Re: [AMRadio] Need advice on storing RF power tubes
Thanks, Todd for all that good information. Yes, let us try a sked sometime on 40 meters. All my best. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: "Todd Bigelow - PS" <[EMAIL PROTECTED]> To: Sent: Wednesday, December 31, 2003 8:28 PM Subject: Re: [AMRadio] Need advice on storing RF power tubes > David Knepper wrote: > > >Todd, you have to be very careful when removing those 75TH tubes, which were > >the original types used in the 30K-1. > > > Uh huh, *now* ya tell me. Actually I broke it a few years back when > simply trying to remove it so I could restore the mod deck. It made me > wanna puke when I realized what just happened, so I stuffed it back into > the chassis and shut the door for a while. Finally found a pair of > replacements back in May. > > >What you need are adapters that slip over the grid pins. These were made by > >Eimac to be used with any of these tubes that had that pin arrangement. > >These caps slipped over the pins and were much more sturdy than the grid > >pins. > > > > > > Well, that was the problem: these caps are some kinda weird, they split > down the center and are held together under pressure on the pin not by > ONE snap ring on top, but also by another beneath it. I'd never seen > them before so I was trying to get the tube out to where I could eyeball > it better. Those snap rings require goofy pliers to remove them, and > it's not the type of thing for the faint of heart to attempt by reaching > under the cap with a mm or less of clearence between the cap and the top > of the glass envelope. > > Today I did the smart thing. After removing the tubes last night with > plate caps and wires still attached (I removed them at the ceramic posts > on the chassis), off we went to see my friend Ray, KC1BT who is a former > BC engineer and has seen, made, and repaired at least one of everything. > He'd never seen this type of cap before either, but his pliers are a lot > better than mine so we prevailed. It was actually easier to slide the > cap off the intact tube with only the top snap clip removed since the > envelope held the pin in place firmly (unlike the one I broke). > > So...now they're sitting in the radio room, waiting to be installed > later tonight. The next step is obtain a crystal for 40M AM and > hopefully to locate the plug in inductor cans for the oscillator and > multiplier plate circuits in the 75M band. The mod 5 differs from the > ham version in that it has two switchable crystal controlled frequencies > with complete tank circuits which each require a combination of 4 coils. > My rig came set up for 6-8 Mcs and 2 - 3.4. Would be nice to find a > complete coil set along with a 310C-2 vfo unit. I traded for a 310B-2, > only to find out it was the wrong unit for my transmitter. Maybe someday > we can work on 40? > > 73, Todd KA1KAQ > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Need advice on storing RF power tubes
David Knepper wrote: Todd, you have to be very careful when removing those 75TH tubes, which were the original types used in the 30K-1. Uh huh, *now* ya tell me. Actually I broke it a few years back when simply trying to remove it so I could restore the mod deck. It made me wanna puke when I realized what just happened, so I stuffed it back into the chassis and shut the door for a while. Finally found a pair of replacements back in May. What you need are adapters that slip over the grid pins. These were made by Eimac to be used with any of these tubes that had that pin arrangement. These caps slipped over the pins and were much more sturdy than the grid pins. Well, that was the problem: these caps are some kinda weird, they split down the center and are held together under pressure on the pin not by ONE snap ring on top, but also by another beneath it. I'd never seen them before so I was trying to get the tube out to where I could eyeball it better. Those snap rings require goofy pliers to remove them, and it's not the type of thing for the faint of heart to attempt by reaching under the cap with a mm or less of clearence between the cap and the top of the glass envelope. Today I did the smart thing. After removing the tubes last night with plate caps and wires still attached (I removed them at the ceramic posts on the chassis), off we went to see my friend Ray, KC1BT who is a former BC engineer and has seen, made, and repaired at least one of everything. He'd never seen this type of cap before either, but his pliers are a lot better than mine so we prevailed. It was actually easier to slide the cap off the intact tube with only the top snap clip removed since the envelope held the pin in place firmly (unlike the one I broke). So...now they're sitting in the radio room, waiting to be installed later tonight. The next step is obtain a crystal for 40M AM and hopefully to locate the plug in inductor cans for the oscillator and multiplier plate circuits in the 75M band. The mod 5 differs from the ham version in that it has two switchable crystal controlled frequencies with complete tank circuits which each require a combination of 4 coils. My rig came set up for 6-8 Mcs and 2 - 3.4. Would be nice to find a complete coil set along with a 310C-2 vfo unit. I traded for a 310B-2, only to find out it was the wrong unit for my transmitter. Maybe someday we can work on 40? 