Re: [AMRadio] Re: AM Exemption Already Drawing Fire
Thanks Jim, I went back and looked at the document, and the document I saw on the ARRL site had no RM number or otherwise (the RM- was suspiciously blank although it certainly looks correct in every other way), so that is the trouble I am really having. best regards, Patrick From: "Jim Wilhite" <[EMAIL PROTECTED]> Pat if you want to look up the comments go here http://www.fcc.gov/cgb/ecfs/ On the top right is a pane called ECFS Main Links. Select "Search for Filed Comments. Put in the number of the RM or whatever that other designator is and submit. 73 Jim W5JO
[AMRadio] Ladd Electronics
Original Message Subject:[HDXA-NI0DX] Ladd Electronics Going out of Business Sale Date: Fri, 02 Dec 2005 17:52:10 -0600 From: Jeff <[EMAIL PROTECTED]> To: HDXA <[EMAIL PROTECTED]>, BARC <[EMAIL PROTECTED]>, AKSARBENtalk <[EMAIL PROTECTED]> I stopped in to see Frank today only to discover that he is closing his doors at the end of December. He found out yesterday that everything must be out of the 3 story building by the end of the month. WOW!! He asked my to notify as many hams as possible to stop in and make him an offer on anything. He's an Icom dealer, but has many used rigs both HF & VHF. Amps, transceivers, receivers, antennas, used surplus, parts, magazines/books, you name it and he probably has it. Frank also will sell the entire inventory as well. He told me that he will sell $20k of inventory for $10k. Please spread the word to as many hams as possible and stop in to bid Frank Ladd and his many years of service good-bye. Ladd Electronics 111 N. 41st Street Omaha, NE 68131 402 556-3023
[AMRadio] Re: AM Exemption Already Drawing Fire
Sorry if I asked before, but does anyone know the url to the FCC document where these comments about the new rules and bandwidth are supposedly available? Not the ARRL site, but the actual FCC page? I can't seem to find this mysterious document anywhere. Thanks, PJ
[AMRadio] Re: AMRadio Digest, Vol 23, Issue 12
solid state mixing with tubes.. I tried to fire up an old tube linear for test with an Alinco DX-70.. The Johnson Viking I usually use for this was not within reach and the DX-70 was. Unfortunately, there was a DC connection between the GG amp cathodes and the RF input jack. Somehow this fried the Alinco and blew the fuse on the linear.. I think when I did the forensics on this one that when the Alinco un-keyd, the amp was still keyed and 300VDC appeared momentarily on the RF input jack -still not sure why, but it did. PJ -- From: W5OMR/Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Valiant and Loop progress Paid yer dues? Brother, you ain't got started good, yet! ;-) Wait till ya try interfacing tube technology with solid state stuff...
[AMRadio] Re: AMradio -tubes and transformers site up again
I've put the transformer catalogs and tube manuals online at b u n k e r o f d o o m d o t c o m, just put it together, and have a look. (sorbs.net likes to block innocent e-mails and then try to extort ISPs for unblocking them, so that is why I have spelled the name as it is.) 73 Patrick [EMAIL PROTECTED] wrote: Send AMRadio mailing list submissions to amradio@mailman.qth.net To subscribe or unsubscribe via the World Wide Web, visit http://mailman.qth.net/mailman/listinfo/amradio or, via email, send a message with subject or body 'help' to [EMAIL PROTECTED] You can reach the person managing the list at [EMAIL PROTECTED] When replying, please edit your Subject line so it is more specific than "Re: Contents of AMRadio digest..."
Re: [AMRadio] Need Transformer Info - Chicago Standard P-67
I sent you the pages rom the catalog off-list, please let me know if you got them. Patrick From: David Hollander <[EMAIL PROTECTED]> Subject: [AMRadio] Need Transformer Info - Chicago Standard P-67 Transformer Does anyone have the specs on a Chicago Standard P-67 Transformer? Tnx and 73, Dave N7RK
[AMRadio] Re: FS: Parts EFJ, Millen, Bud, RCA, UTC, Thordarson, More
I just got assigned to serve EFJ in a technical capcity as one of my customers. WOO-HOO! Not the same core, most of the engineers did not make the move to Texas. Still, some of the very finest commo gear, as would be expected. Re: FS: Parts EFJ, Millen, Bud, RCA, UTC, Thordarson, More
Re: [AMRadio] Amp / Tube question
Probably a bad tube, any 3-500Z should be fine in there. Sometimes, an abused one will have a deformed grid from overdriving, and it's too close to the plate, or one of the grid wires is broken and sticking out towards the plate, and it can arc. Or the tube could have some gas in it, causing an arc. Had this happen with a few old used tubes before. I even blew a fuse on a bias supply with a 304TH that had a grid-filament short once. If you are worried, you may try next time to put perhaps a 2 to 5K/100 to 200 watt resistor in series with the plate of the tube and the plate cap of the amplifier, just to check, for a test only. You can lay the resistor on a piece of wood or other insulating material, and use 10KV test probe wire, or just route the leads so they are away from other things. This is very dangerous and must be done with great caution of course, and only for a few moments. -but then the arc in a bad tube will only be pretty, and not destructive (hopefully). -and you can just shut off the amp if bad things happen. Patrick From: John Lawson <[EMAIL PROTECTED]> Subject: [AMRadio] Amp / Tube question Shut it off, put on the plate cap, hit the power sw - BAM! as Emeril might say. A large blue flash went off in the tube and I welded the line fuse to it's cap. And smoked the meter dropping resistor - though it's been replaced before, I see.
[AMRadio] The price of tube type mobile linears in China!
I've been collecting tube mobile linear amps for a while.. Just the old tube type ones, most of which were sold as 10 meter or 10/6 meter amps, or just outright as "CB leen-yars".. but now for whatever reason, the things seem to be getting more costly, despite the high price of sweep tubes (which are usually always bad in them).. I used to pay $10-20 for the old things, even $50 or a bit more for a nice one, and now some people are wanting $50 for a chopped-up old 100W PEP beater "as-is" with holes all over it and fans hanging off it everywhere! I don't mind paying a fair price for something, but wow! Oh well. I did turn down a nice HA-250 recently for $50, but only because the guy would neither guarantee it nor let me hook it to 12V before buying, and I thought that was suspicious. Anyone got any lying around, small or large, homemade or factory, all frequency bands acceptable, they would let go reasonable? PJ
[AMRadio] Re: BTA-1R in Texas
The unit is sold, Thanks to all that volunteered! PJ
[AMRadio] BTA-1R in Texas
My friend has to sell his RCA BTA-1R. please do not reply to me. see below. ] RCA BTA-1R AM BCST transmitter $200 cash Mr. Scott Rice 307 N Beverly ST Longview TX 903-720-0184 output: 1000 watt carrier level / 4KW PEP AM 525 to 1600KC dimensions: 84" x 32" x 34", 1500 LBS, consumption: 208-240VAC 1 phase, 2900W / 4200W @ 100% sale conditions: first person to show up with the money and a hauler gets the rig. transmitter in home garage - you pick up. ASAP !! Surely someone can get this picked up next weekend or so? This is not a junker, it must go only because the classic car must enter the garage instead. also available: two 1KW FM broadcast transmitters -identical. one works, one is for parts. best regards, Patrick
Re: [AMRadio] ARRL has filed its bandwidth proposal with FCC
It does not seem as though they deliberately relegate AM to a footnote, it looks more like the effort is only to give AM its due, while keeping the "hi-fi SSB" stuff at bay. That's what I see anyway, between the lines. They could have as easily put the AM exception statement in each cell of the table, then it would not be a footnote, but that would have messed up the table and beaurocrats like nice orderly documents. VE VILL HAFF ODAH!! I think we should be glad for the '9K' limit on AM and not make too much noise lest they decide 6K00A3E is the legal limit! problems, however: No ISB. why? maybe because of the 3.5KHz rule.. So much for the Harris Monstrosity I am trying to obtain. It can do voice on one sideband and data on the other. I know it's a military specialty, but it's nice! And I would like to see the rules for AM go back to the traditional "KW input". It's no good for a 4-1000 to operate at 2000V and boil off all those electrons from the filament and not use them! Wishful thinking I suppose. -but the upside is I can use the absolute worst pulls!! http://www.arrl.org/announce/regulatory/bandwidth/Bandwidth-Minute-64-Petition-FINAL.pdf Who's running the ARRL and FCC anyway? :) PJ
[AMRadio] Re: Need list of good AM radios to start looking for . . .
I'm a bit biased, as a tube audio guy, but I would go for a transmitter that has a push-pull plate modulator for the final. For the receiver, find one that is double conversion or better and has selectable bandwidth via LC filters and a crystal filter. tuned circuits are not so sharp, but sound real good when wide open on a strong signal! The Hallicrafters SX-28, to me, is one of the best sounding AM receivers but they drift a bit and are not that sensitive. Can be pricey too.
[AMRadio] W5PBN I. "Frank" Miller
My elmer, Frank Miller is in the hospital. Please have a thought for him in these next few days as he is in his 80's and will have surgery Friday. Patirck J
[AMRadio] Re: GB> Fair Radio puzzle
God is just a prayer away... ... and a couple hundred volts is all it takes to meet Him. my safety motto.. inspired by that post in their catalogs.
[AMRadio] Re: AMRadio Digest, Vol 21, Issue 14
ahh, but that's the mystique of CB radio, is it not? From: "Donald Chester" <[EMAIL PROTECTED]> And gets you a lot of splatter and distortion too. -DC --
RE: [AMRadio] GG 813 Linear in GE Ham News
This scheme is also taken even further into the cutoff region in CB-land and used to obtain a low level carrier, say 1 watt, while still obtaining 12 watts peak envelope levels at full modulation. A radio or amplifier set up to do this is called a 'modulator', and gets you alot of 'swing' on the old power meter. Just don't take it too far. PJ > >>> >I increased the bias on it so to the point just > >> beyond cutoff for AM so > >>> >that >>> >it requires a little more to drive and it reaches > >> negative 100% modulation > >>> >slightly before the driver does.
