my puny signal to be just lost in the crowd or ridiculed. (Not that that would necessarily happen, but it seems like a possibility). I haven't listened at all hours of the day or anything, but I haven't found what I'm looking for. I would appreciate any info on this subject. Al, NE2D __
[AMRadio] Re: B&W 5100B Audio Mods
Wow, talk about snail mail! I had originally sent this to the list on Oct 24!!!. -Larry/NE1S Larry Szendrei writes: I think it would have to be, Tom. Then there should be an audio choke between the screen supply and the screens. -Larry/NE1S Tom Elmore wrote: The unit I have has a separate B+ supply for the screens. So would this be self-modulating then? -Tom
[AMRadio] Re: Xtal mike?
Hi Steve, What was the question :>) -Larry/NE1S [EMAIL PROTECTED] writes: Hi all: My restoration rig requires a crystal microphone. Your reply is appreciated. Tnx, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: Mike
Steve, I'd put a 4.7Meg to 10Meg resistor from the 1st 6SJ7 grid to ground. A crystal mike wants to work into a (high value) resistive load. GL, -Larry/NE1S -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Tuesday, March 15, 2005 9:25 AM To: amradio@mailman.qth.net Subject: [AMRadio] Mike Thanks Guys: This mike is for a vintage 1948 AM rack rig homebrew by W2PLY who moved into Senior Residence. The speech amplifier/modulator schematic is right from August 1947 QST. I got the rack and the 5 sections directly from the flat bed trailer at the estate sale...and now just about finished doing what very little fixin required. The article cites a crystal mike; it feeds directly into the grid of a 6SJ7 with no grid leak resistor. As I understand these things, the mike - what type of cartridge - needs to put out 'so many' microvolts necessary for the tube into which it feeds. And the impedance needs to 'match'. I understand there plenty of gain after the 6SJ7...and one of the 6SN7's has a "tone control" potentiometer in the grid. Personally, my voice is a little higher from center in pitch..and I'd prefer more lower than higher freq. response...which is generally a problem due to low freq. rolloff in the mike curves...that's why I'm eager to try this 'tone control'. I guess the first question is: what impedance number is required for a 6SJ7 grid? Your generous help is always appreciated. Regards, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: Petition Pending
Right on, Todd. -Larry/NE1S Todd, KA1KAQ writes: On 6/21/05, Anthony W. DePrato <[EMAIL PROTECTED]> wrote: > incentive licensing is a joke and no longer serves any useful > purpose. Plus, from the outset, it never achieved its original purpose: > to improve the technical expertise of the amateur community. > >Don K4KYV SNIP AMEN !1 A lot of folks complained that CW was only meant to keep people out who would otherwise be great hams. Other than the aspect of CW getting through in times of emergency when nothing else would, I always saw it as more of a test of someone's determination to become a ham - not their knowledge of electronics. If you have to work for something to acheive it, you're much more likely to do so because you *want* to do it, not simple because it's available to you if you want to bother. When the Amateur Radio Retail Lobby was producing all of those articles in QST in favor of the No-Code techs (Mike and Wally or whatever), it was clear that their intention was to sell more stuff, not to benefit ham radio in general. The constant inclusion of lines like "Mike became a ham by using the ARRL's Now You're Talking manual" or "he was able to find such and such by using the ARRL Repeater Directory" or "Wally's wife is studying for her license with the ARRL License Guide" and so on served to praise the No Code techs while bashing the OTs for not being understanding or compasionate enough to give the new guy a chance. Really, they were nothing but than more ads. A few years after the No Code craze there was an article somwhere with numbers of those still involved after getting licensed. No Code techs had the lowest renewal rate, IIRC. My theory is, when you hand a person something instead of making them work to earn it, they're a whole lot less likely to really want it, muchless appreciate it. And while I was licensed under the incentive licensing scheme and it did work to spur me on, I'd much rather see a real exam to test someone's knowledge and determination to be part of ham radio rather than a multiple guess format that can be memorized with enough time. Those little diagrams I had to draw to demonstrate my knowledge of a certain circuit didn't scare me away or scar me for life. I also think they only thing that will 'save' amateur radio will be more hands-on involvement by active hams giving something back through public service, school visits, or other demonstrations. Giving away licenses hasn't done it, and won't. Today's radio gear resembles the computers, video game consoles, cellphones and stereo gear kids use on a daily basis, so even that is a tough sell. Show them some glowing tubes and meters with needles dancing around and their eyes light up. Something about sending your voice across the country or around the world without the aid of connected wires still has appeal. You're not going to get every kid, or even a lot of them, but when was that ever the case? ~ Todd, KA1KAQ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Re: need help
With a 50 ohm grid load on 4-400s, I think you'll find you'll get very little amplification from the stage - the 40400 grid(s) want(s) to see more voltage. I went throught this exercise one (on paper), so went with a 1:16 balun into a 800 ohm non-inductive resistor network in the actual design. Problem was, I couldn't make it broadband enough to cover more than 3 consecutive bands at a time, and finally resorted to a T network on the input, loaded with about 2000 ohms worth of resistors. -Larry/NE1S Gary Schafer writes: The input impedance should be very near what the value of the resistor is. In this case 170 ohms. The 4-400's will most likely be run in AB1 so no grid current. I would put in a 50 ohm resistor instead. You should get enough drive with it. Figure what the bias voltage will be on the tubes. Then figure what the peak voltage will be from the exciter at 50 ohms. If the peak voltage will be greater than the bias voltage on the tubes then you have enough drive. 73 Gary K4FMX -Original Message- From: [EMAIL PROTECTED] [mailto:amradio- [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, October 19, 2005 10:46 AM To: amradio@mailman.qth.net Subject: RE: [AMRadio] need help I'd have used an MFJ 259B to actually measure the input Z. Alternatively, you can always use a small tuner to "tune" the input. I do that anyway with my Drake L4B, (use a small MFJ mobile tuner with meter). 4-400's, eh? Nice amp! If your plate voltage is high enough, you ought to get serious power out of that baby! 73, Ed, VA3ES From: Edward B Richards <[EMAIL PROTECTED]>: I want to drive a linear amplifier with a rice box that requires a 50 ohm load. The linear amp uses an input to a 170 ohm, 80 watt swamping resistor to ground, then through a .001 mfd capacitor, then through a VHF parasitic suppressor consisting of 4 turns of wire around a 47 ohm resistor, to the grids of a pair of parallel connected 4-400A tubes. What I need to know is the impedance of the input. Is it close to 50 ohms or do I need to use a matching network between the rice box and the linear amplifier. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
[AMRadio] Re: 75m early
Hmmm... Geoff, I'll assume you're in the Central time zone. If so, 1AM Pacific time should work out to 3AM Central. So you may not have to miss Letterman after all. 73, -Larry/NE1S W5OMR/Geoff writes: 1AM Pacific time is 11pm here.
[AMRadio] Re: Need list of good AM radios to start lookingfor.
On the Ranger accessory plug are available LV B+ (~300V), HV B+, and each secondary lead from the mod tranny. You can simply rewire a new plug to hook the "bottom" of the mod xfmr secondary to LV B+, or, you can do as I did: mount the plug in an aluminum minibox along with a SPDT switch rated for the voltages involved to switch the bottom of the mod xfmr secondary between LVB+ and HV B+. The entire minibox assembly splugs into the acessory plug on the back of the Ranger. Make sure you ground the minibox to the ground pin on the accessory plug, for safety's sake. Works FB, got the idea of using the LV B+ from Timtron. Ranger puts out ~12-15W of carrier when running the PA on LV B+, perfect for driving an amp, and no power wasted in a big honking resistor. 73, -Larry/NE1S John E. Coleman (ARS WA5BXO) writes: You are correct of course Jim. I would mount the resistor in its own case and construct a cable so as to plug the modulator into the new chassis with the resistor and bypass cap, and then the new chassis would plug into the Ranger. To conserve power and heat, another power supply with lower voltage output or variable output would be better. But some time you do with what you have and if the 2000 ohm 50 watt resistor is handy and you have an old scrap chassis well there you go. I once needed a stiff bias supply so I used a single diode and 400 uf filter right off the AC line. Then I placed a 100 watt lamp in series with a large variable 100 ohm 100 watt resistor to ground. Not a very efficient thing to do but it did hold the bias steady on the 805s modulator. This was long before I had access to the HV transistors, ETC. John, WA5BXO
[AMRadio] Re: Valiant and Loop progress
John, I'm working on a Vaiant* for a friend, and I ended up using eight 680pf @ 1KV in series-parallel (4 parallel pairs in series). The caps I used were the CDE "snubber" caps, available from Mouser. Between these and the analogous 40 meter fixed caps, it the total was around $60. But, they are working well - no flames, smoke, or bad odors :>) 73/GL, -Larry/NE1S *FrankenValient John Lawson writes: So the Valiant is putting out 100 - 130 watts into my load or antenna on all bands - I put it back in it's cabinet (mistake..) and cabled it up. Having previously set the mod bias, I tuned 'er up, opened the Audio pot, gave a couple of whistles and the 160/80 M capacitor stack "deviated from spec" in a rather spectacular and stinky fashion. O well - at least I understand completely what needs to be done - and about $60 worth of the correct RF units will be delivered to me on Tuesday. Wouldn't have been so much, but I bought heavier than required and also spares, just in case
[AMRadio] Re: Valiant and Loop progress
For the uninitiated, what's "EMT?" I think I've figured out it's not "Emergency Medical Technician" in this context. -Larry/NE1S W5OMR/Geoff writes: The other alternative is to get a few joints of EMT. They come with one end threaded and are joinable, end-to-end. Drill a hole at the top, add a couple of pulleys, yank up them antennae!
[AMRadio] (no subject)
Last Saturday nite I was down in the cellar shack, working on building a PP 805 modulator deck for a 1930s open relay-rack transmitter I'm restoring that, to the best of my knowledge, never had a modulator. I tuned around 75M and 160M looking for some AM QSOs to monitor, but I couldn't find any with signals good enough for comfortable listening (which is a rare occurrence up here in the Northeast). So I switched the old Meissner RCVR to the AM broadcast band, and tuned across 770 Kc/s WABC - a talk radio station for the past 24 years, but before that the quintessential AM "contemporary" music station. And what I heard was not talk radio, but a live show with a real DJ/commentator spinning the old tunes! From what I gathered this is a new show, and there were all kinds of folks calling in giving their praise. And in one segment was a live Neil Sedaka (sp?) interview! It was like being caught in a time warp. Some of my fondest childhood memories are of hanging out in my grandfather's cellar in Chatham, NJ building, fixing or otherwise diddling with some radio with WABC cranking the tunes. I now know how I'll be spending my Saturday nites for the foreseeable future. 73, -Larry/NE1S
[AMRadio] Re: WABC oldies show
Hi Chuck & list, I think the show is from 7-10PM, or maybe 8-10PM, EST, Saturday nite. And yes, they play the old jingles too. (I think you can download .wav files of many of the jingles from http://www.musicradio77.com/) You should have no problem hearing them. People were calling in from as far away as Georgia and Chicago (under the shadow of WBBM at 780, even). -Larry/NE1S Chuck Kembring writes: Larry... Thanks for that post. When I was a kid in Philadelphia, hanging on the corner with the crowd, I would often listen to "Seventy - Seven, Double U - A - B - See!" when the conditions were right. I can still hear that Jingle in my head! (Almost 60 years old - Next April) I will give a listen and see if I can hear it out here in Southern Chester County (Pa.) Ah, - The good old days 73, Chuck WB3LGG Cochranville, Pa.
