Re: [AMRadio] Thordarson transformer question
In a message dated 12/30/03 3:48:15 PM, [EMAIL PROTECTED] writes: I think its just a banana plug connection. Thats what my 11M77 250 watt model uses in my homebrew 813 rig. Interesting My T11M74 40 watt unit would require a connector somewhat smaller than a standard bananna plug. Dennis D. W7QHO Glendale, CA --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html ---
RE: [AMRadio] Thordarson transformer question
Thordarson used some type of push pins, they came with the iron. I had a BIG mod transformer, the T-11m78 that had screw terminals, I used it in the 30K-1, and it went with it when I sold it. I have the same transformer with the push pins, its much smaller, has rounded sides, push pins on the side. Must have been a change, the older ones having the terminals? The T-11M78 worked very well in the 30K-1, at 2500 volts. Sounded quite good to me. I have not looked at it, but its likely possible to change out the push pins, by replacing the entire insulators, or adding a screw through each push pin with nuts, lock washers, etc. I have some of the push pins, but you need quite a few in some configurations, my pair of 4D32 transmitter will be low impedance, and need to parallel up both the primary and secondary, lots of push pins! The new project (4D32 rig) has changed from a transceiver to the worlds largest and most complex 200 watt AM transmitter, with separate decks for rf, rf control, modulator, power supplies (one for modulator, one for RF, with variac), and eventually, a home brew VFO/exciter. The thordarson mod transformer will go into it. I will need to experiment with it, the 4D32 tubes can run with higher voltages, 1000 volts I have been told. At 600/700 volts, the power output should be 200 watts, who knows with 1000 volts on the plates. Ray tells me the article on the second home brew receiver will start in the January issue of Electric Radio. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Todd Bigelow - PS Sent: Tuesday, December 30, 2003 6:32 PM To: AMRadio@mailman.qth.net Subject: [AMRadio] Thordarson transformer question Thanks to the link that Pete posted earlier, I found the information on a mod transformer found at a hamfest a few years back. It's a Thordarson Multi-Match model T-11M78, 300-500 watt model. Something puzzles me, though - in the listing information it says Features Thordarson Switchboard Plug-in Terminal Board for quick and accurate matching of tube loads. Now, I noticed that the terminals didn't have a typical threaded screw hole or post like most others, but I have no idea what kind of 'plug-in' plugs it uses. Is there anyone out there who could shed some light on this matter for me? Many thanks - Todd, KA1KAQ ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] Thordarson transformer question
I stand corrected. Now that you mentioned it I agree the holes are smaller than the standard banana plug, however, it is a push in plug so finding the correct diameter is the only problem. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Tuesday, December 30, 2003 10:33 PM To: [EMAIL PROTECTED]; amradio@mailman.qth.net Subject: Re: [AMRadio] Thordarson transformer question In a message dated 12/30/03 3:48:15 PM, [EMAIL PROTECTED] writes: I think its just a banana plug connection. Thats what my 11M77 250 watt model uses in my homebrew 813 rig. Interesting My T11M74 40 watt unit would require a connector somewhat smaller than a standard bananna plug. Dennis D. W7QHO Glendale, CA --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Thordarson transformer question
Brett Gazdzinski wrote: Thordarson used some type of push pins, they came with the iron. I had a BIG mod transformer, the T-11m78 that had screw terminals, I used it in the 30K-1, and it went with it when I sold it. I have the same transformer with the push pins, its much smaller, has rounded sides, push pins on the side. Must have been a change, the older ones having the terminals? Okay, this makes sense. Mine is the one with the rounded corners, wrinkle paint on the end bells. Nice nickel-plated 'acorn' cap nuts on the ends. The openings look too small for a banana plug but they definitely don't looked threaded either. What do these push pins look like and does anyone have a picture or know of a site that shows them? I don't recall seeing anything anywhere here that would work, but they could be in a parts drawer or box full of 'stuff' and without knowing what to look for, I could pass them over easily (I have a lot of 'stuff'). The T-11M78 worked very well in the 30K-1, at 2500 volts. Sounded quite good to me. This one is about the size, maybe