Re: [AMRadio] old transformer catalogs are back online
It's ADSL and the speed out to the internet is 384K bits per second. That's all there is here. Patrick Date: Tue, 4 Oct 2005 18:34:43 -0500 From: "Jim Wilhite" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] old transformer catalogs are back online To: "Discussion of AM Radio" Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original I agree with Pete. Even on DSL it is slow. Is it the data or the server? 73 Jim W5JO
Re: [AMRadio] old transformer catalogs are back online
I hate to make a problem for dialup guests, but the scanning results themselves dictate somewhat large file sizes. My goal is to have them nice enough to print, and retain the original character of the documents. The 325K picture is not bad compared to a page of one of the catalogs, they are high resolution, an average of 200K per page at about 1500 pixels wide. They were scanned at 300DPI, and the image resampled down from 2500 to 1500 wide. I do not prevent 'deep linking' or force entry by way of a specific page, so there is no need to view the image once the URL of the transformer index is known. Here it is: http://www.bunkerofdoom.com/Litterature/OTC/index.html I do appreciate the comments, maybe I can see about downsampling the image. Patrick Date: Tue, 4 Oct 2005 18:19:20 -0400 From: peter markavage <[EMAIL PROTECTED]> Subject: Re: [AMRadio] old transformer catalogs are back online To: amradio@mailman.qth.net Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=us-ascii The loading of the picture, in order to get to the info, will make a dialup person cry. Pete, wa2cwa On Tue, 04 Oct 2005 17:10:33 -0500 Patrick Jankowiak <[EMAIL PROTECTED]> writes: Hello, The transformer catalogs are back. http://www.bunkerofdoom.com/ (just scroll down below the picture) If anyone finds an error, please let me know. PJ -- __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net End of AMRadio Digest, Vol 21, Issue 7 **
[AMRadio] old transformer catalogs are back online
Hello, The transformer catalogs are back. http://www.bunkerofdoom.com/ (just scroll down below the picture) If anyone finds an error, please let me know. PJ
[AMRadio] Re: Minature Mobile Transmitter
What I don't get is the tube current ratings, and, was tube life a concern? 300V zero bias gets you 8mA per section, and is also 2.4 watts dissipation! I suppose these are the ICAS ratings :-P -and that's zero signal. The curve is very linear from 2mA to 8mA and even pretty good down to 1mA idling current. -but those would take bias. PJ
Re: [AMRadio] GG 813 Linear in GE Ham News -12AT7 12AX7
don't laugh too hard, In the ARRL handbook it claims 8 watts audio from an 12AX7 in zero bias class B push pull into 8000 ohms. I have never understood that one, if you look at the currents stated in the book, they seem pretty high for the tube. PJ
Re: [AMRadio] GG 813 Linear in GE Ham News
The figures are about right, half the rated dissipation is about what carrier level should be. I used to run a pair of 813's in parallel, zero bias GG on AM. carrier: 2200 volts 150 mA 90W out 240W dissipation and the tubes ran with color allright! "single tone" 2000 volts 300mA 360 W out 260W dissipation (brighter color) something was never quite righ with the efficiency in that amplifier, but it was running close to the max. frequency for the 813 and they are not too efficient there. A big fan on the bulb works wonders for the 813. PJ
[AMRadio] Belton
I regret I cannot make it, someone is coming over to pick up alot of junk, so it is best for me to be here Saturday if I want the place cleaned up for free. PJ From: W5OMR/Geoff <[EMAIL PROTECTED]> PJ, you gonna be at Belton HamFest this weekend?
[AMRadio] Re: Ameritron ATR-30: conclusion
I returned it today. no hassles. my 'official' review is on eham.net http://www.eham.net/reviews/detail/55 Time to just build one.. with decent parts. Patrick
[AMRadio] 208.190.133.201 website coming back online, finally
Remember the old 208.190.133.201 website with the transformer catalogs etc? well maybe maybe not. Anyway, I have the new server running, but not much content yet. I would appreciate if a few people would have a look through this series of pages and comment on whether all the images load properly, how it sems to work, broken things, etc. I think it's OK, but there are a few funny things going on, like sometimes thumbnail images not showing up promptly, at least on my PC. http://208.190.133.201/tuckerkw/tucker_transmitter.html thanks in advance, Patrick
Re: [AMRadio] Ameritron ATR-30
Deric, that's nothing compared to what I have been mumbling.. I've looked at the AT5K, and see the ceramic body inductor. That is what I want, or an inductor with alot of taps and a big switch. I've heard of the wheel on old ceramic body inductors occasionally jumping the track if the thing gets dirty, but otherwise, I've seen these kind of inductors 40 and 50 years old and still working properly once cleaned and lubricated. For now, after I return this contraption, I'll use an old tuner I built in the 80's, which will handle a 100W rig easily, and be done with it. It does not have a balun, but maybe I can make one, apparently, by winding enough turns of RG-58 around a suitable form such as a 5" PVC pipe (as suggested in a book/website or two) I will not condider an AT4K because the inductor (current production model) looks like the same or similar design apparently as the MFJ, er.. Ameritron ATR-30, and there are negative comments about the inductor if the 4K. I have done some research on tuners, and my initial impression about the AT5K is this: The price is high, but might be OK if it's as good as it looks, and the customer service rules etc seem a bit less friendly at first look. I'm not sure it's worth the money really. That is, a unit with a better switch and inductor should be $500, not $1000. So I'm not really sure what to do. Maybe I just need to start looking for the appropriate parts. It's not rocket science, and then I can have a real chassis and thick front panel, etc. If I need fancy metering, nothing would stop me from making use of an old Drake 2KW unit I have sitting right here. I don't care if it is big, that's what racks are for. PJ ]]] From: peter markavage <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Ameritron ATR-30 The Palstar AT4K or 5K is what you need.Built like a battleship. Their web site is here: http://www.palstar.com/ Pete, wa2cwa
[AMRadio] Ameritron ATR-30
Ok, so I went and bought one because I need one for some TXSG HF stuff and decided to go ahead and get the biggest and best one I could find locally. What a P.O.S the thing is! It came in what I assume was a factory box, but inside the box: The thing was rolling around loose inside the box with apparently only some of the packing material inside. The AC adapter was loose; apparently it had been removed from its sealed box by some little elves or something, apparently more than once. Its box was loose, and ripped up. Also said MFJ on it. The front of the tuner has little scratches and marks on it, and the chassis looks warped, either that or the top cover does not fit correctly. Beat up in shipping? The inductor seemed OK at first, but now binds up at a spot in each turn. after about 15 tuning cycles. I found that the cheaply made thing has a shaft down the middle, on which a support at each end holds another shaft, upon which rides what is basically a pair of spring-loaded washers which grip the edge-wound inductor between them as they spiral up and down the inductor, and that one or both ends of this shaft were askew because the screws in the supports that hold them to the main shaft (and secure them radially, like a knob is secured to a shaft) were loose. tightening them was no good because they apparently have been tightened before, and it's all screwed up and seeks this skewed position after several traverses. What ever happened to keys and pins? what a cheap piece! Additionally, the feel of the inductor is rough, not smooth, and the knob is very cheap plastic. Also, plastic gears for the turns counter do not impress me, especially when the shaft of the turns counter is not aligned properly at manufacture with the gear on the inductor shaft and is obviously under some stress. -sloppy work! Speaking of the workmanship, while I am at it, the front panel of the inductor assembly is not mounted parallel to the front panel of the unit. I am not talking a thousandth here, I am saying it looks like some drunk with a grudge against radiomen put this thing together! Strangely, the rear of the inductor is straight. The cermaic insulators on the rear have metal-to-ceramic contact between the nuts and the ceramic. I didn't notice this until I tried the balanced line tuning function. then of course I heard the 'grinding' sound I am sure we all know. Where's the fiber washers?!?! The antenna selector switch also has a rough spot in it, but only when turning it one way between this position and that position. I could not find the cause. And while I am on about the switch, I cannot believe anyone would want to run 1500W 100% carrier through that little switch -that's 5.4 amps of RF at 50 ohms, through what looks like a 3A switch with a ceramic wafer! It is what is claimed. (3KW PEP, 1500W FSK/carrier) OK, I called the merchant I bought this from (I walked into their store today and plunked down $500+ for this thing) and they have no idea about the packing or otherwise. I asked them if it was a refurb, they said no, it was new from Ameritron. So, Monday, I am going to contact Ameritron, and let them explain to me why I should not return this thing. Come to find out, from the merchant, it's same as MFJ! darn it, I am trying to buy something that's rugged and well made. But wait - I am stuck with this now for a couple weeks to use it for TXSG commo. I'm still going to call them on Monday and have a word with them about it. Seeing all the corners cut like that, I don't want this thing. It's not what I paid for. This is the biggest example of POS workmanship and poor mechanical design I have ever seen and that includes most CB shops I have frequented in the past! Maybe MFJ knows how to build little 300W tuners, but they are out of the loop on ones this size. It has the mechanical robustness of an AM clock radio - which is fine for a 300W PEP tuner. I'll keep it only if they want to give me a lifetime warranty including overnight drop-ship replacement and return label in perpetuity. disgusted, PJ
[AMRadio] BC-610 XFMR
I apologize, I don't hace it anymore. I went to look at it, and remembered I let it go with a KW 2M amp last year. I must be getting oldzheimers' or something. From: Patrick Jankowiak <[EMAIL PROTECTED]> If anyone wants a BC-610 transformer, ...
e: [AMRadio] Drying out HV transformers / Chokes
If anyone wants a BC-610 transformer, I have one good one, trade or reasonable, but no BC-610 to put it in. Shipping is going to be the problem. PJ
[AMRadio] Today's Xtreme racksports
Put most of the big power supplies in a rack today. This should help when I want to build or repair something. I think it's pretty! http://rawfire.torche.com/~opcom/medpsu/index.html AM content: these can be tweeked to become series modulators for low power AM PA's.
Re: [AMRadio] what is this old power supply?
Too bad the rest of it is not around.. I may try to probe it out, are we reasonably sure this is 50/60 Hz and not 400HZ? One website said the unit ran off 12/24VDC but there must be a missing link there. Looking at resistances of windings, I suppose the 'zero ohm' ones would be heaters, and the 5-10 ohm or so would be 220V, then the 100-300 would be B+. I would really like to see if I can trace it all out, and maybe put it to work somehow. The big transformer seems to have two HV windings and one LV, and then there is another smaller transformer with an awful lot of terminals. lets see: 1. 5V 4A CT for the two VT-145 on the top B+ 2. 5V 2A for negative side VT145 #1 3. 5V 2A for negative side VT145 #2 4. 220V AC in 5. maybe 6.3V at ?A for something else. I am baffled at why the chassis has 20 terminals if it only has B+ hi/lo, etc.. Anyway, the only thing to do is get out the variac and go a-probing.. PJ From: [EMAIL PROTECTED] If it says A*M with the crown, then that is British Admiralty equipment... Could it possibly be a power supply for a T1154 Transmitter? From: Geoff <[EMAIL PROTECTED]> T-1131, from what I found.
[AMRadio] what is this old power supply?