[AMRadio] Re: GB> Re: 770 WABC Real Radio show
Hi again, Kim & lists, Yes, I found them on a trip out to the AWA conference (Rochester NY) a few years back. They often come in well here in Maine, after dark of course. As does WKBW (or is it WWKB :>)) in Buffalo. Both great stations, for sure. 73, -Larry/NE1S Kim Herron writes: Hi Larry!! Well, if nobody else has yet informed you, put on your list of AM radio to be sought after, AM 740 CHWO, out of Toronto Canada. They run the similar format all week long. Its a combination of Big Band, Solid Gold, 50's and 60's rock and roll, Pop (Sinatra, Dean Martin etc) and so on. They even run an all request night. They go omni-directional after sundown and I get them gang busters here in Western Michigan. They run the same format all day as well I believe, But I can't get them to know for sure. _ This message scanned for viruses by CoreComm Thanks!! Kim Herron W8ZV 1-616-677-3706 Outgoing mail scanned for virus and worms with McAfee Virus Scan
[AMRadio] Re: reply to SSB interference
Hi Brad (and group), While I don't necessarily disagree with you (and certainly not your motive), we have to be aware of the fact that in-fighting among amateurs in front of the FCC makes us ALL look bad, in their eyes. Too many complaints, even if they are all justifyable ones, will make the amateur radio service look more and more like a PITA to the FCC, who barely has enough resources anymore to deal with only the most blatant, destructive, offenses. OTOH, I can't offer any solution for dealing with these guys other than ignore them & hope they go away. 73, -Larry/NE1S UVCM INC writes: To the group, This is what we need to do as a TEAM, see FCC letter below) monitor all persons INTERFERING WITH Qso's and our net. This is willful disregard for a legal approved emission of operation (AM), willful jamming or interfering with us can be handled through the FCC. We need to have some of our fellow operators who have time, (sent up monitoring times), document, voice record and one person ask them nicely to move, explain why, and if they resist, file complaints with the FCC, ARRL and any other group that will listen or will publish the complaint. We need to PUBLISH, there calls, and any other information (of public record) of there, on web sites, and in as many printed materials as possible. Theses operators are bad apples and are committing illegal acts. Embarrass them, into doing the right thing, and then if needed as a team, with all the signatures possible, send the complaints to the FCC. If action is slow, each of us send a letter to the FCC weekly until we action. We need to hit them were it hurts, IN PLAIN VIEW OF FRIENDS, CLUBS THEY BELONG TO AND THE COMMUNITY WHERE THEY LIVE AND WORK. No insults, or threats, sweet and to the point, the legal way, the way the FCC and other would respect. Thanks, one option only Brad KB7FQR
[AMRadio] Jack Holzer (?) please contact me
I apologize to the lists for the bandwidth, but... Jack Holzer - I have been trying to respond to the Email you sent me, but they always bounce back. I am sending to "[EMAIL PROTECTED]". Maybe your spam filter is not letting me through? (Never sent any spam, although I was a memberr of SPAM - Society for the Promotion of AM - back when that organization was active!) Thanks!!! -Larry/NE1S
[AMRadio] Push-pull Triode HF PA layout question
Hello all, I humbly request the experience-based advice of this esteemed group. Background: I am working on a project, part of which involves completion of 1930s Push-pull trode PA deck for 80M - 10M. Notice I said "completion," not "construction." This deck already has the plate tank components, tube sockets, and neutralizing capacitors mounted on a beautifull black-wrinkle chassis & panel. The axis bisecting the holes for the tubes is parallel to the front panel, the plate tank air variable (split stator) is perpendicular to the front panel, and the plate tank coil (plug-in jack-bar style - actually I'll be using BC-610 coils, link-coupled to the antenna) is centered directly behind the plate tank capacitor, with its axis parallel to the front panel. What this deck lacks is a grid tank circuit, which I need to add. The tubes will be 812s or T-55s, and will be plate-modulated for 250 - 300W output. Question: What is the worse sin: lack of physical symmetry, or proximity of the gazinta to the gizouta? It seems that I'll have to compromize one or the other in adding the grid tank circuit, based on the present layout. The grid tank will be link-coupled to the exciter. Thanks for your assistance, -Larry/NE1S
[AMRadio] Re: Push-pull Triode HF PA layout question
Thanks, John. I'll make a posting after I've implemented and tested what I conclude will be the best comrpomise. 73, -Larry/NE1S John Coleman ARS WA5BXO writes: Construction of a push pull circuit is a real difficult project if started wrong. It has been my experience to find that the plate tank and grid tank do need to be as far apart as possible if plug in coils are to be used and they need to be at right angles to each other. Some folks choose to use a band switched coil arrangement where the grid coils and switch assembly can be in a completely shielded case of its own or below the chassis that is sealed up for RF. I have actually used a Johnson Match Box 500 as a grid drive circuit years ago. It sat on the desk and I used that 300 ohm shielded cable that Radio Shack, sold years ago, to feed it to the grids. I put two RF chokes in the Match Box to attach the grid leak resistor and bias supply to. It worked quit well. I remember I could adjust the length of the twin lead cable to get better results on some of the higher frequency bands. I prefer the switched coil assembly in a shielded box and mounted under the chassis myself. You may find more ideas at http://wa5bxo.shacknet.nu/wa5bxo.qsl/pptriodes/pptriodes.htm Good Luck John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ne1s Sent: Monday, February 06, 2006 2:31 PM To: AM Radio Reflector; [EMAIL PROTECTED] Subject: [AMRadio] Push-pull Triode HF PA layout question Hello all, I humbly request the experience-based advice of this esteemed group. Background: I am working on a project, part of which involves completion of 1930s Push-pull trode PA deck for 80M - 10M. Notice I said "completion," not "construction." This deck already has the plate tank components, tube sockets, and neutralizing capacitors mounted on a beautifull black-wrinkle chassis & panel. The axis bisecting the holes for the tubes is parallel to the front panel, the plate tank air variable (split stator) is perpendicular to the front panel, and the plate tank coil (plug-in jack-bar style - actually I'll be using BC-610 coils, link-coupled to the antenna) is centered directly behind the plate tank capacitor, with its axis parallel to the front panel. What this deck lacks is a grid tank circuit, which I need to add. The tubes will be 812s or T-55s, and will be plate-modulated for 250 - 300W output. Question: What is the worse sin: lack of physical symmetry, or proximity of the gazinta to the gizouta? It seems that I'll have to compromize one or the other in adding the grid tank circuit, based on the present layout. The grid tank will be link-coupled to the exciter. Thanks for your assistance, -Larry/NE1S __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: FS: restored Gonset G-76
Can't comment on the stock G-76 or it's audio, but the triode connection on the 6DQ6 modulators is a perfectly valid & workabel, if uncommon and poorly documented, mode of operation. I have used such a connection with 6146's - audio input to screen grids, with control grids either grounded or just a few volts negative - in an Apache, and a Viking I (which can be heard on the east coast every Tuesday nite on the Gray Hair Net on 1.945 MHz), and in this mode the tubes are capable of much cleaner audio than they ever would be connected as beam-power tetrodes. The downside is they require more drive. 73, -Larry/NE1S Brett gazdzinski writes: And the TX audio sucks (surprise!). The audio driver transformer (also the receive audio output trans) is a weak point, as are the crazy triode connected (audio to the screens) 6DQ6 modulator tubes (zero bias). No specs for a 6DG6 as a zero bias triode connected using the screens
[AMRadio] Re: AM Transmitter Advice??