a bit larger than the plate transformer in my 30K-5, the side tag says 300-500 watts. I have not looked at it, but its likely possible to change out the push pins, by replacing the entire insulators, or adding a screw through each push pin with nuts, lock washers, etc. Looks like you'd have to pull the entire side panel off and replace the insulators as one unit on this one, but I could be wrong. One could probably stuff large diameter, stiff wire into the holes too, but I'd like to do it as close to 'right' as possible. I have some of the push pins, but you need quite a few in some configurations, my pair of 4D32 transmitter will be low impedance, and need to parallel up both the primary and secondary, lots of push pins! Sounds like these pins must have a hollow head, allowing you to stuff one inside another to double things up? This one has 6 insulators down each side, and the holes are maybe 2-3 times the diameter of a pencil lead. Physically it appears to be the same size as the mod transformer for the 300G, with more connections. But I'm assuming that since the mod transformer for the 300G was a specific unit (instead of multi-match), it required fewer connection points and used studs instead of push pins. The opening for those push pins looks wimpy as all hell compared to the studs. ~ Todd KA1KAQ
RE: [AMRadio] Thordarson transformer question
Something puzzles me, though - in the listing information it says Features Thordarson Switchboard Plug-in Terminal Board for quick and accurate matching of tube loads. Now, I noticed that the terminals didn't have a typical threaded screw hole or post like most others, but I have no idea what kind of 'plug-in' plugs it uses. Is there anyone out there who could shed some light on this matter for me? They take a smooth pin, similar to the filament pin on a 4-pin tube socket. I don't think standard size banana plugs work. Special plugs came with the transformers. Lacking the plugs, try various sizes of large gauge copper wire, or small diameter brass rod stock from the hardware store. You might even experiment with pins removed from (defunct) tubes if you have any lying around. The pin should plug in with a snug fit, but not be forced in. Once you figure out the optimum size, it shouldn't be difficult to come up with something to make a set of homebrew plugs. Don K4KYV _ Tired of slow downloads? Compare online deals from your local high-speed providers now. https://broadband.msn.com
Re: [AMRadio] Thordarson transformer question
Mine is the one with the rounded corners, wrinkle paint on the end bells. Nice nickel-plated 'acorn' cap nuts on the ends. The openings look too small for a banana plug but they definitely don't looked threaded either. What do these push pins look like and does anyone have a picture or know of a site that shows them? As I recall, the stock pins are mounted on little round plastic (bakelite?) discs that attach to the connecting wire. I have not looked at it, but its likely possible to change out the push pins, by replacing the entire insulators, or adding a screw through each push pin with nuts, lock washers, etc. Looks like you'd have to pull the entire side panel off and replace the insulators as one unit on this one It would be a shame to ruin a vintage unit like that. Those things are classics. Another problem, some of them are potted with tar. You would have to heat the whole transformer to melt the tar in order to disengage the side panel to get at the receptacles. That would be messy, as best, and at worse, you could damage or ruin the transformer in the process. I have some of the push pins, but you need quite a few in some configurations... ... One could probably stuff large diameter, stiff wire into the holes too... That would be the best bet until you can find some proper pins. Murphy says that if you successfully modify the transformer, you will find a set of real push-pin plugs at the next hamfest. but I'd like to do it as close to 'right' as possible. I'd stay away from doing anything to modify the original transformer. Don K4KYV _ Expand your wine savvy and get some great new recipes at MSN Wine. http://wine.msn.com
Re: [AMRadio] Thordarson transformer question