I've found a power supply, green front panel, rackmount, sockets for four VT-145 tubes. label #1: POWER UNIT TYPE 5008/9 REF NO 110K/525 A*M NR 2080 (the * is a symbol of a crown) label #2: SIGNAL CORPS U.S. ARMY POWER SUPPLY PANEL PN-12A It looks like high and low B+, and filament supplies for something. On the rear chassis face is a big ceramic terminal for the high voltage and a long terminal strip of about 20 terminals for everything else. Has 2 chokes A27094 transformer A27090 transformer A103004 Anyone know what this is part of, and where a wiring diagram might be had? It is weighty. Thanks, Patrick
[AMRadio] Re: W4QCU Homebrew AM rig
that is a beautifully made radio set! PJ
[AMRadio] how-to fix a ceramic/metal air variable capacitor
This is not specifically related to either list, but I thought I would show how I just fixed a snall transmitting air variable cap. I hope it is helpful to anyone who has had this happen. If nothing else, it saved me from having to use a substitute or take one from another complete radio set. Repairing the cap: http://rawfire.torche.com/~opcom/caprep/index.html Here is a rack of nice ITT FAA AM and GE FM commo gear I just put together. http://rawfire.torche.com/~opcom/uvrack1/index.html It's too hot outside, so been playing indoors... Patrick
[AMRadio] Re: AM Audio
Hmm.. 100mA for the pair; Maybe 3300V-3400V? If so, you should not be short on modulating power ;) Question is, how do you deal with the large DC voltage difference across the mod xfmr? is this not a risk? nice. pj From: Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Re: AM Audio To: Discussion of AM Radio Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Hey, do some calculating... That's -70V bias on the 250TH's, resting at 100mA of idle current. Yes, the rig is -on the air- in that shot... That's also about 300mA on the final, and the final is running around 1500vdc at that time, I think... regardless, for 250TH's with -70v of bias, to have 'em rest at 100mA... how much plate voltage do you think was on the modulators, at that time? -- 73 = Best Regards, -Geoff/W5OMR
[AMRadio] Re: Choke calculations
Now THAT is the key to happiness! Since we might wish to also measure the inductance of a choke with some amount of DC current flowing through it, does anyone have an idea how to do this? In an example of a 10H choke, which would have 3768 ohms impedance, how would I pass 0.5 amp through it's 80 ohms of DC resistance without messing up the impedance measurement method? To me the obstacle looks like the issue of the power supply feeding the choke having a very low impedance compare to the measurement value to be made. Add to this the desire for a range of 0.1 to 100H and it's a real issue, at least from a calibration standpoint. I am certain some one on this list has done this before. It has to have been done in the choke factories of olden times! Patrick From: "John Coleman ARS WA5BXO" <[EMAIL PROTECTED]> Subject: [AMRadio] Choke calculations To: "AMRadio" Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="us-ascii" Hey Bob: I just realized that each Henry of inductance is equivalent to 376.8 ohms at 60 Hz. I don't know why, but at my age now, little revelations of that nature excite me. John, WA5BXO
[AMRadio] Re: AM Audio
Geoff, That is a beautiful rig, with those plates all a-glow! Patrick From: Geoff <[EMAIL PROTECTED]> Subject: [AMRadio] AM Audio To: Discussion of AM Radio Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Well, I completed the task yesterday of installing a Reactor for the 250TH rig. (Push-pull Class C 250TH link-coupled final, modulated by push-pull Class B 250TH modulator) http://w5omr.shacknet.nu:81/~w5omr/hamstuff/AM-Stuff/Titanic/modulator/new_titanic.jpg
Re: [AMRadio] RA-1000
No such thing as an ugly broadcast transmitter. Maybe Raytheon was thinking of the styling of military gear when they chose the appearance. PJ From: VJB <[EMAIL PROTECTED]> Subject: [AMRadio] RA-1000 Personally, I don't find the Raytheon "ugly" but its sense of fashion does tend toward utility rather than glamour. I wish they had included a window to observe the 833A.
[AMRadio] Re: KD5OEI
Hey Geoff, I didn't take anything the wrong way, or from Bob's post with the good buddy either (although I did feel compelled to reply to that one!). No skin off my nose, all is good. I gotta fix up them rigs.. soon soon.. at least they are un-buried. PJ Date: Tue, 16 Aug 2005 18:24:04 -0500 From: Geoff <[EMAIL PROTECTED]> Subject: [AMRadio] KD5OEI To: Discussion of AM Radio Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=us-ascii; format=flowed It's come to my attention that I may have shed some negative light on a fellow enthusiast, Patrick Jankowiak/KD5OEI.
[AMRadio] good buddies and viruses
Guys I'm sorry for that third CB dictionary link. I didn't scroll down past the dictionary, and had no idea what was there. don't look! sorry, kick me off the list, PJ
[AMRadio] good buddies and viruses
Bob, There are no viruses attached to the UNIX server on that link, must be something wrong with your PC. Do you know what "good buddy" means today? http://www.geocities.com/TheTropics/1608/page2.htm http://www.lemoi.com/trucker/truckslng.html http://www.wackbag.com/showthread.php?t=18594 that's not nice. PJ From: "Bob Maser" <[EMAIL PROTECTED]> Your link to the pic has a virus attached to it good buddy. Bob W6TR
[AMRadio] Re: The Tucker KW
On the 6M rig xtal frequencies are: TX freq / 32. RX freq - 5. The book says: "The (RX) crystal oscillates on its third mechanical harmonic and is ground especially for use in this circuit". The IF is 5MC. so it is really: (RX freq -5) / 3 Hmm. So do most crystals oscillate on their third harmonic well? == On the 2M rig, don't know yet about the architecture. PJ From: Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Re: The Tucker KW Patrick Jankowiak wrote: Well I have worked all day Saturday (just quit now 1AM!!) doing more cleaning in the lab. I now have the Link 250UFS, the Tucker KW, and the BTA-250L all next to each other. There are my 6M tranceiver, 80-10 xmtr, and 160M xmtr respectively. The Link is FM, but I bet I could amplitude modulate it. Not sure if I want to. Is there more activity on 6M AM or FM? Not sure, in the North Texas area. What's the consensus on freq. choices for VHF rigs that are basically fixed-frequency (meaning they take alot of hassle to re-tune)? What are the good manners for that? The simplex frequency? For the VHF rig, and in keeping with staying off of the simplex channel 24/7, build up a xtal switch. If you've got more than one frequency pair in mind (most repeaters all nowadays use a PL tone for access, so you'll be better off on simplex with that rig, anyway) you can use the switch to move to whatever you have available to you. just some xtal sockets mounted on an aluminum chassis, and a rotary switch. That's how I've seen it done, even using the old Federal police transmitter/reciever combos. Back in the late 50's early 60's, those were some 'boat-anchors'. Seperate transmitter, with a 2E26 in the final, and a seperate reciever, both on slides in one small(ish) box and a control head to the dash, with a cable as big as a horse-... well.. you get the idea. I have a couple of good stable PLL based 0.5-80MHz VFOs (lab gear) that I could sub for RX and TX crystals if necessary. Talk about having to keep charts.. No rush though, still alot of cleanout left to do. What's the rig use in it? A frequency double-tripler circuit in the transmitter? What's the IF freq of the reciever? Some recievers use a simple tripler scheme. A calculator exercise I performed with regularity, was the xtal freq of a Regency HR-2A. Freq - 10.7 (IF) / 3 = Xtal freq 146.64 - 10.7 = 135.94 /3 = 45.3133 so... 146.52 would mean it's need a 45.273 xtal or, something that's going to oscillate at that frequency.
[AMRadio] HMBA's in a 'lineup'
Here are the three heavy metal projects as they are right now. Finally getting the lab cleaned up enough to put things sort of where they should be. http://rawfire.torche.com/~opcom/kd5oei/index.html Anyone know where to find a 30" rack panel for the bottom of the Tucker rig (in the middle)? Apparently this is or was a standard size, but darn if I can find any. A nice note for silent cooling: The 24 volt DC blowers taken from scrapped Digital Equipment Corporation "VAX 6000" series of computers move a ton of air at 12V and are nearly silent. These old machines are now mostly kept by resellers only, and for parts only. Normally I would never suggest tearing up an old computer, but they are going into the crushers everywhere. The blowers should be dirt cheap! If you can get the front blower, it comes off the machine attached to a ready-made intake plenum, and will sit right on top of most racks. Although the blower is designed to mount with the wheel shaft horizontal, the assembly can be placed flat with the plenum on the rack-top, and the hot air gets sucked up and blown out through the circumference of the wheel. When placed this way, the plenum box is about 12x18x4" tall. The blower assy adds 3". PJ
[AMRadio] Re: The Tucker KW
Well I have worked all day Saturday (just quit now 1AM!!) doing more cleaning in the lab. I now have the Link 250UFS, the Tucker KW, and the BTA-250L all next to each other. There are my 6M tranceiver, 80-10 xmtr, and 160M xmtr respectively. The Link is FM, but I bet I could amplitude modulate it. Not sure if I want to. Is there more activity on 6M AM or FM? I need to get the BTA-250 off the cart it is on, but I might need help because it is sort of heavy. I got it on the cart myself, but it was a bit tedious. Next is to take the original tube repeater from the Irving ham radio club, and mount it in an old motorola police radio cabinet, and set that next to the Link. I am not quite sure what frequency to put it on, however. Hate to stick it on the calling freq., and not be able to move off it, but that might be the best bet. What's the consensus on freq. choices for VHF rigs that are basically fixed-frequency (meaning they take alot of hassle to re-tune)? What are the good manners for that? The simplex frequency? I have a couple of good stable PLL based 0.5-80MHz VFOs (lab gear) that I could sub for RX and TX crystals if necessary. Talk about having to keep charts.. No rush though, still alot of cleanout left to do. Should I post a pic. of these things lined up? PJ
[AMRadio] Re: The Tucker KW
Hi John, IIRC, it has on the screen terminal of the socket, several disk ceramic caps in parallel, along with a rectangular mica cap about 1"x1.5" square. The leads are as short as possible. The filament also has one side connected directly to ground with a fat copper strap. I have to go look at it, maybe this weekend and give an answer more accurately. (right now it is behind a huge stack of DEC litterature a friend is picking up to scan SAT morning.) I certainly can use those chokes, if they are the ones I recall, they are these big ones with ceramic terminals that had at one time some er.. 'oil' splattered on them? I only have 6H in the power supplies and would like to replace the ones I have subbed in because they are questionable for the voltages. Please let me know about the Raytheon chokes, I'll report on the rig as soon as I can get to the backside of it and remove the panel. Patrick From: "John Lyles" <[EMAIL PROTECTED]> Subject: [AMRadio] The Tucker KW To: amradio@mailman.qth.net Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="us-ascii" Patrick What sort of bypass caps does the screen connection have. How long are leads? I would try to put a good VHF bypass in there, if possible, something with very short leads to chassis from the tube pins. One cap that comes in mind if the American Technical Ceramics 100E style leaded chip capacitor. It has wide strips for leads, very low inductance. 390 pf value tends to have zero impedance at 200 MHz (self resonance) and higher values look like an excellent RF short at correspondingly lower frequencies. You can check the ATC website and see a chart of impedance versus frequency for these caps I believe. In addition to the ATC cap, have some good lower frequency bypass like two x 5000 pF or so in short leads ceramic disk or doorknob style RF ceramic RF caps (5 kV). A series grid 'stopper' resistance isn't a bad idea, but you shouldn't need that high a value (much over 50 ohms) if it is working. I would be suspicious of the anode circuit having a parasitic resonance that is getting back to the grid and regenerating. I cannot remember from the photos if it had parasitic suppressor on the plate lead? I never shipped you those Raytheon RA1000 power chokes, do you still need one or two to replace the one with broken studs? 73 and good luck with the 4x1K John K5PRO New Mexico
[AMRadio] Re: How can we rid the HF bands of AM ?