Donald Chester writes: Assuming one is going to build a linear, and so putting aside other issues such as linear vs plate modulation, why do you think it makes a difference what tube is used? Are you referring to running a linear at greater than legal limit?. Well, go ahead and try building a legal limit linear that runs a pair of 807's in the final. Yeah, or a pair of 866As Sorry (the devil made me do it). 73, -Larry/NE1S
[AMRadio] 1930's Old Buzzard Open Rack Transmitter Finally Sees the Airwaves! (Long)
Hello, Some of you may remember that a few weeks ago I posted a question regarding optimizing the layout for a push-pull triode HF final deck, given that the deck in question was already partially built (by someone else). This was a component of a larger project involving completion/restoration of a 1930s vintage homebrew open-relay rack AM transmitter I had initially acquired some 15-20 years ago, and has been sitting patiently in my cellar shack since this time waiting for me to ge a round tuit. Well, the elusive and highly-coveted tuit finally arrived about a year ago, when I started drilling and blasting for the modulator deck. I had to take a rather long break from itarting last July, when I started a major effort to bring a majorly-hacked Johnson Valiant back from the dead for a friend which led to the birth of FrankenValiant. But thats another story for another time. With FrankenValiant finally completed, I finally got back to the project at hand a month ago, and to make a much longer story less so, the transmitter made its maiden voyage on the airwaves last Sunday evening, when I used it during the final 2 hours of the AWA AM QSO party, on 75M. The final presently uses a pair of 812s, which are modulated by a pair of 805s. When the debug/shakedown stage is over Ill switch over to T-55s in the final (harder to find, and more expensive, than 812s). There are still a few problems, which I hope to rectify next weekend: (1) My bias supply for the modulators and finals, built onto the modulator deck, failed. I had used a period resistor from the junkbox it was working, now its opened up. Replacing it will involve removing the modulation transformer from the deck (to make the weight more manageable, removing the deck from the rack, replacing the resistor, and assembly in reverse order of disassembly. So my on-th-air use was with grid-leak bias only on the finals, and zero-bias on the modulators (the 805s were still operating within their ratings, though). (2) The speech amp has an intermittent noise which modulates the finals quite nicely when it is present. No surprise: all the caps in the deck are original wax-paper. I did check the DC blocking caps for leakage beforehand (by measuring the DC grid voltages), but guess I shouldnt have trusted them. A little benchwork with the scope should trace down the faulty component. Its in the first stage, cuz its intensity varies with the mic. gain control. I actually saw it on the scope when I was checking out the speech amp initially, and made a conscious decision to deal with it later. (3) The link output is directly feeding coax which directly feeds the antenna tuner, and I can only load the finals up to ~150 mA for about 160W output. Should be able to load them to nearly twice that. I need to install a series breadslicer to resonate the link. (4) I need to improve the grid drive on 10M. (5) I want to use a spare set of relay contacts to disable the speech amp (by removing the B+) on standby (receive). And, finally (pun intended), I would like to thank all those that answered my question concerning the layout of the final PA deck. If youll recall, What I had to work with was the two tube sockets mounted parallel to the front panel, with the output tank 2-section variable capacitor mounted perpendicular to the panel between them, and the final tank coil jack bar parallel to the panel, near the back of the chassis. The plate tank is all above-chassis. There was no grid tank, and I was puzzling over the best way to add it. I ended up putting the grid 2-section variable cap centered below the chassis with its shaft protruding through the front panel. I mounted the 5-pin socked for the grid coil a few inches behind that, also below the chassis, so that its axis was also perpendicular to the panel (and therefore also to the plate tank coil). I had to be careful where I put these, not only for the obvious electrical design considerations, but also because the cap rotor (when fully open) and coils (when plugged in) extend below chassis, and into the area of the exciter deck. But the grid coil is also perpendicular to all the coils in the exciter deck. Its not a perfectly symmetrical layout, but its pretty close, and I was able to neutralize it using the 10M coils. Engineering is full of compromises, and if You've made them correctly AND youre lucky it works when youre done. I seem to have been lucky, at least... 73, -Larry/NE1S
[AMRadio] Re: 1930's Old Buzzard Open Rack Transmitter Finally Sees theAirwaves! (Long)
Thanks for the kudos, John! Could you or done describe the protective bias circuit you refer to? Probably could figure it out, but the group may be interested as well... 73, -Larry/NE1S John E. Coleman (ARS WA5BXO) writes: CONGRADULATIONS A JOB WELL DONE! I really like the choice of tubes. I don't know what a T55 is but probably one of the special Taylor triodes with 55 watts plate dissipation. Probably not a lot different than the 812s but I know that the 812s are very good tubes to use in a class C plate modulated rig especially if used with 100% grid leak bias or the configuration that Don, K4KYV, uses where there is a safety bias supplied thru a diode and the diode becomes reversed biased when RF drive causes grid leak bias. The 100% Grid leak bias DOES make a difference in the modulation characteristics of the rig. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ne1s Sent: Tuesday, February 21, 2006 2:27 PM To: AM Radio Reflector; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: [AMRadio] 1930's Old Buzzard Open Rack Transmitter Finally Sees theAirwaves! (Long) __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: 1930's Old Buzzard Open Rack Transmitter Finally Sees theAirwaves! (Long)
Sorry!!! That was supposed to read "Could you or DON describe the protective bias circuit you refer to? " -'1S ne1s writes: Thanks for the kudos, John! Could you or done describe the protective bias circuit you refer to? Probably could figure it out, but the group may be interested as well... 73, -Larry/NE1S John E. Coleman (ARS WA5BXO) writes: CONGRADULATIONS A JOB WELL DONE! I really like the choice of tubes. I don't know what a T55 is but probably one of the special Taylor triodes with 55 watts plate dissipation. Probably not a lot different than the 812s but I know that the 812s are very good tubes to use in a class C plate modulated rig especially if used with 100% grid leak bias or the configuration that Don, K4KYV, uses where there is a safety bias supplied thru a diode and the diode becomes reversed biased when RF drive causes grid leak bias. The 100% Grid leak bias DOES make a difference in the modulation characteristics of the rig. John, WA5BXO
[AMRadio] Re: 1986 AM Ham-radio Video
I still have my VHS copy from 20 years ago, too. I most recently watched it with a friend (W1UJR) a couple of years ago. -Larry/NE1S Jim candela writes: Hi All, My son Paul just transferred the old SPAM (Society for the Preservation of Amplitude Modulation) VHS video tape to a digital AVI file. This was circulated to me by the late Floyd Dunlap, WA5TWF. The video was produced by Dave Ramser KG6AB and Norm Scott WB6TRQ. This video was very well done. I really enjoyed the interview with Mr. EF Johnson. My copy was on a 20 year old tape recorded on low speed so the quality is a bit lacking, and a high degree of video compression results in a noticeable lip-sync offset.
[AMRadio] GB> RCA BTA-250L Broadcast Transmitter Longview TX (fwd)
Reposting from Glowbugs list per Patrick's request. Please contact the seller, not Patrick or me, if interested. Apologies if someone else has already passed this along to the list. 73, -Larry/NE1S Patrick Jankowiak wrote: Could someone please post this to the AM radio list and the ham radio usenet newsgroups? I have no access to those. Thanks, Patrick Jankowiak wrote: This is not mine. Please do not reply to me about it.. It is the same model as one I have: http://www.bunkerofdoom.com/kd5oei/bta250L/rcabta250L.html http://www.bunkerofdoom.com/kd5oei/shack/20060201/index.html It needs a new home because the classic "thunderbird" car has to go in the garage. Be sure to ask the owner, below, any questions about it. I have never seen it and know nothing about it, just helping him to get it gone from his house. === for sale: RCA BTA-250L AM broadcast Transmitter, easily convert to 160M ham band. High fidelity push pull plate modulated AM rig. With manual and blueprints. Just check out some of the specs.. Carrier output power 250 watts Frequency 540 to 1600KC Stability +/- 10Hz (internal ovens) Modulation high level class B AF input +16dBm (100% modulation) AF Response +/- 1.5dB 30 cycles to 10 kilocycles AF distortion less than 3% RMS 50 cycles to 7500 cycles Hum and noise 60dB below 100% modulation RF harmonics level less than 0.05% (-33dB) Carrier shift less than 5% from 0 to 100% modulation Power requirements 105 to 115VAC 1625W program, 1825W 100% mod. It's for pickup, or you-arrange-pack-n-ship. Contact the owner: SCOTT RICE 903-720-0184 Longview, Texas
[AMRadio] Re: 1986 AM Ham-radio Video
Hi Jim, I, unfortunately, don't have the facilities to make a VCD or DVD. If you would like to try, I'd be happy to lend it to you. But I don't recall the video quality was anything to write home about, so it may be no better than yours. I also have a VHS copy of the KW1I slide show from one of the Dayton events from the 80s or early 90s that might interest to group. Come to think of it, Dale probably has a copy as well! 73, -Larry/NE1S Jim candela writes: Larry, Maybe your tape has is a better reproduction than the one I have of the SPAM video. VHS as I recall is 640 X 480 whereas what I posted was 320 X 240 resolution. If you got a decent copy, maybe somebody can convert that to a VCD or DVD for those that want better quality video? Anybody think about making a AM new video in 2006? Regards, Jim -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of ne1s Sent: Monday, February 27, 2006 11:44 AM To: Discussion of AM Radio Subject: [AMRadio] Re: 1986 AM Ham-radio Video I still have my VHS copy from 20 years ago, too. I most recently watched it with a friend (W1UJR) a couple of years ago. -Larry/NE1S Jim candela writes: Hi All, My son Paul just transferred the old SPAM (Society for the Preservation of Amplitude Modulation) VHS video tape to a digital AVI file. This was circulated to me by the late Floyd Dunlap, WA5TWF. The video was produced by Dave Ramser KG6AB and Norm Scott WB6TRQ. This video was very well done. I really enjoyed the interview with Mr. EF Johnson. My copy was on a 20 year old tape recorded on low speed so the quality is a bit lacking, and a high degree of video compression results in a noticeable lip-sync offset. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.1.0/269 - Release Date: 2/24/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.1.0/269 - Release Date: 2/24/2006 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: 6BG6 ad
The Elmac A-54H (my mobile XMTR) uses 6L6s in the modulator. -Larry/NE1S Jim candela writes: Hmmm, Well it seems like the ads claim is true, verified by Mahlon, K4OQ. In that case I reiterate, this is "one heck of a deal". Try pricing the 6L6GC from any source NOS or new, and compare. How many AM rigs use the 6L6 as modulators? Johnson Ranger (is this correct?) 1614 7027 How many others? Here are a couple more references about the 6L6 and its history, and descendants: http://listserv.tempe.gov/admin/WA.EXE?A2=ind9712&L=boatanchors&D=0&P=14006 "The first American television horizontal amplifier or "sweep" tube, the 6BG6G, came out in 1946., and was a repackaged 6L6". http://en.wikipedia.org/wiki/6L6 One of the largest post-WWII applications was in the basic design of television sweep power tubes, starting with the 6BG6 (1946), a modified 807. 6L6 From Wikipedia, the free encyclopedia Jump to: navigation, search Pair of 6L6GC tubes; (l) General Electric version from 1960s, (r) current manufacture from Svetlana Electron Devices, Russia Pair of 6L6GC tubes; (l) General Electric version from 1960s, (r) current manufacture from Svetlana Electron Devices, Russia 6L6 is the designator for a vacuum tube introduced by Radio Corporation of America RCA United States in July 1936. RCA obtained the design for the "kinkless tetrode" or Beam tetrode from British firm Marconi & Osram Valve (MOV) through a design share agreement, although RCA's own engineers were developing similar designs at that time. The 6L6 is a descendant of the "Harries Valve" developed by British engineer J. Owen Harries and marketed by the Hivac Co. Ltd. in 1935. Harries is believed to be the first engineer to discover the "critical distance" effect, which maximized the efficiency of a power tetrode by positioning its anode at a distance which is a specific multiple of the screen grid-cathode distance. This design also minimized interference of secondary emission electrons dislodged from the anode. EMI engineers Cabot Bull and Sidney Rodda improved the Harries design with a pair of beam plates, connected to the cathode, which directed the electron streams into two narrow areas and also acted like a suppressor grid to absorb some secondary electrons. The beam design was also undertaken to avoid the patents which the giant Philips firm held on power pentodes in Europe. Because this overall design eliminated the "tetrode kink" in the lower parts of the tetrode's voltage-current characteristic curves (which sometimes caused tetrode amplifiers to become unstable), MOV marketed this tube family under the sobriquet "KT", meaning "kinkless tetrode". Because MOV's engineers did not feel the kinkless tetrode could be successfully mass-produced, they licensed the design to RCA--which proved to be a poor business decision on MOV's part. RCA subsequently had enormous success with the 6L6. It replaced the use of power triodes in public-address amplifiers almost overnight. So many applications were found for the 6L6 that a complete list would be impossible to assemble. MOV introduced their version, KT66, a year later. RCA's first version had a metal-canister shell rather than glass--being one of the early octal base tubes, most of which were marketed as having metal shells (some radio users were nervous about being injured by glass from a broken tube). Later versions, including the 6L6G, 6L6GA, 6L6GB, 5881, 5932, and the final version 6L6GC had glass envelopes, which made radiation cooling of the anode easier. The original metal version was rated for 19 watts dissipation, while the 6L6GC is usually rated for 30 watts. The list of variations of the 6L6 design would fill a fat textbook. Early variations included transmitting tubes such as the 807 (1937) and the giant 813 (1938), the smaller 6V6 (1937), the many KT versions marketed in Europe, and a subsequent vast array of audio and RF power tubes. One of the largest post-WWII applications was in the basic design of television sweep power tubes, starting with the 6BG6 (1946), a modified 807. TV sweep tubes were not replaced by transistors in earnest, until the 1970s. Further testimony for this device's success would be even simpler: the 6L6GC version is still being manufactured and used, primarily in guitar amplifiers. Manufacture continues in Russia (2 factories), China (2 factories), Slovakia and Serbia. Thus, the 6L6 has enjoyed one of the longest active lifetimes of any electronic component; almost 70 years. -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.1.1/271 - Release Date: 2/28/2006 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailma
[AMRadio] Re: 51J3 or 75A3?