What's the OD and length of the pins you need? There's probably something around that someone will know of that's very close if you can measure the ones you've got - when I couldn't find pins for my Johnson swr bridge, it turned out that normal bananas with the flat blades removed yielded pins of the correct OD (better lucky than smart, probably better both). Alternatively, round brass stock from the hobby/hardware shop is easy to work with, and probably comes in a size very close to the right OD as well. Another thought - something I have done more than once. If stock round brass rods are slightly too large and you don't have a metal lathe, you can jury rig a lathe by chucking the rod in a small high-speed electric drill. Hold a fine-tooth flat file against the rod and switch on the drill. You can easily dress the rod, taking off a mill or two of diameter in a very short time. With a little care and patience you can end up with a uniform diameter exactly the size you need. Just keep testing by seeing how easily it inserts into the receptacles until you can get a snug fit that doesn't require forcefully jamming it into place. I once made a slightly oversize nominal size shaft precisely fit a dial bushing that way. You can fine tune, using emory cloth or sandpaper once you get close using the file. Of course a real lathe and knowledge of how to use it would be much better. Don k4kyv _ Have fun customizing MSN Messenger learn how here! http://www.msnmessenger-download.com/tracking/reach_customize
Re: [AMRadio] Thordarson transformer question
Donald Chester wrote: snip It would be a shame to ruin a vintage unit like that. Those things are classics. Another problem, some of them are potted with tar. You would have to heat the whole transformer to melt the tar in order to disengage the side panel to get at the receptacles. That would be messy, as best, and at worse, you could damage or ruin the transformer in the process. I'd stay away from doing anything to modify the original transformer. Don K4KYV Don and group: I agree completely. This transformer itself could be a work of art just in the design, paint, and attention given to details like the cap nuts. The insulators are a deep brown porcelain with a wonderful shine, like new. I've had this unit for about a decade, having purchased it at a hamfest for $10 from a university that was cleaning house. My biggest concern was using it somewhere in a rig where I'd never see it! It looks that good. It didn't come with pins though, and since all the iron I've come into contact with either had studs or wires, I'm just at a loss for what these pins look like. But you can rest assured, I'm not about to do anything to modify this unit to simplify its use. I have enough stuff around here to muck with as it is. I wouldn't mind using stiff wire temporarily, but I'd prefer to use the correct hardware if possible. Out in my garage there is also a HUGE power supply purchased from a friend mainly to obtain the large UTC (I think) HV transformer in it. It's close to 3 feet long and a foot high inside of a footlocker-sized rolling cabinet with a clear plexiglass end, and took 3 of us to roll it up into a pickup. It's not as 'finished' looking as the Thordarson mod iron, but it's not bad looking. Someday , given enough time and enough floor space, they'd be the makings of a great HB rig. Not sure how to put a viewing window in that far down the cabinet, though. ~ Todd KA1KAQ
Re: [AMRadio] Thordarson transformer question
[EMAIL PROTECTED] wrote: What's the OD and length of the pins you need? There's probably something around that someone will know of that's very close if you can measure the ones you've got Scott - No idea what I'm looking for, the insulators stick out about half an inch and a jeweler's screwdriver will slide in about 3/4 inch. For all I know, there may be something similar to what came with it lurking in a box around here somewhere. The only thing that comes to mind are the old 'phone tip/pin' plugs on early headsets. Something along those lines I'm guessing? ~ Todd KA1KAQ
RE: [AMRadio] Thordarson transformer question
I think its just a banana plug connection. Thats what my 11M77 250 watt model uses in my homebrew 813 rig. Mike W0FD -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Todd Bigelow - PS Sent: Tuesday, December 30, 2003 4:32 PM To: AMRadio@mailman.qth.net Subject: [AMRadio] Thordarson transformer question Thanks to the link that Pete posted earlier, I found the information on a mod transformer found at a hamfest a few years back. It's a Thordarson Multi-Match model T-11M78, 300-500 watt model. Something puzzles me, though - in the listing information it says Features Thordarson Switchboard Plug-in Terminal Board for quick and accurate matching of tube loads. Now, I noticed that the terminals didn't have a typical threaded screw hole or post like most others, but I have no idea what kind of 'plug-in' plugs it uses. Is there anyone out there who could shed some light on this matter for me? Many thanks - Todd, KA1KAQ ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