From: Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Re: How can we rid the HF bands of AM ? To: Discussion of AM Radio Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Patrick Jankowiak wrote: Hey Geoff, You are right, I won't be totin' the Tucker KW or even the BTA-250.. For me the AM is a hobby and a love for doing things in one of the old and respected ways. No General yet, maybe soon. I have alot of fun just fiddling with them. You like fiddlin', and that's fine. But, for me (and I think some others here agree) there's nothing finer than saying "rig here is homebrew" and getting that "man, that's a good sounding rig" report in return. The feeling is indescribable. I can relate to that. First time we cathode-modulated Dennis W5FRS's homebrew 250TH amp with an Altec 1570B tube amp, we were ecstatic over the reports. I think the one that got me was "sounds just like a broadcast station". We did tweek the amp quite a bit to get the modulation linear, It was originally running AB2, and we had to increase the bias and drive, and load it a little less, but it sure did sound sweet. Some pice are here: http://rawfire.torche.com/~opcom/dbrady1/index.html The Transmitters/restorations are on hold as I am doing a major clean-out of my lab. Each weekend we have been hauling 800 lbs of junk to the landfill, it is -most- politically incorrect. nothing of interest here, unless someone wants old 9-track computer tapes and stuff like that. You never know what someone will buy on ebay. At worst, it hangs around your shop another week. At best, you have something that someone else thinks is an antique relic and is 'just the part' they need to finish out their collection. *shrug* hey, it could happen ;-) I tried to sell a 450TH, appearing as if it was unused, no scratches on the base - asked in here for $50 for it, in the metal spring-loaded shipping frame, in a box. No one bit. Put it on ebay for 7 days, and started it off at 9.95 and it sold for some 3X (plus shipping) what I was asking for it originally, in here. The worst than can happen is, it hangs out for a week. A 450TH is a very specialized tube today. Sometimes it takes just the right buyer. $50's cheep cheep for a new one, I think. For what was lost, well that is true to a degree and 3 or 6 dB does not make that much difference at the other end, but I guess I am looking at the old Tucker rig and knowing its audio and RF power supplies are good for 3KW DC each. COL Tucker built it for military communications from Dallas to Austin. I mean, the thing was/is capable of who knows how much audio input on top of the KW DC. I'm thinking of the peak power. It just seems a shame to idle it out along the wireless in 2nd gear. The upside is that it will probably last forever. Think of the money you'll save on spares ;-) Well you have that right.. once all the bugs are worked out. I did go through a few of 5R4's in the modulator bias supply before I figured out that one of the 304TH's had an intermittent short from filament to grid, but only with HV applied. Oddly, whatever happened 'blew up' the filament in the 5R4 before any fuses or overloads could trip, and then the bias supply fuse blew.. This was in a supposedly good 304TH I bought from ebay. Due to the scarcity and high costs of 304TH's, I have changed to 3-500Z's now, and I need to re-do the bias supply for 0-30V instead of 0-300V! I think a 10:1 voltage divider/bleeder drawing about 100mA at 300V should do (The modulator bias power supply is rated 200mA). That way the rig stays more original, and the grid supply now has a 300 ohm resistance! The status on that beast is that there is a parasitic oscillation in the final's grid circuit, between the 4-1000 control and screen grids, at about 140MHz. Plate tuning, current, and neuralization setting do not matter or vary much at all with this issue and the grid current and screen current interact alot. I found that a 50 ohm resistor in series with the grid helped. Maybe I need to increase that value or I don't know.. The screen grid is heavily bypassed directly at the G2 terminals on the socket, and an RF choke is optionally in series with the screen to the chassis connector to no effect. This oscillation happens no matter if the grid drive connector is shorted, open, or terminated, so this tells me it is in the control grid circuit somewhere. Nothing's been changed from the original design there, so it is further mysterious. Just for grins and giggles, try putting 2 50 ohm resistors in series to ground, and then the grid to the center of the two 50 ohm resistors. It's helped other rigs. I will try that. I am not sure of the effect it will have with the gr
[AMRadio] Re: How can we rid the HF bands of AM ?
Hey Geoff, You are right, I won't be totin' the Tucker KW or even the BTA-250.. For me the AM is a hobby and a love for doing things in one of the old and respected ways. No General yet, maybe soon. I have alot of fun just fiddling with them. The Transmitters/restorations are on hold as I am doing a major clean-out of my lab. Each weekend we have been hauling 800 lbs of junk to the landfill, it is -most- politically incorrect. nothing of interest here, unless someone wants old 9-track computer tapes and stuff like that. For what was lost, well that is true to a degree and 3 or 6 dB does not make that much difference at the other end, but I guess I am looking at the old Tucker rig and knowing its audio and RF power supplies are good for 3KW DC each. COL Tucker built it for military communications from Dallas to Austin. I mean, the thing was/is capable of who knows how much audio input on top of the KW DC. I'm thinking of the peak power. It just seems a shame to idle it out along the wireless in 2nd gear. The upside is that it will probably last forever. The status on that beast is that there is a parasitic oscillation in the final's grid circuit, between the 4-1000 control and screen grids, at about 140MHz. Plate tuning, current, and neuralization setting do not matter or vary much at all with this issue and the grid current and screen current interact alot. I found that a 50 ohm resistor in series with the grid helped. Maybe I need to increase that value or I don't know.. The screen grid is heavily bypassed directly at the G2 terminals on the socket, and an RF choke is optionally in series with the screen to the chassis connector to no effect. This oscillation happens no matter if the grid drive connector is shorted, open, or terminated, so this tells me it is in the control grid circuit somewhere. Nothing's been changed from the original design there, so it is further mysterious. Also, I need to rig a 220V 30A outlet and power cord for it. I keep popping the 120V breaker when running up the final and modulation sides together (the unit has two 120V plugs presently). As far as audio, I'm willing to help anyone who wants better quality sound from their AM rig. I'm not a great RF expert at all but I am OK with increasing the fidelity/reducing distortion in audio amps. At this moment I'm limited to NVIS type antennas, but I have a tower to put up. another project. I hope a tower will get me better shortwave listening due to a higher antenna (and give me a place to put a 6M beam for FM). Patrick From: Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Re: How can we rid the HF bands of AM ? /\/\ If there's an emergency, you -certainly- won't be totin' yer RCA BTA1R out to a tornado/hurricane/(un)natural disaster site to setup emergency communications... and the remote site surely doesn't lend itself well to the kind of power requirements needed by an AM transmitter of any heft. The way *I* see it, we only lost 500w. Run your AM rig at 500w DC input to the final, and let the audio fall where it may. Perhaps some of the guys on the air will get more interested in making their final more efficient - find better ways to modulate their rigs - get some of the trashier sounding rigs off the air, by -helping- that ham with working on -his- rig. Get the ol' commraderie going, again. I can build stuff... I just need to have someone around to talk to, joke with, laugh at.. er, with (hehe) .. I'm just not a good self-motivator. Besides, working a project together is what fosters friendships and forges bonds that keep you tied in a hobby together, for a lifetime. Speaking of which, Patrick... you ever get your General Class license? I can't -wait- to hear some of that Big Iron you've got up there, on the air. --- 73 = Best Regards, -Geoff/W5OMR
[AMRadio] Re: How can we rid the HF bands of AM ?
so... how do we get the old "KW Input" for AM back now? probably impossible.. :( Later, he was a strong defender of the 1990 AM power reduction, and typcially replied to objections from the amateur community by putting a spin on his response in such a manner to totally evade whatever issue was brought up.