W5OMR/Geoff writes: The 170 (that I had) had a 'maximum' of 3kHz bandwidth.How narrow and mechanical it sounded. (blech!) I think with the sideband switch on "both" that 3KHz seletivity position actually means 6KHz, 2 means 4, etc. That said, they DO sound pretty nasty! 73, -Larry/NE1S
[AMRadio] Re: TV-7D/U
Hi Dale/group, I don't have a TV-7D/U, but I believe the "fuse" bulb is a once-common automotive bulb, and if you can get the number can probably be had at your local freindly NAPA store or equivalent. -Larry/NE1S Dale Smith writes: Hi Folks Does anyone have one of these tube testers?Just picked one up but the power cord has been cut,and the fuse and bulb for shorts are missing. I need a parts list or something the part numbers are fuse lamp#E103...Neon shorts lamp#E101 pilot lamp#E102,but I still don,t know the values.Also the line cord,does the plus go to the power switch and negative to the line adjust,any help would be great. thanks.dale/ka5who __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: use of scope to monitor output audio
I think it will only make a difference on those rigs (riceboxes) that have SWR protection, which will limit (clip) the peak output power when operating into a high SWR. -Larry/NE1S Brett gazdzinski writes: I have never noticed any difference in the sound, what gets to the other end will be lower in signal strength with some setups, not much difference with other setups like open wire feeders. Any watt meter will not be accurate I would think. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, March 22, 2006 7:12 AM To: AMRadio@mailman.qth.net Subject: [AMRadio] use of scope to monitor output audio 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? Alan __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: Modulator design needed
While other tubes may do better, I've had good luck using AB1 807s in VikingI/II/DX-100 class transmitters - they'll do 100% cleanly. -Larry/NE1S Gary Schafer writes: Just remember if you are going to use a tube phase inverter rather than a driver transformer the modulator tubes need to be run in AB1 and not AB2. You can't run any grid current without a driver transformer. This leaves out 807's as modulators as you can't get very much power out of them in AB1 but they are fine in AB2 as they are used in most rigs. Dx100 etc. 73 Gary K4FMX -Original Message- From: [EMAIL PROTECTED] [mailto:amradio- [EMAIL PROTECTED] On Behalf Of Peter Markavage Sent: Sunday, March 26, 2006 1:34 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] Modulator design needed 12BY7 drives the driver transformer which, in turn drives the EL-34's. Build a phase inverter, like many of the Hi-Fi amps that don't use a driver transformer to drive the EL-34's. Pete, wa2cwa On Sun, 26 Mar 2006 13:19:06 -0500 "Mike Sawyer" <[EMAIL PROTECTED]> writes: > Bob, > I suggest you look at the schematics again. The output of the > 5763 goes > no where near the modulator. I don't have the schematics in front > of me but > I have done some extensive work in the audio section. > Mod-U-Lator, > Mike(y) > W3SLK > - Original Message - > From: <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]>; "Discussion of AM Radio" > ; > "Discussion of AM Radio" > Sent: Sunday, March 26, 2006 12:59 PM > Subject: Re: [AMRadio] Modulator design needed > > > Mark, > > Take a look at a Heathkit Apache schematic, (TX-1), for ideas. > > There is NO driver transformer. The 5763 driver goes to the Mod > transformer > and the EL-34s feed it for audio. > > Bob - N0DGN > > -- Original message -- > From: "W1EOF" <[EMAIL PROTECTED]> > > > > I've been gifted a nice mod transformer so I can build a modulator > for my > > Johnson 6N2. I don't have a driver transformer so I'm looking for > a design > > which doesn't need one. I'm sure the schematics are out there, but > I keep > > finding ones with the driver transformer. Same with all my old > radio books > > that I've looked at so far. Can someone point me in the direction > of a > > good > > design that is online, or one that you can share with me via > email? > > Thanks! __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: Modulator design needed
Not in mine they don't, Gary, OM ;>) I'm talking fairly extensive mods here: (1) Change screen grid voltage to ~450V, preferably regulated. (plate V is about 550 - 600). Change control grid bias to ~ -50V for proper operating point (~35 - 40mA/tube quiescent). This allows up to 50V of audio on each grid (100V P-P) before going into grid current. (2) Replace adio driver transformer with resistance-coupled phase inverter. I've used the split-load circuit, as well as others, with good results. (3) Feedback from mod xfmr secondary to phase inverter input. Roll off highs in the feedback network so that phase shift don't getcha! (4) Increase 1st audio input resistor, beef up audio coupling & decoupling caps, replace .02 mfd accross mod xfmr secondary with 0.002, yada, yada... Works for me - I did it for my Viking I, and a friends Viking II. Able to modulate the things at 100% cleanly at full rated input. Can't argue with the results! 73, -Larry/NE1S Gary Schafer writes: The 807's in the Viking and DX-100 run in AB2. In AB1 you wont get more than around 45 to 50 watts of audio before they start drawing grid current. In AB2 they will produce 120 watts of audio. 73 Gary K4FMX -Original Message- From: ne1s [mailto:[EMAIL PROTECTED] Sent: Monday, March 27, 2006 1:06 PM To: [EMAIL PROTECTED]; Discussion of AM Radio Subject: Re: Modulator design needed While other tubes may do better, I've had good luck using AB1 807s in VikingI/II/DX-100 class transmitters - they'll do 100% cleanly. -Larry/NE1S Gary Schafer writes: > Just remember if you are going to use a tube phase inverter rather than a > driver transformer the modulator tubes need to be run in AB1 and not AB2. > You can't run any grid current without a driver transformer. > This leaves out 807's as modulators as you can't get very much power out of > them in AB1 but they are fine in AB2 as they are used in most rigs. Dx100 > etc. > > 73 > Gary K4FMX > > >> -Original Message- >> From: [EMAIL PROTECTED] [mailto:amradio- >> [EMAIL PROTECTED] On Behalf Of Peter Markavage >> Sent: Sunday, March 26, 2006 1:34 PM >> To: amradio@mailman.qth.net >> Subject: Re: [AMRadio] Modulator design needed >> >> 12BY7 drives the driver transformer which, in turn drives the EL-34's. >> >> Build a phase inverter, like many of the Hi-Fi amps that don't use a >> driver transformer to drive the EL-34's. >> >> Pete, wa2cwa >> >> On Sun, 26 Mar 2006 13:19:06 -0500 "Mike Sawyer" <[EMAIL PROTECTED]> >> writes: >> > Bob, >> > I suggest you look at the schematics again. The output of the >> > 5763 goes >> > no where near the modulator. I don't have the schematics in front >> > of me but >> > I have done some extensive work in the audio section. >> > Mod-U-Lator, >> > Mike(y) >> > W3SLK >> > - Original Message - >> > From: <[EMAIL PROTECTED]> >> > To: <[EMAIL PROTECTED]>; "Discussion of AM Radio" >> > ; >> > "Discussion of AM Radio" >> > Sent: Sunday, March 26, 2006 12:59 PM >> > Subject: Re: [AMRadio] Modulator design needed >> > >> > >> > Mark, >> > >> > Take a look at a Heathkit Apache schematic, (TX-1), for ideas. >> > >> > There is NO driver transformer. The 5763 driver goes to the Mod >> > transformer >> > and the EL-34s feed it for audio. >> > >> > Bob - N0DGN >> > >> > -- Original message -- >> > From: "W1EOF" <[EMAIL PROTECTED]> >> > > >> > > I've been gifted a nice mod transformer so I can build a modulator >> > for my >> > > Johnson 6N2. I don't have a driver transformer so I'm looking for >> > a design >> > > which doesn't need one. I'm sure the schematics are out there, but >> > I keep >> > > finding ones with the driver transformer. Same with all my old >> > radio books >> > > that I've looked at so far. Can someone point me in the direction >> > of a >> > > good >> > > design that is online, or one that you can share with me via >> > email? >> > > Thanks! >> __ >> AMRadio mailing list >> Home: http://mailman.qth.net/mailman/listinfo/amradio >> Help: http://mailman.qth.net/mmfaq.html >> Post: mailto:AMRadio@mailman.qth.net >> AMfone Website: http://www.amfone.net >> AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] Re: Modulator design needed
Never measured the screen current, Dennis, it may well be exceeding the dissipating ratings. That said, I've never had to replace any of the 807's, they're still cranking (in one case after ~10 years of intemittant use), and this is not too much different from where Fender used to run 6L6GC screens in some of their guitar amps. (the 6L6 family is nearly identical electrically to the 807/1625). And in the transmitters I've done this to there's no screen or plate volts on the 807s during standby. 73, -Larry/NE1S [EMAIL PROTECTED] writes: (1) Change screen grid voltage to ~450V, Wow, that's pretty hot for an 807. What kind of screen dissapation numbers are you seeing with this?
[AMRadio] Re: Modulator design needed
Hi Geoff, As a matter of fact, I try to par particular attention to this, and typically only leave the info i consider pertinent (sp?)from the previous message in the reply. It is possible that I screwed up on this occaision (if so, please accept my apologies), or that what I think is pertinent & necassary (so that the contest of the reply is understood) dissagrees with your assessment. (Since you included none of my original posting, I can't tell ;>)) 73, -Larry/NE1S W5OMR/Geoff writes: Is it really that hard, Larry, to delete all of the unnecesary message?
[AMRadio] Re: W1AW vs. K1MAN
W5OMR/Geoff writes: Jerry/W5KLV used to be (as recent as a year, or two ago?) the "OBS" for the 5th Region/section of the National Traffic System. I had always thought "OBS" stood for "Old Buzzard Station." :>) -Larry/NE1S
[AMRadio] Re: Triode connecting 803's for a Modulator
Elaborating on Don's comment, the reason this is done with the triode-connected 807 is that if the control & screen grids were simply tied together, the control grids would be exceeding their maximum dissapation before the screens could be driven hard enough to provide reasonable output. We don't want to vaporize the control grids now, do we :>) I suspect this would hold true for other tetrodes & pentodes in a triode connection. I've used 6146s as modulators in the triode connection on a couple of occaisions. I feed audio to the screen grids only and just bias the control grid with a DC voltage to set it at the proper operating point. At lower plate voltages (say, <600V or so), the control grids can be tied directly to ground. At higher plate voltage, a few volts negative wrt cathode is all it takes. Screens are at DC ground in either case. Perhaps try something similar with the 803s? 73, -Larry/NE1S Donald Chester writes: 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.
[AMRadio] Re: Ranger II Problem ? Need Help..
Once I had a problem with my Ranger I, which could be what you are experiecing (maybe, maybe not...) The 6CL6 driver was taking off and oscillating with no signal applied to it's grid. This created a nasty hum in the reciever. Setting the driver plate tank capacitor slightly off-resonance (I think the control labeled "buffer" on the panel) made it go away. It was occurring on 160M only. 73 & GL, -Larry/NE1S Mark McDougal writes: I have a Ranger II that's developed a problem and I really don't know where to start looking. The problem is a very loud hum, seems like 60 Hz, heard in my receiver, that comes from the ranger.. The transmitter tunes up fine, and modulation is O.K. It isn't there when the transmitter is zeroed into the receiver, just when I remove the zero.. Completely wipes out the receiver..
[AMRadio] Re: AEA Moscow MufflerWoodpeckerBlankerWB-1
Yeah, Todd, now that you're back on 40 & 75M, it's time to put up a wire for 160M! Hey Phil, come up and say hello to us on the Gray Hair Net sometime. It's been quite a while... 73,-Larry/NE1S Phil Galasso writes: Welcome back, Todd! I don't normally work 75 meters, but come on down to 160. I usually hang out on 1885, often early in the evening this time of the year, as I can evade the static by getting on early...yet there is plenty of skywave from 1, 2, and 3-land! Hell, Ken, why don't you come on down as well? Phil K2PG
[AMRadio] Re: Amplifier with input drive to screen grid
It sounds like they were connecting the 813s as zero-bias triodes, more often done in modulator service. Don't know why they'd do this instead of run them GG in this application, though, unless there was an appreciable difference in gain. Maybe the guy just wanted to experiment with something "different." I don't see how the grid current meter connected as you described would register any grid current at all, 'cuz I can't see that the control grid would go positive wrt the cathode in that configuration. Does it move off the peg at all?? 73, -Larry/NE1S Bill Fondren writes: I recently traded for a linear that has a strange input circuit, at least to me. The amp is built in a 18 " Bud rack mount cabinet weighting about 150 lbs. To heavy for 1 person to handle so I deceided to split the RF deck from the power supply and put it in a taller cabinet along with the exciter. No info was with the unit. I have used it a couple of times and it works fine . It uses a pair of 813's in parallel. I started to draw out the circuit finding that the drive goes to a tuned circuit and then to the sceen grids of the 813's. The control grids are connected together and go to a 10K resistor, the grid current meter and then to grd. No connection to the drive circuit at all other than the interelectrode cap. I guess. The plate circuit seems to be normal. Just wondering if any one has seen something like this before. Bill K5PML
[AMRadio] 20M AM Activity
I'd like to stir up some activity on 14.286 AM. There used to be quite an active group up there with W6HQI(SK), W8VYZ, WA4KCY, W6HDU, and others. I'd join them from time-to-time back in the latter 80's and early 90's. I talked to W8VYZ last weekend on 40M, and he said he still gets up there, but I've not heard him when I've looked in recent weeks. I called a CQ w(ith one of my Viking Is) on the above-mentioned frequency last Wed. nite, and a pleasent QSO ensued with a ham that I had never before met, although he lives all of 15 miles from me! Then last nite I called CQ (using the 30s homebrew rig - PP 812As modulated by 805s - 1st time this rig has been on 20M!) and this resulted in 3 consecutive solid QSOs - N4VIC/mobile in GA, N4OYT (also in GA, but not moile), and KJ0L (IA). None of these guys, including last week's qso, were regular AM ops, but they put their rigs on AM for the occaision. So, I guess all of this is just meant to encourage folks to check out 14.286 and call an AM CQ now and then - you get to meet new folks other than the (usually local) group of regulars that are on the lower bands. I'll be spending more time up there, I know. Look for me between 8-10PM, especially Monday evenings. 73, -Larry/NE1S
[AMRadio] Re: How the reply button works
My votes: 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. -Larry/NE1S
[AMRadio] Re: DC Load
[EMAIL PROTECTED] writes: Somewhar in my files, I have a simular circuit...If u like, I'll rummage through and see what I can find. I think it utilized a 100th as the variable resistor klc Back when I started my working life about 25 years ago, I was a process engineer for an electron-beam aluminum evaporation process. The DC power supplies were adjustable & regulated, and supplied on the order of 15KV at a few amps. They used a 3CW2A7 as the linear series pass device. 73, -Larry/NE1S
[AMRadio] Re: DC Load
Don Merz writes: -(SNIP)- I went through my files and found a photocopy of a very similar circuit using 6BG6 tubes in parallel. But I guess I'm not sure what tubes this one was intended to use--likely something that is expensive these days. I'd like to put this thing to it's intended use. But I don't want to put $100 worth of tubes into it. What are the options? Any ideas appreciated. 73, Don Merz, N3RHT How about a single 833A? Broadcast pulls should be available at not too much expense, triode, & same fil. voltage. Sounds like the filament transformer should be capable of 7A minimum. Check, because the 833A requires 10A, IIRC. Of course the 833A socket (if you can call it that) is hard to come by, but it wouldn't be too difficult to rig something. I'm afraid finding any tube (838, 203, 211, 845) that fit's you socket would be expensive, as you say. Just had another thought, though. Seems to me there are new 845s being made in China (or at least there were in the not-too-distant past). Don't know what they get for them, or if they're still on the market. 73, -Larry/NE1S
[AMRadio] Re: Ranger VFO
I've had good luck with steel wire - I used some extra copperweld for mine - it's appropriately stiff & springy to sub for the original. GL, -Larry/NE1S - Original Message - From: "Rick Brashear" <[EMAIL PROTECTED]> I have a dandy problem that I hope someone can help with. I am in need of the little spring clips that go on the bottom of the VFO tuning pegs in a Ranger transmitter. I have the pegs, but the clips are gone. Has anyone come up with a good solution to this? What else can I use? I thought about just soldering a small piece of heavy wire across the variable capacitors on the VFO and slipping the peg's slot over it. Any ideas? Rick/K5IZ __ 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: Ranger... good news, bad news
Jack Schmidling writes: I tried the accessory plug mod as suggested, removing 2/6 and putting a meter across 2/4 and it works but the power is less than useful. It less than 5 watts and would only modulate about 25%. Did I do something wrong? It sounds like you did it right - there's not much to screw up. Maybe the Ranger has a problem. I get about 12W out from that connection. My Ranger power supply is not stock, but the voltages are pretty close. However, 15W is what I hear reported from others who have done this. It helps to reduce the grid drive a bit in the low power mode - adjust the drive pot for maximum RF out of the Ranger - but it won't make the difference between 5W and 12W out. And you should have absolutely no problem modulating to 100% positive and beyond if your audio is phased correctly and the modulator is working correctly; especially using the low power mod where you should have plenty of audio power to spare. How much RF carrier do you get out of the Ranger when operating normally, and are you able to modulate 100% then? 73, -Larry/NE1S __ 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: Ranger... good news, bad news
Jack & list, see my answers & comments below. -Larry/NE1S Jack Schmidling writes: We speak of peak envelop POWER but a scope is actually displaying peak voltage. How do we relate this to 4 times carrier on a scope? The RF voltage on modulation peaks is exactly twice that of the unmodulated carrier, for 100% positive modulation. Since the RF load impedance is fixed (and can be considered 100% resistive for the sake of argument, and will be close to that practically anyway) when voltage doubles, current doubles too, so hence the positive peaks indicate 4X the power. (P = IV = V**2/R, so if the voltage doubles (as does the current) the power will quadruple). > I still do not understand. The final is tuned with a tank capacitor and a loading cap. On my amp, the optimal positions of these knobs only change with the frequency is changed. Changing the input level does not effect this tuning in any way that I can see. Your amp then doesn't behave like any linear amplifier I've ever played with. The tune and load settings for maximum output have always depended on the input drive level for me, at any fixed frequency. There is a theoretical argument why this must be, as well, but I'm having a brain cramp on that at present (I USED to know, honest :>)) -SNIP- However, today I changed the rf pickup from a loop on top of the tuner to a wire just running off away from the rig. Bottom line is, that it now looks like 100% modulation. Good. Odd, but good. __ 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: Ranger... good news, bad news
Jack Schmidling writes: Gary Schafer wrote: So unless you have some higher gain tubes in the amp 12 to 15 watts drive will not be enough drive. -SNIP- I have contended all along that it takes about 20w drive. Everything seems to work well including 100% mod when I drive with 20w. Only >problem being that the tubes redden. The low-voltage B+ modification may not be practical for you, Jack. Any class AB2 grounded-grid linear I've ever played with (and I've designed and built two) had a power gain between 10 - 15. Someone said the power gain of you amp was only around 6. So after reducing the Ranger power to 12W and feeding the amp, you'll only be getting ~70W carrier out, not quite double what the unmodified Ranger puts out (~40W). Hardly worthwhile. As a point of interest, I am using 6L6's in the modulator but assume they just won't last as long and not effect the amount of modulation. Is this > a good assumption? Kinda depends. From memory the original metal 6L6 only had a maximum plate voltage rating of 350V, so voltage breakdown at the socket may be a problem. The maximum plate voltage of the 6L6GC was 400 or 450V. I can't remember if there was a difference in the maximum plate dissipation. Anecdotally, I am running 5881s in my Ranger that gets used reqularly, and they've been in there at least 10 years. They may be a bit soft by now but still give me nice sharp peaks in excess of 100%. As long as the tubes survive, though, they should be equivalent to the 1614 electrically, and thus in terms of their ability to modulate. 73/GL, -Larry/NE1S __ 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: 10 & 15 Meter Gathering
Mark K3MSB writes: To facilitate activity on 10 and 15, what y'all think of establishing a weekly activity time? Say 3 PM EDT Saturdays and Sundays on 10 and 15 (29.0 and 21.425) ? Great idea, Mark. I'll make it a point to listen and/or make some noise there and then (but not this Sunday - 1929 AWA CW QSO party instead). -Larry/NE1S __ 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: RF Amp
Brian - is that the rig your were using on the Collins AM nite last evening? You were pounding into Maine! (Almost gave you a call, but I'd already "had my turn" with W0YVA.) 73, -Larry/NE1S A.R.S. - W5AMI writes: You can also get a chance to hear me on a 450TL rig, as that's my primary transmitter. __ 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: Pw Supply
Hi Jack,
See comments/answers below.
73/GL,
-Larry/NE1S
Jack Schmidling writes:
MFJ has a 900v one for about $100. Is there any reason why I can not use
two of these and tie one side of the secondaries together and call that
the center tap and have an 1800v ct transformer/s?
Jim Candela has already given the correct answer ("no"), and why.
I am using 866's so I must have a center tap.
Not necessarily! Use 4 866's in a full-wave bridge. But this will require a
minimum of 3 filament transformers for the 866's.