Re: [AMRadio] info wanted on 4-400 linear amplifier
The Thunderbolt was easily driven to full input by 20 watts. I recall it was easy to tune and very sensitive due to grid drive. The grid was swamped as I recall, so it was also very stable. PJ -- the Johnson Thunderbolt is a AB2 amp that uses 4-400A's check out this amp i think you might like the layout it uses a roller inductor instead of a varicap. 73 Tony wa4jqs
[AMRadio] roundtable ettiquette
Is there anywhere printed the 'netiquette' type of rules for joining and leaving a voice communications (AM) round table? for instance, what is bad manners, what is good manners, how exactly it works, etc. Thanks, PJ
[AMRadio] RE: Petition Pending
Unless I have misunderstoof the document, the author has left out the Technician licensees completely. Also seems to have kicked novices with morse code off HF. PJ Pete -- I laughed out loud -- let me help you out: http://www.geocities.com/k3xf/Rver124F.pdf
Re: [AMRadio] Baxter gets it
I find it all very entertaining. Indeed, the requirements of his class of license do not keep the riffraff out. After what he does with a part of the spectrum that I would like to use but for one requirement, I hope they throw the book at him. One FCC term I see is "apparent liability" If it is merely apparent and the FCC does not accuse him of actual liability, why would he be motivated to pay a dime? And does the FCC have the authority and the power to actually "take" money from him? Just curious as to how these things play out. PJ
[AMRadio] sweeping the audio on TX test
The EQ for sale made me think of this: How many of us, when we tweek ye olde voice transmitter, sweep the entire audio spectrum (or as much as will fit through the iron) to check flatness of frequency response and audio distortion? To me, the audio part of the hobby is as important as the RF part. PJ
Re: [AMRadio] FS: Audio Equalizer $60
That is a bargain! 1/3 octave. Great for touching up the 16Hz domain for those occasions where there just happens to be some incidental pipe organ music playing in the next room. Seriously that is a real nice EQ, I have one very similar PJ. Good looking, nice sounding audio EQ for sale. Cost $149 new, still mint condx for $60. Here's what it looks like: http://www.wa3vjb.com/pics/PEQ-3300.jpg And here's the book at the factory website: http://www.phonic.com/help/download/openPDF.php?pdfFile=../../UsersManual/peq.zip Please consider? Thanks, Paul/VJB
Re: [AMRadio] Help Identify This Transformer and Choke
Here are the specs on the choke and transformer. some stupid thing called "sorbs" keeps trying to block my mail. Patrick Jankowiak wrote: T-20C56 Universal type choke inductance 4-10 Henries Rated DC current 300mA The PA-710 is possibly an older version of the CG-710 which is: commercial grade +/-1.5dB 40-10,000 cps audio output, 20 watts, push pull 41, 42, 47, 49, 7B5, 6AK6, 6K6GT primary 14K/20K secondary 500, 200, 16, 8, 5, 3, 1.5 ohms case RC100 (round can with square flange) Patrick From: David Hollander <[EMAIL PROTECTED]> Can't find these two in any of the references I have. Does anyone recognize these numbers? UTC Audio transformer - Type PA-710 Thordarson Choke - T20C56 Thanks, Dave N7RK
Re: [AMRadio] ricebox experiments
well I don't now, the one on evilbay ended at $325 and reseve not met. Maybe these still have alot of value, and you seen to have everything for yours, must have cost a fortune! Since I posted, I have been researching them, and indeed it seems like they are worth quite a bit, I must have gotten a fantastic deal on mine. PJ From: "Jim Wilhite" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] ricebox experiments To: "Discussion of AM Radio" Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Well Pat, money speaks. Wonder what my 430S with the 10 Hz., AM filter 500 Hz CW filter, FM board, AT 250 tuner, power supply, 150 KHz receiver mod and most of the updates done would bring? Mine isn't as pretty, it has been used mobile and I have the palm mic, MC 50 desk mic, mobile bracket and power cord plus the data cable between the AT 250 and radio, original owners manual, copy of the service manual, and brochure. It all works too. I can't believe it will bring much, but we will see. 73 Jim W5JO
Re: [AMRadio] ricebox experiments
Wow, these antiques must be going up in value! I only paid $200 for my 430S, and that included the power supply and manual! Maybe I got a super-good deal. Here's what I got from the "ebay prices realized" site: TS-430S samples 12 min $255.00 max $885.00 If it were not for the broken switch which is likely unobtanium, I might go for it, just to get the filter and then re-sell.. Notice how the guy with feedback zero is dogging the high bidder.. I often find this suspicious, especially when the item hits near its theoretical ebaisian value. I note he has done the 10Hz readout mod as well, very nice. I'll watch this and see. Thanks, PJ From: Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] ricebox experiments http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=40067&item=5763403628&rd=1&ssPageName=WDVW
[AMRadio] ricebox experiments
I figured out that if you take the Kenwood TS-430S and do the mods required for installation of the 6KHz wide the AM filer, but instead of installing the filter, you just leave the 680 ohm resistor across the in/out connections, what you get is a very wide AM passband.. excellent for listening to strong shortwave broadcast, but very wide indeed.. like 20-30KHz.. Still, it beats the narrow [EMAIL PROTECTED] / [EMAIL PROTECTED] SSB filter. I can't find the darn [EMAIL PROTECTED] / [EMAIL PROTECTED] 8831.5KHz-centered "YK-88A" AM filter anywhere! I need an YK-88A!! Or maybe I could build some kind of simple passband filter. It would not have to be perfect, or sharp, just 'something'. I think I miss my R-390. PJ
Re: [AMRadio] AM Amps
..~wa5bxo/asyam/Amplitude%20Modulation.htm The television visual carrier is amplitude modulated in such a way. The black parts of the picture, in which noise is most easily seen, are transmitted at the highest power, and the white portions are transmitted at the lowest power. Likewise the top peaks of the audio voice waveform do not contribute as much to inteligibility, but the bottom sections do, and so he has inverted the signal to place the part which is both more important and more succeptible to obfuscation by noise in a position such that it is transmitted at the higher power level. The higher carrier and higher average power is a byproduct of this. PJ
[AMRadio] IARC Hamfest -don't forget! Irving, TX
Show up and you might even meet ME PJ http://irvingarc.org/ Irving Amateur Radio Club, Inc. 50th Anniversary 1955-2005 3rd Annual HamFest 2005 Saturday – March 12, 2005 - 8am - 2pm Location: Betcha Bingo Hall, 2420 W. Irving Blvd. #125, Irving, TX 75061 Directions: State Hwy. 183 E/W @ Story Rd. exit - south to Irving Blvd - cross intersection southbound. Right behind Eckerd's Drugstore. Talk-In Freq: 146.72/12 (110.9) Advanced Admission Donation- $3.00 ** At the Door -$4.00 Advanced Table Donation - $8.00 ** At the Door - $10.00 !!! Inside only- No Tailgating !!! ARRL Sponsored VE Testing Door Prizes Lots of fun * For more information, contact: Coleta Taylor - [EMAIL PROTECTED] Bill Caldwell – [EMAIL PROTECTED] Irving Amateur Radio Club, Inc PO Box 15 Irving, TX 75015-
Re: [AMRadio] N3RHT Shack Update
3B28's have a sort of white glow in the gas, right?
[AMRadio] N3RHT Shack Update
I have the same phenomenon with the 872's or 575's (whichever happen to be installed) in a homebrew rig. 3 light but one is dark, and the phenomenon stays at that socket. No obvious other issues.. how curious. PJ From: "Merz Donald S" <[EMAIL PROTECTED]> Subject: [AMRadio] N3RHT Shack Update Just thought I'd post an update on recent activity here I have this homebrew transmitter (I didn't build it) that has a Globe King 500B RF deck (running a 4-400 in place of the 4-250) and the rest home made. It's in a 6 foot rack with PP 811A's for modulation. The rack was professionally re-painted in black powdercoat and it is the nicest looking rack I have ever seen. It has brackets to support each chassis, locking rear door and tapped bolt holes in the rack rails. Unfortunately, after doing such a nice job on the cosmetics, the builder seems to have gotten lost in the electronics. The AC wiring was a lamp cord disaster and had to be all ripped out. High voltage connectors were old-fashioned ceramic posts with standard hookup wire used to make HV connections. The speech amp had every manner of abominable construction practice on display. There was no push-to-talk. He did not bias the 811A's but instead ran the (separate) modulator supply on a Variac to keep the plate voltage in the 1200V region. The enamel on the variac's windings had turned purple--so it was obviously under some strain. The final plate volt meter was junk. All of that has now been undone, though there is still plenty to do. The rig is putting out 275 watts of glorious AM as of last night. The 4-400 is being run at 1800 volts--so it is loafing. The 2 supplies run two 3B28 rectifiers each. 3 of them run with no visible indication at all. You can't even see the filament. But one gets a dramatic glow under load. I have not seen this before--is that gas in the tube? I'm dumping the Variac and biasing the 811A's. But I haven't added the bias supply yet. I was running the 811A's on 1500 volts with zero bias last night with no apparent ill effects. But there's no reason to push them like that. My buddy Rich Sperling rebuilt the speech amp and did a great job. He added push to talk and some control wiring that will make the rig easy to use. So with any luck I should have the rig on the air sometime in April. This will be the highest power AM TX in my shack when it's done. 73, Don Merz, N3RHT
[AMRadio] RE: Jim's tvi problems
The red gow is not the "pilot lamp" on the pole pig, is it? Mine has one.
[AMRadio] FCC Chair Resigns
And I had to hear about it on Saturday Night Live..
RE: [AMRadio] Physical Reality of Sidebands
An interesting aside is that burst is a shade of green, and appears a somewhat sickly green at that. >The 8 cycle color burst is phase compared to a crystal oscillator in a phase locked loop.
Re: [AMRadio] AM Amps
In my National NCL-2000, I can run 200W carrier and 800W PEP, but I do not, as 8122's are costly and the NCL's blower is really too small. I usually do my testing at 100W carrier and 400W PEP. In that amp, tuned up properly for each of two carrier level cases (approximately): loaded for 800W PEP; 200W carrier = 600W dissipation, 800W input, 25% eff. loaded for 400W PEP; 100W carrier = 300W dissipation, 400W input, 25% eff. The loading is adjusted such that in each case, the amp can't put out more than about 20% over the desired PEP limit without clipping. This gives a much lighter load on the tubes when the unit is adjusted to run at a lower power. If the loading was not adjusted lighter for the lower power level, the amp would not reach its peak efficiency at the PEP level and dissipate substantially more than the necessary power. Loading lightly also requires a close eye on the screen current. Impending clipping is accompanied in that unit by a sharp rise in screen current on peaks. Testing was done with a sine wave in order to determine these values. There is no claim to how a voice signal will behave, but the claim is made for the relationship between 'adjustment of loading' and 'maximum power output utilized' having a direct relationship on overall efficiency during high levels of modulation. Since the blower in the amp is rather small, and mounted to suck air in from the bottom, I built a "wind chest" out of a 12" BUD rack with no lid, on which the amp sits. A dual 4x4" squirrel-cage blower from a mainframe rack is mounted in the wind chest and sucks air in the front and blows it up through the amp and keeps things so cool that you can touch the tubes after a full power test and not get burned. The power supply regulation on the NCL2000 is such that in AM use, 800W PEP is about all it will do cleanly. In SSB mode with low to moderate speech compression it will do more like 1200W PEP due to a lower overall power requirement.
[AMRadio] server offline
The usual server at 208.190.133.201 is down due to a disk failure. A temporary is online but the content is limited to only the 1959, 1943, and 1949 Sylvania tube manuals. We hope to have the transformer catalogs, other tube manuals, and related fun stuff back online as soon as the disk can be replaced, however, it is being considered to replace the single aging DEC Alphaserver 2000 with a VMS cluster. We will continue to use the OpenVMS operating system, the best operating system in the world, which, other than for hardware maintenance, has allowed the Alphaserver to operate for the last four years unattended with no crashes, memory leaks, reboots, software babysitting, or incidences of hacking. We apoligize for the incontinence. Patrick
Re: [AMRadio] Matching a 100 watt PA am to drive 833'S
Good points Geoff! Yes I suppose I should give code another try, but I have tried in earnest several times and, well I have problems with languages and ciphers. Never been able to learn any computer language, and my Spanish is nonexistant Donde estas el banjo?. I pass the written stuff just fine. Basically I have given up on code, and will just wait it out, or, when the rigs are ready, I can get a buddy over who has a better license and I can 'air out' the rigs. Really it's kind of silly, to me, to have to learn to use a digital code (Morse) in order to be allowed to use an analog computer (An AM transmitter).. :P Patrick From: Geoff <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Matching a 100 watt PA am to drive 833'S Patrick, with your collection of parts and transmitters, and knowlege of the same,it's a shame you're sitting there with a Technician class license. You need to put those rigs on the air. They're old enough. The need to be HEARD! :-) 73 = Best Regards, -Geoff/W5OMR (descrete transistors are -not- evil. Evilness lies in microprocessors!)
RE: [AMRadio] Matching a 100 watt PA am to drive 833'S
Better than installing or connecting an evil transistorized driver to it. He asked for suggestions on how to make it work, so the field is open. As to why, I can't say. No one said anything about drilling holes (mutilation) but hopefully that won't happen. Patrick -- From: "Donald Chester" <[EMAIL PROTECTED]> Subject: RE: [AMRadio] Matching a 100 watt PA am to drive 833'S I think it would be a terrible mistake to mutilate a high quality transmitter by going from a design as superbly engineered as the BC-1F, and converting it to something as jury-rigged as using a power transformer for a driver transformer, or one output transformer feeding a second reverse connected output transformer to feed the grids. Don K4KYV
[AMRadio] Matching a 100 watt PA am to drive 833'S
I'll take a very wild stab at it. From the RCA TT-4 handbook, the 833's at 3000VDC require 400V peak G-G volts, that is 242 V RMS. The drive is 20W. That makes the current 82 mA. That makes the impedance 2950 ohms G-G. If you have an old output transformer such as a 6K CT to 0-4-8-16 ohm type, and were to connect the transformer's 16 ohm winding to the 8 ohm winding on the power amp, then the secondary would look like 3000 ohms, close enough. You could also do a chinsel-cheeze method and use a dual-primary power transformer (120V each primary) set up for 240VCT, and with a secondary voltage of 12VAC. Use one with at least 5 amps rating on the 12v winding. Hook the 12VAC winding to the power amp's 8 ohm output. The series'd two 120V windings of the power transformer (240VCT) now looks like 3200 ohms, close enough. You might be surprised how good a power transformer can sound when operated far below its ratings. From: Don Moore R Moore <[EMAIL PROTECTED]> Subject: [AMRadio] Matching a 100 watt PA am to drive 833'S To: amradio@mailman.qth.net Cc: amradio@mailman.qth.net Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=us-ascii I have a older BC 1F series gates transmitter. I would like to do away with the 845 driver tubes and drive the 833's with a 100 watt PA amp. Does anybody have any Ideas what I would need to match the amp to the driver transformer of the 833's. Don Moore W5FFK
[AMRadio] time mag blasts hams
From the local club mailing list. Seems it is true. Guess they think we are all lunatic old men that spend too much time in the basement. (Myself, I'm not too old, nor do I have a basement) Tom NU4G This week's issue (December 27) has an article on "blogs" on page 109. In the article the following sentence will surely grab the attention of Ham Radio operators and stamp collectors - "Before this year, blogs were a curiosity, a cult phenomenon, a faintly embarrassing hobby on the order of HAM RADIO and stamp collecting." ]]] Letters to the editor can be sent to [EMAIL PROTECTED] Fuss at Time Magazine. Please pass this along to all of your ham buddies. Jess KR4OJ
[AMRadio] Happy Festivus!
Merry Christmas, Please find your 'presents' here: The 1940 RCA TT-3 Air-Cooled Transmitting Tube Manual http://208.190.133.201/rcatt3/index.html The 1937 Kenyon Amateur transmitter Manual http://208.190.133.201/old_iron/kenyon37/index.html Thanks to Steve Smith WB6TNL for sending me the Kenyon Manual! Best regards, Patrick Jankowiak KD5OEI
[AMRadio] Rothman Modulation
I would like to know more, here's all I ever found. -- From: [EMAIL PROTECTED] Subject: [AMRadio] AM space Hello All: It is my observation that there is a goodly amount of 'open' space from 14.3 to 14.35 MHz. most of the time. Conditions are not favorable as 75...but having ample 'elbow room' sure feels good. Would it be worthwhile to consider an AM gathering location there? PS: anyone familiar with Rothman AM modulation? Happy Holidays, Steve WA2TAK Mike Baker <[EMAIL PROTECTED]> wrote: Hello to all. When I was a kid I recall reading something in an old CQ/73/QST magazine about a modulation method for AM called Tayor Modulation. It was sort of a precursor to controlled carrier and used a seperate modulator tube hooked up sort of in parallel to the final amp and usually was the same tube type. There was no modulation transformer like in typical class B High level modulation schemes. Hi, Mike You are thinking of "Rothman Modulation" April 1952 CQ. (Which I can't find). If I recall correctly, controlled carrier screen voltage for the finals was derived from the rf output carrier power. I remember a picture of an outboard box with a couple of 6Y6 style tubes (perhaps it was a single 6Y6 and a rectifier tube), modulating a pair of 813's. 73, Ed Knobloch Article: 101890 of rec.radio.amateur.boatanchors From: "COLIN LAMB" <[EMAIL PROTECTED]> References: <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> Subject: Re: Info needed on "Taylor Modulation" from the 50's. Message-ID: <[EMAIL PROTECTED]> Date: Fri, 22 Oct 2004 18:05:19 GMT Hello Ed: My wife says I have so much crap I could not possibly find anything - but I walked right to the shelf where the April 1952 CQ magazine was. You are therefore batting 1 for 3, since you got it right on the outboard chassis, but wrong on the 6Y6 style tube. However, when you get to be our age and have forgotten more circuits than the younger hams have ever read about, that is not that bad. Anyway, there were two different circuits shown. A 100 watt mobile modulator using a 6X4 rf rectifier with a 6SN7 modulator tube, and a fixed station modulator for up to 1000 watts uisng an 80 rf rectifier, a 6SL7 speech amp and a 6CD6 modulator tube. Since the 6CD6 tube has a plate cap, it does not look like a 6Y6. The 6BQ6 and 6BG6 can also be used. I have a number of 6CD6 and 6BG6 tubes and never could figure out what to do with them. This is the answer. Build dozens of Rothman modulators. I think later that year and into 1953, you could buy an "efficiency Modulator" using this system. They claimed 70% efficiency, which was much better than the 52% efficiency of high level plate modulation. And my wife thinks I cannot find things. Ha. 73, Colin K7FM --
[AMRadio] Re: [Amps] Marconi AM Transmitter
Don't tear it up! Maybe someone on the MIL list might want to collect it. I posted it over there. Please don't part it out if it's complete.. - Original Message - From: Roger Parsons <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, December 20, 2004 5:44 AM Subject: [Amps] Marconi AM Transmitter >> A friend of mine (VE3AC) has an old (1952) Marconi >> 500W AM transmitter, which is ex Canadian military and >> covers 1.5-15MHz. It uses a pair of 4-125s in both PA >> and modulator. It is very nice, but also very heavy! >> >> Does anybody know if this is worth anything, or >> collectable, or would he be best to take it apart and >> sell the tubes/vacuum variable/transformers etc? >> >> Thanks >> 73 Roger >> VE3ZI
Re: [AMRadio] The AM Window
google search K1MAN.. Gee, I had no idea what a character this guy is. If he's really making these lengthy broadcasts and ranting on, etc.., then he's doing no more good than I was years ago when I used to have my weekly go at CB channel 30 with a pre-recorded 'program material' including music and old commercials from the '50's. At least my 'show' was entertaining -and it was not on the ham equivalent of 'channel 19'. Patrick Jankowiak Reformed CB nut
RE: [AMRadio] 3-500Z vs 4-400A
True, but the rig had a pair of 304TH's in it before, and is capable of running [EMAIL PROTECTED] CCS on both the modulator and PA HV supplies (separate and individually adjustable from 0-4000V), so I want to preserve the maker's intent by not downsizing the modulator tubes. The modulation transformer is from an RCA 1-K broadcast transmitter. It was built back in the "DC KW" days and has a special 'band' for 2726KHz, a Texas State Guard frequency. Durward Tucker W5VU spent 2 years building that 24x7 KW rig and I must avoid doing anything that would diminish its specifications, out of respect. There are no simple and inexpensive replacements for 304TH except 3-500Z or 4-400 (and blower). So many of the radiation cooled tubes like the beautiful 250TH are rare and costly, and I did not want to use 4CX250B's or smaller radiation cooled tubes, wanted to stay with large glass. Here's the rig's page, so you can see what I am trying to restore. In the Binder, there is a page showing 2160 watts tested as a DC input at carrier condition. There was no real power limit for the Guard's transmitters. http://208.190.133.201/tuckerkw/tucker_transmitter.html All I can say is that with today's restrictions on peak output power, the tubes in the rig will just idle along, and last forever.. Patrick -- From: "Jim candela" <[EMAIL PROTECTED]> Subject: RE: [AMRadio] 3-500Z vs 4-400A To: "Discussion of AM Radio" Patrick, For a "legal" AM plate modulated ham rig, running the tubes you mentioned as you mentioned is way over kill. Heck, ~ 300 watts or so of audio is all you will ever need to modulate the a rig designed for 375 watts carrier output. If I had 4-400's I'd go AB1 and run it as a tetrode. Sure, that requires a bias supply, and a screen supply. The drive will be simpler, and a lot less swing, enough simpler to justify the extra complexity of the extra power supplies. A 12AX7 driver would do fine. As for your question, yes it's workable. I would use negative feedback however to linearize those tubes a bit since distortion will be fairly high. The hardest part of your plan is getting undistorted drive from the driver. Maybe use one of your 2 X 8005 PA amplifiers driving a quality audio output transformer in reverse. Regards, Jim
Re: [AMRadio] 3-500Z vs 4-400A
It's to drive the screen grids, so since they run at 500VDC or more in AB1, it could reasonably take 1000V G2 to G2 to fully bring each tube to peak plate current. I think I read that the "120W 807's" needed about 400V G2 to G2. Patrick -- I just don't see a pair of ANYTHING as needing 1000 grid volts of drive in Amatuer service... or am I reading that wrong? --- Patrick said: Ok, in the name of versatility, suppose there's this simple transformer coupled push pull modulator chassis, set up for 4-400A's in class B. (yes but read on) In the chassis, the socket terminals which would go to the 4-400 control grids have a 20K resistor between them and the screen grid terminals. The idea is to limit the control grid current of the 4-400, and let most of the audio drive the screen grids. Kind of like the old 120W class B zero bias 807 modulator from the ARRL and RSGB handbooks. I won't nit pick about exactly what class it is, probably more like real-world AB2. Ok. so I drop in a pair of 3-500Z's. Of course the 20K resistors would not matter when the 3-500Z was inserted, as all 3 non-filament pins are connected to the triode's grid. I throw a DPDT switch, to change taps on the driver transformer from ones supplying 1000V peak grid to grid (to drive the screens of the 4-400's as triodes), to those taps supplying a lesser voltage appropriate for the 3-500Z's. -- Man, my 250TH's (triode), in Class B, only require around 400vpk g-g drive, for full output at 3kV. And 400vpk is a bunch for driving modulating tubes! 73 = Best Regards, -Geoff/W5OMR -
[AMRadio] Re: 3-500Z vs 4-400A