Second question is:
Mine has the HV going to the choke and then to two 4 mf 3kv caps in
parallel. Is it not more conventional to put a cap on each side of the
choke or two chokes for a choke input filter?
Choke-input and capacitor-input filters have very different voltage outputs,
not to mention dynamic voltage-regulation. Also, mercury-vapor rectifiers
get VERY UNHAPPY looking into capacitor-input filters. If you use MV
rectifiers, you MUST use a choke-input filter. With a choke input filter,
you need to be cognizant of the minimum current being sourced from the
supply and the required critical (minimumum) inductance of the choke. Do you
have a period (1930's - 1950's) handbook you can review?
What would I gain or lose by moving one of the caps to the HV side?
If you use cap-input with MV rectifiers, you'll at least lose the
rectifiers! Otherwise, you'll gain unloaded output voltage, at the expense
of poorer dynamic voltage regulation, & put more stress on *(from higher
peak currents in) the (SS diode or vacuum) rectifiers and plate transformer.
I thought this has mostly already been covered in this thread?
__
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: Screen Modulated 813
Bry Carling writes: DX-60 followed by an 813 RF linear or SB200. Versus: 813 screen modulated final using the same method that sets the quiescent carrier level at about 10% of peak signal. Which would be more efficient? It's my understanding that from a 1st order analysis (ignoring subtleties like what plate voltage they are being run at, any differences in efficiencies between the tube types, output network design, etc, etc.), the plate efficiencies would theoretically be the same between a screen-modulated stage and a class AB linear amplifier stage amplifying an AM signal, since they are both essentially "efficiency modulation" techniques. 73.0000, -Larry/NE1S __ 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: Screen Modulated 813
david knepper writes: Zirconium getters best at about 1000 degrees C, this why large metal anode transmitting tubes like the 4-400A, 4-1000A, and 3-500 must be operated with a dull red to red anode color. It's also why it's used to "encrust" tweezers ;>) -Larry/NE1S __ 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: Screen Modulated 813
Bry Carling writes: Lary - I was talking about the kind of set-up with the 6DE7 that produces a SMALL carrier of say 6 or 8 watts and then does 90 watts p.e.p. on the voice peaks. Right - that is the question I addressed. I may be nuts, but my empirical sense tells me that is far more impressive sounding in the receiver n the other end than the signal from the typical "novice rig" that runs 75 watts carrier input with Heising mod. OR even a plate modulated class C rig with 22.5 watts carrier input and 90 watts p.e.p. I think by "impressive" you mean the ratio of power in the sidebands to unmodulated carrier power - if so, I'd agree. The power is turned DOWN during the inefficient phase of the transmission in other words. We need to be careful here, because this created a misunderstanding about a year ago. With efficiency modulation (be it a linear amplifier stage, or screen suppressor, or control-grid modulated amplifier) PLATE EFFICIENCY (RF power output/DC plate power input) is lowest when the instantateous output is lowest. Therefore, the lower the output of the unmodulated carrier, the lower the PLATE EFFICIENCY. If we think of efficiency in terms of power in the sidebands/total power consumed (integrated over time), your statement is correct. WIth less and less quiescent signal the transmitter appraoches the efficiency level of a DSB rig. Yes - in the limit, as the carrier level is reduced to zero, that's exactly what your left with: DSB w/o carrier. But the above comments on efficency still hold - plate efficiency in this case will be zero when no modulation is present, because there is no RF output, with finite DC plate power consumed. But, integrated over time, I believe less power will be consumed to convey the intelligence, so in this sense, "efficiency" is better. 73, -Larry/NE1S __ 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: SPAM
D. Chester writes: When Floyd unexpectedly went SK, Hoisy W4CJL who was founder of SPAM agreed to let a guy in California take over. That would have been Norm, WB6TRQ, IIRC. -Larry/NE1S (who was the Maine state SPAM director, way back in the 80s) __ 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 To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] Re: SPAM
Bob Peters writes: Larry What was your call then??? You look familiar... Bob W1PE ex K1JNN Can't remember if I had the present callsign then or if I was still KA1KUH. (I've been NE1S since 1986). -Larry __ 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 To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] Re: WTB: National R-175 plate choke or equiv
Jim Wilhite writes: Mark, you might consider using something else for the choke. The R 175 is marginal on 160 meters. If you use one, then add a series choke of about 1.5 micro henries to tame it. Jim, I think you meant 1.5 millihenries, correct? -Larry/NE1S __ 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 To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] A Phoenix rises from the ashes...
Forwarded from another list: "Hosstrader Hamfesters take note, here is the successor The NEW ENGLAND AMATEUR RADIO FESTIVAL (NEAR-Fest) will hold its' Spring 2007 get-together and flea market on Friday May 4th and Saturday May 5th at the Deerfield Fairgrounds located on Highway 43 in the Town of Deerfield, New Hampshire USA. http://near-fest.com Be there! Aloha. 73, Michael, W1RC" This is great news for a couple of reasons: (1) Here in New England, Hosstraders was the largest & coolest* of all the hamfests, held once in the spring and once in the fall. We were all very bummed, to say the least, when the group that organized the fester announced their "retirement." Now a new fest is filling the slot. (2) Doubly cool is the fact that it will be held at the Deerfield NH fairgrounds, where Hosstraders was held back in its heydey, and where I attended my first hamfest back in 1983. Just about anyone who attended Hosstraders during the Deerfield days regards this site as the best venue. "Holy Ground," in fact. I'm a happy camper. *very high quality/crap** ratio as far as wares offered, and big AMer turnout/party. **quality = tube radio equipment; crap = ceramic lawn frogs (for example) 73, -Larry/NE1S __ 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.
[AMRadio] Re: ARRL changes: League dumps threat to AM
Brett gazdzinski writes: I would move up there, you got free health care and so on, but its to cold for motorcycles! C'mon, Brett. I know you're too principled a guy to use the force of the state to confiscate property from others in order to finance your own health care ;>) Heard you calling CQ on 7290 yesterday, but was in the middle of lifting weights, so didn't answer. There were a bunch of 2's and 3's calling CQ, sometimes on top of one another, but all were apparently in each other's skip zone. I was hearing them quite well up here in Maine, though. 73, -Larry/NE1S __ 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.
[AMRadio] Re: 4-65's
Geoff/W5OMR writes: Does anyone have any 4-65's? I think that'd be a neat little ~100w rig to build up.. a single 4-65 tetrode, modulated by a pair. Sounds like a neat combination. You oughta be able to get about 150W carrier out of one, run less conservatively (not that anyone will hear the difference, of course). Someday I am going to build a rig with a pair of 'em modulated by 811s, when I get a round tuit. Already have the HV PS/modulator deck built, just have to do up the RF deck, which will also contain the VFO (a T-195 PTO I've been saving for this project), and RF and AF driver circuits. I hope to run the pair at 500W input (2500V @ 200 mA), or close to it, depending on the plate efficiency I'm able to achieve. -SNIP- 6.3v @ 3.5a? Got those transformers, too. Actually, they want 6.0V, so drop the voltage to the primary or run resistors in the primary or secondary circuits of the fil xfmr. One trick is to use appropriate lengths of undersized wire to the filaments (whatever length is necessary to drop the filament voltage at the socket to 6.0 V). GL, -Larry/NE1S __ 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.
[AMRadio] Re: OT Guitar Amps
Ed Hopton writes: The Dead did have their moments, and Garcia sometimes came up with some pretty cool stuff. Can't fault a guy who plays pedal steel! 73, Ed N3CMI Most of you probably already know this, but IIRC Garcia played the pedal steel in C, S, N, & Y's "Teach Your Children." -Larry/NE1S __ 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.
[AMRadio] Parasitic Suppressors (or lack thereof) in the Olden Days
Olden Days being pre-WWII, that is. I've noticed most (if not all) if the PP-triode RF PAs of that period don't show the use of any parasitic suppressors in the grid or plate leads. Also a deck I have (exact vintage unknown) using PP triodes doesn't include them. How did they get away with this? I've never put power to the above-mentioned deck, but have another one where I tried to follow the same practice (I just used copper strap for the plate leads) and I appear to have an intermittent parasitic, so will be incorporating some suppressors in the plate leads. -Larry/NE1S __ 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.
[AMRadio] Re: Spy radio
kenw2dtc writes: The reasons we are not underdeveloped: Education? Inititive? Competition? Self assurance? Taking responsibility? Work ethic? A government that respects individual freedom (relative to the underdeveloped countries, that is. Room for improvement, of course). -Larry/NE1S __ 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.
[AMRadio] Re: WAS:Spy radio - Swapmeet and Auction Ethics
My view: there is nothing morally wrong with making a profit on amateur radio gear or any other legal goods. If someone doesn't like the price, he/she shouldn't buy; no one is holding a gun to their head telling them they have to do business. There is also nothing wrong with giving someone a good deal, or a gift. I think most of us have been grateful recipients of such kindness, and it's nice to pass it along from time to time. -Larry/NE1S __ 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.
[AMRadio] Re: Connectors
[EMAIL PROTECTED] writes: Hi Rick, On most of the newer style connectors, the colored collars can be easily removed by cutting along the length with a pair of dikes. The result is a bare lug to which the wire may be crimped or soldered. 73, John, W4AWM Or, simply heat up the lug with your soldering iron, and the offending plastic collar slides right off. It doesn't take much heat. -Larry/NE1S __ 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.
[AMRadio] Re: 18.150 ?
VJB writes: I would like to cut a dipole for 18.150 and see what kind of AM activity we could stir up. The band is lightly loaded most of the time, so there's room for the occasional chat. Anyone else thought of that ? A few years back I tried loading up the PDM rig on 18 MHz. It's been on 15M and 20M successfully, and the grid and plate tank components are continuously variable, so why not? Well, it didn't like it one bit. I suspected a resonance near 18MHz in the plate choke, but didn't verify it. Fortunately the only damage was melted plastic insulation on the HV lead to the plate choke. But I have other rigs that I can try there. -Larry/NE1S __ 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.
[AMRadio] Re: of backward tilt
VJB writes: The best prospect among the sockets sort of started to go in, then, yes, I heard the sickening sound of vacuum reaching the outside world. Sucked big time. Quite literally ;>( The seal broke. I think it's held onto the glass with mucilage anyway, but that was that on that. Never lit it up, obviously. The other one is good. The broken tube might still prove to have some useful life in slimetron service :>) 73, -Larry/NE1S __ 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.
[AMRadio] 500 Kc (was Re: 450T amp)
My friend Bob Raide, W2ZM (aka cueball!), has one of the experimental licenses, and a station running up there. He had an article describing his transmitter in the most recent (April) AWA Journal. Also Conard (not misspelled!) WS4S, is another. -Larry/NE1S __ 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.
[AMRadio] Re: 500 Kc (was Re: 450T amp)
FB Dale, you're obviously more knowledgable about this than I am. I didn't realize there were different experimental applications for different frequencies in the vicinity that I was generically referring to as "500 Kc." I had also forgottten you were playing about down there! 73, -'1S Radio Station KW1I writes: Larry, I think Bob is on a new experimental application for another 600m segment. He is not one of the stations in the 505-510 kHz experimental operation. __ 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.