Bob, I agree, and although the unltralinears do sound good, I think that cathode feedback cures more sins of the output transformer, and does not rob power like the screen grid ultralinear setups seem to. it gets its extra voltage from the power supply and the tubes handle the extra current when needed. I think a good test of the effects are to pass a low frequency square wave. Like ultralinear it also needs a separate winding, but only capable of making a peak voltage equal to about half the peak grid voltage. Like the screen winding scenario, the correction to the cathode bucks the gain to a certain definite level when all is perfect (top of the square wave is perfectly horizontal), decreases it during time when the HF response through the transformer is too great (top of the square wave slopes up during the half cycle), and increases it during time when the LF response is poor (top of the square wave slopes down during the half cycle) such as when the transformer is deficient in iron. Did I explain this correctly? When the output waveform of the transformer does not match the input to the tube grids, the negative feedback to the cathodes corrects the instantaneous grid-cathode voltage with the goal of straightening up the tube-transformer combination to where it is very linear. Higher plate voltage helps this work better, and more grid drive voltage is needed, and if grid current is drawn, the driver must be exceptionally well regulated, and the power supply needs to have the capacity for high peak currents (alot of demands). A triangular wave is good for judging this. The straighter the lines of the triangle, the more linear the stage. I have a couple articles on doing this with old PA amps here: http://www.montagar.com/~patj/mi12188a.htm http://www.montagar.com/~patj/aph1050.htm (or at least the audio experimenters like them) Truthfully, with this mod, you can actually hear the difference, it will clear up a muddy old amp right quick. Maybe would be good for the speech amp. It also gives the amp very good regulation. On the APH-1050's, which have good iron, I was passing a 10Hz squarewave through two of them (one unmodified, one modified), and on the modded one, you could really hear the laminations go 'thunk' each time the polarity was reversed, and watch the plate voltage waveform greatly distort in order to cause the current through the transformer to remain true to the input signal. The unmodded one came nowhere close to faithfully reproducing a square at 10Hz. In the modded one, there was some ringing on the leading edges, but tuning the overall feedback loop capacitor's value minimized it. I had to ditch the 6L6's though and use 6CD6's so there would be plenty of current capability. The only issue with filament type tubes and this method is having to use a separate filament transformer for each tube in the PP pair. But back to the 4-400's since there may be questions about how the tubes would sound having the control grids driven along with the screens, maybe the other option would be to connect the grids to the center tap of the filament transformer for no drive, and just drive the screens with audio, like a zero bias triode setup. I have not decided exactly what to do for fidelity since I am set up for 3-500Z's right now. I may have to see if a speech amp modified for cathode feedback and greatly oversized will be capable of good regulation and 3-4 times the required power will do it, assuming I can place it inside an overall feedback loop from the modulated HV supply to the speech amp input. The original question came up as the 3-500 and 4-400 fit the same sockets and use the same filament supply. Patrick --- From: "Bob Bruhns" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] 3-500Z vs 4-400A Hi Pat, The 20K resistor idea was published in an old article on getting 120 watts from a pair of 807s, but I have been told it really didn't produce that much power, it did some really odd things at low audio levels, and it really didn't sound good. The idea about tying the control grid and screen of a 4-400 together and using it as a triode might be better, but I suspect that the 3-500 will be a better triode than a kludged 4-400. Tying the screen of a 4-400 to the plate will *drastically* reduce plate voltage limits, and plate current will be much lower at acceptable grid potentials (instantaneous E-grid *below* instantaneous E-plate) - so it would be impractical, because the power output capability would be massively reduced. To do ultra-linear right would require a separate, center-tapped screen winding on the mod transformer. I am in favor of the 4-400, but with active screen drive to improve linearity. Some kind of circuit could take instantaneous control-grid drive and produce a corrective pre-distortion to the screen voltage, aimed at making the grid-plate transfer as linear as possible, and making
[AMRadio] 3-500Z vs 4-400A
Ok, in the name of versatility, suppose there's this simple transformer coupled push pull modulator chassis, set up for 4-400A's in class B. (yes but read on) In the chassis, the socket terminals which would go to the 4-400 control grids have a 20K resistor between them and the screen grid terminals. The idea is to limit the control grid current of the 4-400, and let most of the audio drive the screen grids. Kind of like the old 120W class B zero bias 807 modulator from the ARRL and RSGB handbooks. I won't nit pick about exactly what class it is, probably more like real-world AB2. Ok. so I drop in a pair of 3-500Z's. Of course the 20K resistors would not matter when the 3-500Z was inserted, as all 3 non-filament pins are connected to the triode's grid. I throw a DPDT switch, to change taps on the driver transformer from ones supplying 1000V peak grid to grid (to drive the screens of the 4-400's as triodes), to those taps supplying a lesser voltage appropriate for the 3-500Z's. workable? Interesting? nuts? Best regards, Patrick
Re: [AMRadio] AM Usage with Linear AMPS
The plate efficiency at full output under practical conditionsis usually of the order of 50 to 65 per cent. With less than the full output, the efficiency is proportional to the driving voltage. When the signal to be amplified is a carrier wave modulated 100 per cent, the carrier amplitude is half the peak amplitude to be handled. The efficiency for the unmodulated wave is then half the maximum efficiency, or 25 to abour 32 per cent under ordinary conditions. The average efficiency of a linear amplifier used with amplitude-modulated waves is hence relatively low, because ordinarily the wave is fully modulated only a small part of the time; even when fully modulated, it is at or near the crest value for only a small fraction of the modulation cycle. The peak output power that can be developed by a tube operating as a linear amplifier is approximately the same as the power developed by the same tube in Class-C amplifier operation, or it may be slightly greater since the linear amplifier does not operate at peak level continuously. Since the peak power of a fully modulated wave is four times the carrier power, a tube used as a linear amplifier is capable of developing something between one-half and one-fourth as much carrier power as the output attainable from the same tube operated as a Class-C amplifier. -Terman A pair of 6146's operating at 600VDC put out 100 watts single tone. This is the maximum that amplifier would make. The current was about 260mA. peak/single tone: 600VDC * 260mA = 156 watts input. 100 out, 56 dissipation. 64% efficiency. Carrier conditions: 600VDC * 135mA = 81 watts input. 25 out, 56 dissipation. 31% efficiency. I realize this is pushing 6146's, better would have been 80 watts PEP and 20W carrier. The point is the efficiency as taken by meter readings. These values can probably be validated on a host of existing 2x 6146-equippped gear.
[AMRadio] Re: GB> Re: 10 meter AM
"the connection was refused when trying to connect to qsl.net" Hmm.. [EMAIL PROTECTED] wrote: By popular request... here's the schematic of the transmitter section of the homebrew10m AM rig I'm working on: http://www.qsl.net/wd8das/10mAMqrp.jpg Steve
[AMRadio] music to entertain
I'll confess. Many years ago in my partially misspent youth, long before I got a ham license, I had compiled a 90 minute tape of old music and '50's commericals (commercials found on discarded tapes from a broadcast station), and played this every sunday at noon on the CB channel 30 while I drank whiskey. I was near a highway and for an antenna I used the outer shield of the cable TV wire, which ran about 200' before it got to a place where there was a ground wire. I used a modified-for-fidelity Radio Shack TRC-458 Navaho base station (even with a 500 ohm balanced audio input) and a home made 100 watt PEP linear with a pair of 6146's and ran 20W carrier, and a home made antenna tuner got the current flowing into the cable's shield. I would sometimes start it running and, instead of drinking, go for a drive to see how far it would go and still sound good. I was getting about 10 miles and the audio quality was superb. Once, a neighbor asked me if I had ever heard music on the telephone. "Huh? never heard of such a thing, must be a wire crossed" was the reply to that one.. Occasionally, when I would get done, someone in DX land would say 'play some more' or "[EMAIL PROTECTED] why can't ya play something different!!" I suppose I am a redneck. HOO-Whee!! Those were some fun days. Had a souped up pontiac GTO and a betamax too. I niether get drunk (Come to Jesus) nor play music on the air (got ham ticket and swore to the Wouff Hong) any more. I am still interested in high fidelity, but I use a good dummy load when I play, and generally use specific waveforms and frequencies to make measurements. That base station's still around here somewhere, but it's been un-modified and adjusted back to factory specifications as it should be. It's a great SSB rig, as CB radios go. Catch ya on the flip flop, er.. 73, Patrick
Re: [AMRadio] K1MAN Enforcement and WINLINK
if you look up K1MAN on the arrl page, you find several articles about trouble with the fcc.
Re: [AMRadio] B&W 5100B Progress Update
Tom, Looks like you got it fixed. The way ham gear is (was/is?) sometimes made, things might have to be just right to get the specified performance. I don't know much about the B&W, but maybe without the original modulation transformer, ther match is not quite perfect, so therefore slightly less performance. I hate to suggest it, but if you run maybe 80 watts, how much modulation do you get? Just for curiosity, can you tell the parameters of the circuit if you have measured them? I'd be greatly interested in the numbers. Maybe something will suggest itself for imporvement under scrutiny if you want to go to the trouble of getting the data. AM mode carrier condition: -PA B+ volts -PA screen volts -PA Plate current -Power out -modulator plate current modulated conditions: (sinewave at maximum % obtainable without clipping in the modulator) -modulation % -PA B+ volts -PA Plate current -Modulator B+ volts -Modulator plate current -Modulator screen volts -Modulator bias volts -rms or average value of 120Hz ripple on B+ Physical: -Model # of replacement transformer -connections made for impedance selection -DC resistance and voltage of the entire B+ winding of the power transformer -DC resistance and value of any HV B+ choke -value of filter capacitance on B+ -rectifiers (two 5R4 I think you said?) Patrick From: "Tom Elmore" <[EMAIL PROTECTED]> Subject: [AMRadio] B&W 5100B Progress Update I finally had time this week to install the Stancor replacement modulation transformer for my B&W 5100B and have found a set of taps that work on both the primary and secondary windings. I can make full carrier output of at least 100 watts but the modulation is only making about 85 to 90 % before it starts to flatten out on the scope and distort. I have changed both the modulator and final set of tubes and still get about the same percentage of modulation. I was hoping to make at least 100% easily. Someone mentioned recently that this was a characteristic of this unit and I wonder if it's power supply limitations or some other factors. Thank You Tom Elmore KA1NVZ Anchorage, Alaska
Re: [AMRadio] B&W 5100B Modulation Update
What are the dimensions? 3 3/16" H by 2 5/8" W by 2 7/8" D = A-3891
[AMRadio] RE: B&W 5100B Modulation Update
My book online says that the A-3891 is a 15 watt transformer. Could you be overloading and saturating it to the point where it is no longer transferring power, but just eating it? Seems quite small for the application. http://208.190.133.201/old_iron/STANCOR_140H_MAY1948_WEB/015.jpg -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Elmore Sent: Wednesday, October 13, 2004 12:35 PM > >The original modulation transformer has been replaced with a Chicago Standard Transformer Corporation # A-3891. Thank You Tom Elmore KA1NVZ Anchorage Alaska
[AMRadio] Mod xmfr
I have no information on the 813's distortion when used that way. Have you found any curves showing the effect of screen voltage on plate current? The linearity of those would tell something. Alot of external things affect distortion, the modulation xfmr is real important. Patrick From: Brett gazdzinski <[EMAIL PROTECTED]> Subject: RE: [AMRadio] Mod xmfr One thing I don't like about doing different things with tubes is there is no real info on running 813's triode connected. What's the distortion values? I have a Gonset G76 that uses zero bias and drives the screen grid of a pair of 6dq6 tubes as modulators. I don't think its real clean. Brett N2DTS
Re: [AMRadio] Mod xmfr
Ahh yes. The class-B 813 modulator. Glad to see it! I'd like to comment about it from an audio standpoint as I have done this for audio with 807's. I don't know how tough the 813 control grids are. I would suggest using some resistors to limit the current to the modulators' control grids to about 15 mA average (suggested based on the class C conditions in the tube manual; 20K worked for for 807's but the drive voltage was much less). It is really the screen grids that must be driven to get the plate current up. The peak screen voltage may also be as much as 750 volts (1500 g-g) for the 813 (the same value as the G2 DCV would be if it were operating AB1). An old audio output transformer from a tube amplifier makes a good driver transformer because it will stand the voltage well. The author might have some suggestions too. Patrick From: "Jim Wilhite" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Mod xmfr Check here: http://www.amwindow.org/tech/htm/813/813.htm
[AMRadio] Mod xmfr?