[AMRadio] Re: 500 Kc (Old Gear)
[EMAIL PROTECTED] writes: I have a weakness for the Westinghouse gear myself Terry, W2PFY runs a Westinghouse SW broadcast trnsmitter. We kid him about being an "appliance operator." :>) -Larry/NE1S __ 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.
[AMRadio] Re: 500 Kc (was Re: 450T amp)
Bry Carling writes: Why the heck don't they give hams 455 kHz as a CW channel since no one is using it any more? Or even as an AM CHANNEL?!!! Now THERE is a cool idea! You could easily detune the old tube AM broadcast band receivers to use them on that frequency! Pad those caps down from 530 kc. to 455 kc. An idea whose time has COME! Can't be done this way if the BCB receiver IF is 455 Kc, as it commonly is. In this case the LO would have to be running at 0 Kc! The way to do it would be to disable & bypass the front-end and couple the antenna directly to the 1st IF stage. As someone else had mentioned, problems would be likely with the 455Kc signal bleeding into the 455 Kc IF stages of other radios not intended to receive it. -Larry/NE1S __ 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.
[AMRadio] Radio Resuce Mission needed this weekend in Southern NJ
Passing this along from a recent add at QTH.com. After this weekend it'll be no more (John Dilks, this is right in your hometown! I'll also bet it's not too far from Brett): "NEW JERSEY ESTATE C L E A R O U T It is all going out. Either to the dumpster or to you guys. HAS TO HAPPEN THIS WEEKEND! All the brand radios and tranceivers etc are gone what remains are about FOUR THOUSAND TUBES (or so) Lots new and boxed. CRYSTAL radio Parts MOUSER!!! LOTS NEW IN BAGS. Decades of my fathers parts, teardowns, etc wooden boxes upon boxes of them. Drawers of METERS Many Homebuilt Rigs. LITERATURE some back to the twenties. YOU SEE***This all has to go***we have the house S O L D and it goes Price is not my concern If IF you want a tube, it is HERE<> Buy them ALL go into business. MapQuest the address 302 BUERGER STREET EGG HARBOR CITY NJ 08215 South Jersey easy to get to. PLEASE dont make me dump his stuff like this GOD it makes me sick to think of doing it. If you are HAMFEST dealer or builder PLEASE COME SATURDAY COMING UP BRING YOUR PICKUP P L E A S E K2QQF needs a better end for his goodies PLEASE HELP" All I know about this is what's in the above paragraph. Hope this stuff can all find good homes... -Larry/NE1S __ 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] Re: More on the Radio Rescue Mission needed this weekend in Southern NJ
John Dilks K2TQN writes: This location has been cherry picked . He sold the entire estate on ebay 6 months ago. I guess this is what's left and doesn't want to carry it out of the cellar by himself. Wear old clothes, as the cellar used to be very dusty with saw dust. The tubes there are/were mine, the father borrowed them from me. It is a long story. In my opinion the son is a greedy person and wanted me to sell his fathers estate so the son could have the money, while his father was still alive. His father was my friend, the son is not. I stayed out of it. Some things are not worth getting into. I'm sure you will find some parts still there, but no big treasurers. Ahh, the story behind the story! Thanks, John! I'll be able to sleep better knowing that a bunch of old radios and other cool artifacts won't be meeting an untimely end if I don't make an unscheduled weekend trip from ME to NJ and back! -Larry/NE1S __ 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] Re: WTB: AM IRON in the North Carolina area
Geoff/W5OMR writes: -SNIP- Grab a good ol' Johnson Viking II. They're floating around pretty much everywhere, mostly with VFO. A pair of 6146's, modulated by a pair of 807's... sits on the desktop, but it and a receiver will eat up most of the desktop. They're sometimes referred to as 'gray anvils' ;-) The most solid 100w high-level plate modulated rig, in my opinion. -- 73 = Best Regards, -Geoff/W5OMR (owner of 2 Viking II's.) Also, the Viking I is just as solid - same rig except has 4D32 final and no clamp tube, and cabinet is easier to deal with, it being a standard 19" "rack" type. -Larry/NE1S (owner of 2 Viking Is) __ 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] Re: WTB: AM IRON in the North Carolina area
Geoff/W5OMR writes: Maybe it's just personal opinion, but I've seen a couple of Viking I's, and I don't know that I'd ever mount one of those in an open-rack, as opposed to it's standard rack cabinet. The front panel, to me, seems rather 'flimsey' to support the weight of the power supply transformers and chokes, as far back as they are. The bottom (*I* think) needs to be supported, if it's to be rack-mounted in an open rack. Agreed - If you were to try to suspend the thing in a rack (as opposed to the standard cabinet where it's supported on the bottom) you would -at least- need to add side supports. Not just personal opinion, it's a fact (Jack!). Myself, I do prefer the rack-style cabinet a bit to the "integrated" style cabinet of the Viking II, for aesthetics and also in terms of gaining access to those parts of the radio directly behind the panel. But I think the Viking II style is better ventilated. Both great radios, though. -Larry/NE1S __ 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] Re: Average OP Age was BA Tr FS
Geoff/W5OMR writes: "What is the current through a 1k ohm resister if 1v is applied across it? A) 250 Amps B) 117VAC C) 47 ohms D) 100mA E) None of the above ;>) 73, -Larry/NE1S __ 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] Re: Boatanchor Transmitter FS in Salem, OR
Geoff/W5OMR writes: Gotta hand it to Jon/AD5HR... he's only been a ham for about 6 yeas... and he's building rigs. He's talking on a homebrew rig, running a pair of 807's modulated by a home-brewed modulator, running a pair of 807's, and the modulator is driven by his homebrew speech-amp. That rig, while desktop. probably weighs in at around 1.5 lbs per watt ;-) Sounds like Jon knows how to have fun! My bet is the hobby will hold his interest a lot longer than for the kilobuck ricebox or shack-on-a-belt types. I made my first contact as a Johnny Novice back in '83 with a transmitter I built myself - a 6AU6 driving a 6146 (OK, so I used a Knight VFO with it). Been hamming non-stop ever since, can't ever see giving it a rest. -Larry/NE1S ...who is 50, but was much younger 25 years ago! __ 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] Re: KWS-1 on AM
Phil Lamarche writes: I had a pair of KWS-1's, 75A4's while on Drift Station Alpha at the North Pole in 1958. Operated 24/7 for 11 months until the ice broke up and the two pairs are now 8000 ft below on the ocean floor. Someday they will show up on Eb***y. 73, -Larry/NE1S __ 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] Re: Average Age etc..
Geoff/W5OMR writes: Because When Inductive Reactance (X(l)) equals Capacitive Reactance (X(c)) you get Resonance! At least in triodes. Pentodes need some extra work, due to screen voltages/current. As far as I know, the condition of resonance: XsubL = XsubC ; holds for the LC resonant circuit, regardless of the active element it may be connected to, be it a pentode, tride, bipolar transistor, FET, tunnel diode, or whatever. Of course when the LC is connected to other "stuff," the parasitic reactances of the whole mess need to be considered and will contribute to the "total" XsubL and XsubC which determines the resonant point. That brings up a question... (and I'm asking because I just don't know pentodes/tetrodes) should the screen circuit be resonant at the operating frequency, as well? If we are considering a pentode/tetrode amplifier, the screen should be grounded for RF (i.e., well-bypassed at the operating frequency). Exceptions are certain oscillator circuits (modified Pierce, for example) where the screen is actually used as the plate of the triode formed by the cathode - control grid - screen grid, or when the screen may be used for signal injection in a mixer circuit. 73, -Larry/NE1S __ 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] Re: age poll
A.R.S. - WA5AM writes: I think your time estimation on the "old buzzard" transmissions of PYT are very close Kent. Bob always had "content" in his long dissertations, and I never seemed to mind waiting for him to finish. Actually, he could talk about almost anything. His knowledge spanned many subjects, all of which he made interesting. I sure do miss the old buzzard... Me too, but unfortunately I only got to talk to him during the sunspot peaks, on 10M. Also Mo - what was his call? K5AD, or similar? -Larry/NE1S __ 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] Re: age poll
A.R.S. - WA5AM writes: Do you happen to remember what rig he used on 10 Larry? Was it a Viking II? Brian, I'm not sure if you're referring to Ozona Bob or Mo, but in either case, no, sorry, I don't recall the rig (s0. Makes me wish my logging discipline was better than it is. 73, -Larry/NE1S __ 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] Re: age pole - JKO
Jim Candela writes: Later upgraded to a Lear T30 (6L6 mod by P-P 6l6) for 160m, a Viking I with 813 mod by P-P 8417's, and a Lafayette HE-30 receiver. That's some Viking I, Jim! Outboard power supply and/or modulator? What were you running for plate voltage on the 813? -Larry/NE1S __ 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] Re: would like to build a little homebrew project
Jason Buchanan writes: I'm wanting to build a little homebrew project and build bigger ones based on what I learn from the smaller project. Just wondering if anyone could point me in the right direction for building a nice little AM transmitter, preferably for use on 160 meters... Tube, or solid state? If tube, there are many possibilities in the older handbooks (left coast as well as ARRL). As a first project, I'd start with a low to medium power class transmitter. If you have trouble finding affordable mod iron, a screen-modulated sweep-tube into a linear amp will put you at roughly 150-200W carrier output (I frequently use such a set-up on 160M). If solid state, check out www.classeradio.com/ for some nice designs that'll make you sound like a million bucks. When you get 'er done, join us on the Gray Hair Net on 1.945MHz on Tuesday evenings at 8:30 EDT, or 8:00 EST, assuming you are within hollering distance of the northeastern US (I assume you are because of the "1" callsign, but ya never can tell these days ;>)) 73/GL, -Larry/NE1S __ 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] Re: would like to build a little homebrew project
Jason Buchanan writes: hi - thanks for the info. I live in Boxboro, MA which is pretty close to QIX's QTH (i'm 1 mile as the crow flies from the Boxboro ham fest)... Cool - I've been going to Boxboro for years. Got to try to catch up with him on air sometime and maybe swing by his house and check out all that great stuff he has. I have heard him on 160 in the past with that monster signal but at the time I was super busy and didn't have the time to think about building anything... Steve's a great guy, and one of a select few folks I've met to whom I bestow the title "genius" without reservation. but now that I have a full wave loop I can work that far up into 160m (my old dipole cut for CW had terrible SWR at 1945KC). Shucks, maybe I can take a ride up your way if you have time. Sure thing! I'm in Gray, ME and good in QRZ. Typically have Fridays - Sundays free (slowly working my way to retirement). Always keeping busy, but with a bit of warning I will MAKE time. I have some Drake 4 line gear and an icom 707 that can run AM so will try to listen for you tonight on the gray hair net. Maybe even try to check in but with the Drake's controlled carrier setup it won't be the same Use what you've got! We WILL hear you. If you ever build a big rig, you can use the Drake as a stable & reliable signal source. 73, -Larry/NE1S __ 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] Re: I've decided (retry)
Geoff/W5OMR writes: I'm soliciting ideas on grid inputs on a 4-125. Thoughts? Many ways to do this, Geoff, as I'm sure you know. What worked out well for me on the FR deck in the big PDM rig (pair of 7527A's in parallel) was to load the grid with ~2500 ohms non-reactive (a bunch of non-X 7W resistors in series) and match it from a 50 ohm source with a T network - two series variable caps with a tapped/switched inductor from their junction to ground. This allows me to tune the grid circuit from 160M - 10M, and the resistive loading is good for stability. Since to drive a class-C amplifier we LIKE harmonics there is no liability employing the T network. It takes about 25 - 30W on the low bands, more as the network becomes lossy at higher frequencies to get 30 mA grid current. (I use my TS-440S as the RF exciter, so no problem there). For a single 4-125 you will need less, of course. GL, -Larry/NE1S __ 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] Re: 810's
Todd, KA1KAQ writes: Rick, it's been a while for me, but the main issue I recall was expansion/contraction, with the envelope heating or cooling at a rate that the glue couldn't match, resulting in cracked tube or broken seal. It's been a long time though, so I really don't recall the particulars. JB Weld is used on engines and other high temp applications as mentioned, so it would probably be fine. I run 810s as modulators and they do get hot, but I doubt it would be an issue. Guys, although JB Weld is good stuff, I'd shy away from it for this application. It's rigid stuff when cured, and if its thermal expansion coefficient differs "enough" from glass, something is going to give, and it will probably be the glass. I'd use high-temperature silicone (like the black stuff they sell for gaskets at the automotive stores), because it stays somewhat "squishy," and so will circumvent the above problem. That's what I'm going to try on an 812A I have with a loose plate cap. JB Weld MAY work out OK, but... 73, -Larry/NE1S __ 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] Re: Amfone.net and the AM Reflector!
Todd, KA1KAQ writes: On 9/5/07, Geoff/W5OMR <[EMAIL PROTECTED]> wrote: It's that darned Larry/NE1S! WATCH HIM! He's -sneaky-! -SNIP- I think he's a witch. Thanks for the kind words, guys ;>) Don't think, for a moment, I won't 'pass it forward', if I get the chance. That's what hams do for each other. Especially AM Hams. (Or at least, they're *supposed* to) You're absolutely right, and it does work that way. An item is only as good as the use it can be put to. You're a prince, Larry. Thanks, again. Aw, shucks. Just havin' fun, and tryin' to spread a little of it around. 73, -Larry/NE1S __ 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] Re: Johnson Valiant Crystal Control Question
Bry Carling writes: If the multiplying scheme for 15m on the Valiant could use 40m crystals X3 then there are many possibilities. 7150 will put you right on 21450 kHz and I have plenty of those available. I wouldn't recommend running AM on 21450 KHz. You might receive QSL cards from an unwelcome source ;>) -Larry/NE1S __ 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] capacitors
- Original Message - Subject: [AMRadio] capacitors Date: Thu, September 13, 2007 10:52 From: "Rick Brashear" <[EMAIL PROTECTED]> > What is the general consensus here on the reflector as to which type of > capacitor should be used in place of the old molded mica capacitors? > If it's really a mica, I'd replace it with a silver mica, or if you need a voltage rating beyond 500V, use a "snubber capacitor" (which I THINK is a silver-mica, made by Cornell-Dublier, sold by Mouser. Usual disclaimers apply). If it's one of those mica look-alike wannabes, but really a wax-paber capacitor (typically vales .01uF and above), replace it with a mylar cap. -Larry/NE1S __ 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] 40m (again)
From: "Geoff/W5OMR" <[EMAIL PROTECTED]> > I'll be back from Houston by the weekend. > > Anyone want to try a 40m sched either Friday or Saturday night? > > -- I do, how about both Friday and Saturday at 10:00PM (to double our odds)? The big rig is still tuned up on 7290. -Larry/NE1S __ 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] Hamfests
- Original Message - Subject: Re: [AMRadio] Hamfests Date: Thu, October 18, 2007 9:36 From: "david knepper" <[EMAIL PROTECTED]> > Has anyone ever considered that our XYLs also enjoy attending hamfests. > My wife enjoys accompanying me to hamfests because of the variety of items > for sale that are non-ham related. My XYL accompanies me to an occasional hamfest. I think she does this because she is amused by all the radio geeks ;>) -Larry/NE1S __ 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] Re: GB> Re: IARU bandplan
- Original Message - Subject: Re: [AMRadio] Re: GB> Re: IARU bandplan Date: Wed, October 24, 2007 12:13 From: "Geoff/W5OMR" <[EMAIL PROTECTED]> > I don't know about you, but "All Modes" to me, includes AM, as AM is a > 'mode' (isn't it?) > Yes, Geoff, it certainly does. But it's the 2700 Hz maximum bandwidth restriction that spoils the party for us. 73, -Larry/NE1S __ 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] Re: GB> Re: IARU bandplan
- Original Message - Subject: Re: [AMRadio] Re: GB> Re: IARU bandplan Date: Wed, October 24, 2007 12:44 From: "Geoff/W5OMR" <[EMAIL PROTECTED]> > I don't know how ya'll, but since AM is allowed as a mode, and it uses > DOUBLE sideband, I'd say we were allowed 5.4kc bandwidth. > Well Geoff, that's one way to look at it. One thing's for sure, I'm not planning on changing MY operating habits based on this hair-brained scheme (except, for, perhaps, to increase my AM activity on the bands a bit!). 73. -Larry/NE1S __ 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] 6U8 Subststute and the 20a
- Original Message - Subject: Re: [AMRadio] 6U8 Subststute and the 20a Date: Mon, November 12, 2007 9:00 From: "jeremy-ca" > Nice setup Jim. Ive had the full range of CE transmitters from 10A to 200V > and everything in between. > > Yeah, Carl, I remember when you were selling a 100V and 200V for $150 for the pair at Deerfield back in the 80s or very early 90s. I'm STILL kicking myself for not buying them both, but that was a lot of money to me back then. I always wanted a 100V especially. I do, however, seem to have "cornered the market" on CE 20As (got four of 'em). 73, -Larry/NE1S __ 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] Re:Reactor Wanted
> -Original Message- > Interesting indeed. > > That approach flies in the face of decades of design convention; as a rule, AM > rigs either use the same supply for mods and final, or as the rig gets bigger, > the mod has it's own supply which is usually a lower voltage than the PA plate > supply. > Greetings, Mr. T! Here are a few random thoughts of mine on this subject. First, I can think of the following arguments FOR using a common power supply. First, cost & space savings. Second, with a choke input supply, the class C final maintains a minimum load on the supply, reducing the size of the choke required to maintain critical inductance. Otherwise, the separate modulator PS would need to be capacitor input, or would have to waste a huge mount of power in a bleeder resistor to maintain the required minimum load on the filter. I think the historic reason for a lower-voltage modulator PS in the case when the supplies WERE separate originates from the conventional wisdom that the audio power required to 100% plate-modulate a class-C final is 50% of the class-C plate input power. But this (1) ignores losses, (2) ignores the "headroom" required for clean modulation, (3) ignores waveform asymettry, and (4) perhaps most importantly, assumes a modulation transformer of the correct turns/impedance ratio can be had. These days, we're lucky find whatever mod iron we can in the power class we need, and build around it. It is often the case we need to run a higher voltage on the modulators than on the final to achieve enough audio voltage at the mod tranny secondary to properly modulate the final, with the iron we are able to scrounge. 73, -Larry/NE1S __ 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] For Sale: Knight T-150
- Original Message - Subject: RE: [AMRadio] For Sale: Knight T-150 Date: Wed, November 14, 2007 17:43 From: "Phil LaMarche" <[EMAIL PROTECTED]> > You don't have to justify what you want for something. If the price is > wrong, it won't sell. Right on! One beautiful thing about free trade is... well, it's free. Neither the buyer nor seller is coerced into the transaction; if agreement can't be found on a price, no transaction takes place. And there's no need for ill feelings on either side, it just means there's a difference of opinion in what the item is worth to each party - which happens all the time! Neither party is "right," or "wrong." Ultimately the item's price is no one's business except for the seller and buyer. 73, -Larry/NE1S __ 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] Spark gap transmitter
>> This is a bit of the subject..Iam in need of a schematic and detailed >> construction notes for a spark gap transmitter..It will be used in an >> upcoming exhibit..Thanks in advance.. > A Model T spark coil, a key and an antenna. > > Carl > KM1H There is usually at least one tank circuit (not counting the antenna itself) involved, as well. (Does the term "jigger" ring a bell?) I'm sure I've got period schematics SOMEWHERE, just don't remember quite where. 73, -Larry/NE1S __ __ 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] HRO-50
- Original Message - Subject: Re: [AMRadio] HRO-50 Date: Mon, November 26, 2007 16:03 From: "Mike Sawyer" <[EMAIL PROTECTED]> > What a pain in the scrote. I agree. Still, when the 1st HRO came out, nothing else on the market could touch it. >The manual says to adjust the coils for the low > end of the band, (in this case, I'm using coil set D 1.8-4.0M GC 3,5-4.0 BS) > and there aren't any adj. available. I looked in the in each coil set and I > can see the coil but it looks as though it was designed not to be adj. and > I'm hesitant about attempting to adj. them. For the low end of the bands there is a 1/2 turn on the INTERIOR of the coil form that is to be moved either to buck or boost the main winding, or anything in between. "Pain in the Scrote" sums it up pretty well ;>) How you are supposed to make slight adjustments, noting the output level, pull the coil, poke that 1/2 turn a bit, again note the output level, and ultimately find the peak is beyond me. I usually optimize at the top of the band (where trimmer caps are accessible with the coil installed at the top, and watch the output level as I adjust) and take what I get at the bottom of the frequency range - life is too short! Maybe when I retire I'll do the PROPER alignment on my 2 HROs, if I run out of stuff to do... 73/GL, -Larry/NE1S __ 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] HRO-50
- Original Message - Subject: Re: [AMRadio] HRO-50 Date: Tue, November 27, 2007 15:48 From: "jeremy-ca" <[EMAIL PROTECTED]> > We got plenty of all era HRO's in for service and a jig was not used. Once > you got the knack it was easy. The holes in the chassis are there for a > reason. > Hi Carl! Are you referring to the holes in the TOP of the chassis for the high-end adjustments, or holes in tha back of the coil rack, under chassis, for the low-end adjustments? Neither of my HROs (a 2.5V heater 1935 model, & and HR0-7R) have the latter, so the coil racks need to be removed for the bottom-end-of-range adjustments. I do understand certain models had them, but mine don't :>( 73, -Larry/NE1S __ 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.