For a close idea of the 813s' needs as far as using them for AM goes, have a look at the transmitting tube manual such as the RCA TT-4. Pick a set of data that gets you close to the RF output you desire. ++ For the PA, 1600VDC at 150mA per tube (300mA) provides 360 watts of carrier from 480 watts input. For the modulator operating AB1 at 1500VDC, a 9300 ohm P-P load is called for in order to get 260 watts output. The rule of thumb is that the modulator should be able to provide an amount of power equal to or greater than half the DC input to the RF PA stage. This rule if accurate for sinewave modulation and a condition of proper impedance matching. So, the modulator, operating at either 1500VDC, or 1600VDC just like the PA, would have more than enough power for the rule. (RF PA 480 watts DC input /2 = 240 watts, and the modulator makes 260 watts) Just barely!! and you might lose a bit in the modulation transformer, but it will still be OK for the sinewave operation. Voice is not a sinewave, so it is useful to either make use of speech processing, or make the modulator able to put out twice or more of what the rule of thumb gives, if you can get away with it. That is another topic, and does not really reflect upon the impedance choices. ++ Next, what is the secondary impedance of the modulation transformer? It is the E/I of the RF PA stage, so that it is in the example 1600/0.3 = 5333 ohms. The modulation transformer could have an impedance ration of: 9300 to 5333 = 1.74 to 1 The turns ratio (voltage ratio) is the square root of that: SQRT 1.74 = 1.32 to 1 ++ 813's can put out more power operated class AB2. 813's as a modulator might be better somehow triode connected (G1 through 20K to G2 and drive G2) and operated closer to class B. I don't have any data for that but I would like to see it discused if anyone has done it.
[AMRadio] 10m AM anyone?
I'd like that amp, it would go well with the Sonar -23 I have. I don't think any mods were needed for 10M. Patrick From: "Brian Carling" <[EMAIL PROTECTED]> Subject: [AMRadio] 10m AM anyone? I have a Sonar CB amp here that uses a pair of rugged 6JE6 sweep tubes, that would make an ideal candidate for 10m conversion since it is tunable and would probably go to 28 MHz as-is with no problem. Anyone interested in it for your 10m AM station?
[AMRadio] SpaceShip One uses AM
Nitrous oxide is a powerful oxidizer. During ancient times when you could buy the stuff and nobody knew it was dangerous (and before sulphur dioxide was added in order to melt the lungs of anyone who 'gasses up'), I won many a bet, that I could burn a hole in an aluminum pie plate with a cigarette. 0. light cigarette (use a marlboro red or 100 with no holes in filter). 1. inhale nitrous 2. with cigarrette in mouth, bring pie plate up to coal. 3. exhale slowly through cigarette, turning its tip into a white hot torch. (haste wastes nitrous, sloth decreases temperature) 4. burn through the plate. the aluminum is consumed to ash. quite safe actually, unless you count the intoxication factor. The crazy stuff of the past.. whew. makes me wonder how I survived, stayed out of jail, and became successful. In any case, there's your field expedient torch. === From: [EMAIL PROTECTED] And the fuel is the reaction of rubber and nitrous oxide.
[AMRadio] ugly RBB cabinet wanted
Does not have to be pretty, but I would like one for my RBB prototype. Here's the rig.. http://208.190.133.201/vrps200309/vrps_swap_200309.html Patrick
[AMRadio] Re: AMRadio Digest, Vol 9, Issue 6
Jim, As a hi-fi amp, it is extremely clean and very flat from 20Hz to 20KHz up to about 80-100 watts. Above that, despite what the specs may say, heavy bass causes distortion due to the smallish size of the output transformer. As the point is approached, hum increases due to the transformer saturating. It is a first rate public address amp and a super modulator. I have looked into getting (having made) larger transformers to hadle 20-20K at 200W, but finding one with a 6500 ohm CT primary that will take the 930 volts DC is difficult. If I were to have them made, I would go for a 10K or 12K primary and change the power supply to solid state, add about 200uF of capacitors (mount where the 5R4's are), and eliminate the choke input (and the choke, to make room for the big transformer) for 1100-1200V on the plates. I have been quoted $400 each for such. I did experiment, simply bypassing the choke to get higher volts on the tubes, and got 240 watts, but the 'KLIXON' popped after a couple minutes, not from heat, but it also responds to current. I would not run them that way unless replacing the OPT's. I have only three, one is reserved for parts but is actually in working order less perhaps the tubes. Patrick From: "Jim candela" <[EMAIL PROTECTED]> Subject: RE: [AMRadio] Home brew AM Patrick, That Altec amplifier sure is nice! I really like the 5R4 full wave bridge rectifier with the extra filament taps off the HV windings. Never seen that done before. Also the 6W6 triode connected cathode follower stage is unique with the center tapped choke. I see negative feedback from the output tranny all the way back to the first preamp stage. Without getting too far into audio jargon, how do two of these beasts sound as a stereo amplifier? The HV filter only has 6 uf as part of a LC filter, so how is the bass response? Got a few dozen of these lying around? :) Regards, Jim Candela WD5JKO
RE: [AMRadio] BTA-250 and 1-K schematic
It does suggest: NOTE: some web browsers don't want to display a picture this size. Might be best to download it. so, right click and save as or save target as, etc.. then use a viewer. I could do a PDF I suppose. but it's a half meg file, so please allow a few seconds to save. Patrick
Re: [AMRadio] BTA-250 and 1-K schematic
It's there. My website is unfortunately very popular and I have but an ADSL line at 384K, so sometimes if someone's sucking down a huge document, things can time out for others. I wish I had a hardware fix to equalize all visitor's bandwidths. >> http://208.190.133.201/bta250/schem.html >> Patrick, When I go to this site I dont get anything. Is it still there? thanks Don
Re: [AMRadio] Home brew AM
I would say that the fidelity was pretty good compared to a BC-610, mostly because the audio amplifier was of exceptional quality and so lightly loaded. The power at carrier was pretty low, only about 80 watts, and when we were done tweeking, we were getting about a 340 watt PEP signal out of it. Running the power low, with low voltage and current allowed the rare tube to stay cool. As for power, I imagine the BC-610's carrier is much more powerful. The modulator amplifier is rated at 175 watts and is an Altec 1570B, using two 811A's in class B push pull with the grids driven directly from cathodes of some beam power tubes, the schematic of this unit is here: http://www.soundpractices.com/altec.html It has 10 tubes, and operates with 930VDC on the 811A's. I use two of these amps in my stereo. best regards, Patrick From: "Brian Carling" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Home brew AM How does that compare to the performance of say the 250TH final stage in a BC-610? It sounds like you are running at lower power. Also how many tubes do you use in the cathode modulator? On 2 Oct 2004 at 20:12, Patrick Jankowiak wrote: >> Cathode mod works very well on a 250TH. We are getting 80-90 >> watts carrier no problem at 2200V. For the details: >> >> http://www.montagar.com/~patj/cathmod01.htm >> >> >> Patrick
Re: [AMRadio] Home brew AM
Cathode mod works very well on a 250TH. We are getting 80-90 watts carrier no problem at 2200V. For the details: http://www.montagar.com/~patj/cathmod01.htm Patrick
[AMRadio] critical inductance or load current as you please
A little simulation here, showing what happens to a power supply's output from near zero to a bit of overload, to focus on the area where the "bleeder" or load current becomes high enough to meet with the 'critical inductance' value of the choke at hand. It makes a good case for a stout bleed. I hope it is interesting. http://208.190.133.201/bridge1.pdf A simulated power supply made from a 3500V transformer with 240 ohm impedance, a mercury vapor bridge rectifier, 15H choke, 40uF capacitor. Different loads were applied and the voltage/current data taken. A set of charts were made in excel to illustrate the behavior. 73 Patrick
[AMRadio] Re: Frequency Response
Sorry for the long winded post, but here it is.. Since the discussion is regarding distortion and frequency response, I would like to share some experience I have had with improving the fidelity of otherwise mundane audio power amplifers. Although some of the technicques presented may require some ingenuity to apply to a very large plate modulator, I feel that they have worthwhile and audible merit from the standpoint of linearity, 'tilt', and transient response. In the second case presented below, A/B tests with various CD recorded music including violin, Cuban percussion, and industrial styles, the improvements were very noticeable. Surely there is then merit for the improvement of the fidelity of the voice waveform. I would also like to suggest that a triangular wave is an excellent way to check the linearity of an audio amplifier. The proper circuit configuration around the phase inverter can make the sides of the wave obey an extremely straight 45 degree angle, to the point where the input and output signal shapes are nearly indistinguishable. 'Tuning' is done by superimposing the input and output signals on a scope and matching them. (In an amplifier with poor linearity, the sides of the triangle wave can 'bellow' out, or 'hourglass' in, just like the trapezoid RF waveform in a poorly designed or operated linear amplifier (go figure).) The first two circuits embody this method in the phase inverter circuit. I realize that many people may prefer a balanced circuit throughout, but it may not always be practical. The first two circuits also embody a cathode feedback scheme surrounding only the output tubes and the audio output transformer. This application will 'straighen up' and otherwise poor transformer quite well, although there are requirements for plenty of grid drive voltage and ample B+ voltage along with a large value filter capacitor on the plate supply. If the transformer is too small, the low frequency power output fidelity will be less improved since the transformer cannot handle the extra current demanded when correction takes place. A solution is to demand less power. This article describes the conversion of a fairly poor performing (actually bad sounding) 70W theater amplifier which suffers from lack of iron. The result is a very clear 40 watt amplifier. A method of in-circuit measurement of tube matching is shown. http://www.montagar.com/~patj/mi12188a.htm This article describes the improvements made to a decent-sounding 50 watt public address amplifier to the point where it is as faithful as a Quad or McIntosh as far as most people's ears are concerned. About 50 watts was still obtained (large iron). http://www.montagar.com/~patj/aph1050.htm This article demonstrates a method of coupling the output signal back to the grids around a transformer coupled high power (50 watt) AB2 audio stage. http://www.montagar.com/~patj/tubeart.htm For those interested in a QRP experience, this article describes an extremely linear series modulator for an 807 RF stage. http://www.montagar.com/~patj/amxmtr_dc_classamod.html Patrick