73, 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? How about on the old early commercial VHF radios, that had the transmitter in the rear of the vehicle, and the control head in the front? The pins that went in the back of some of those early models (I'm thinking Federal, or early GE) had pins that fit into about the same sized hole... 73 = Best Regards, -Geoff/W5OMR (oh yeah - by the way "Happy New Year" ;->) -- 7:07pm up 7:50, 5 users, load average: 0.16, 0.08, 0.04
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
Donald Chester wrote: 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
They look quite like octal tube socket pins, but have a black plastic bit on the end the wire comes out of. You solder the wires onto the pins, like you would to a tube base type plug. You can likely use tube base pins, but I don't like connections that are not secure... Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Todd Bigelow - PS > Sent: Wednesday, December 31, 2003 12:10 PM > To: amradio@mailman.qth.net > Subject: 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 > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Thordarson transformer question
In a message dated 12/31/03 9:52:01 AM, [EMAIL PROTECTED] writes (in part): > They take a smooth pin, similar to the filament pin on a 4-pin tube > socket. > Yep, they sure do. Went back and took a look at another T11M74 in and old Grazing Service rig which is hooked up with the origianl plugs. Took a close look at the transormer and see that the little sockets are split and spring apart slightly when the plug is inserted to insure a good tight connection. Turns out a 6-32 screw is just the right size to do the same thing and gives a nice snug fit. So, there's a good substitute for the original pins. 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
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
[AMRadio] One Hell of a Hamshack
Hi guys: If you are in need of a hamshack complete with radar, here is your chance. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2450501898 Have fun bidding. 73 Jim de W5JO
Re: [AMRadio] Need advice on storing RF power tubes
Todd, you have to be very careful when removing those 75TH tubes, which were the original types used in the 30K-1. What you need are adapters that slip over the grid pins. These were made by Eimac to be used with any of these tubes that had that pin arrangement. These caps slipped over the pins and were much more sturdy than the grid pins. All my best. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: "Todd Bigelow - PS" <[EMAIL PROTECTED]> To: Sent: Wednesday, December 31, 2003 12:20 PM Subject: Re: [AMRadio] Need advice on storing RF power tubes > David Knepper wrote: > > >I wished that I had used spell check on my post. > > > >"attempting" and "during" > > > >In my humble opinion, the reason for the filament to shatter, break, snap, > >open, split; crack, divides, etc. or whatever occurs is physical jarring. > > > > I'd agree with this. And as Geoff pointed out, sagging over time if > stored incorrectly could be a problem too. I have an old 250TL still in > its metal shipping frame, hanging upside down but vertically, suspended > by springs. Amazing what they used for packaging back then! > > >However, I had a gentleman in New Zealand ship me two 75TH tubes for my > >30K-1 and they arrived in great shape. Think of how many "frequent-flyer > >miles" these tubes had since leaving the factory in California. > > > > Indeed. I'd be curious Dave, to hear what kind of plate cap arrangement > yours use. I broke one on the mod 5 by trying to take it out of the base > and slip it out where I could get to the cap. Someone came up with a > split-cap design held in place by two of those ring clips requiring > special pliers to remove. Just the slight amount of torque from lifting > the tube out of the socket *slightly* was enough to cause the top seal > the break. Found a pair last spring at a hamfest, after looking for a > couple of years. Also, I thought the 30K-1 used 75TLs, or was that just > 'early design' and production ended up going with the TH? > > ~ Todd KA1KAQ > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
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. I agree with Don, It'd be a shame to monkey with the transformer. Good Luck! 73, Scott --- 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
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
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] Need advice on storing RF power tubes
David Knepper wrote: I wished that I had used spell check on my post. "attempting" and "during" In my humble opinion, the reason for the filament to shatter, break, snap, open, split; crack, divides, etc. or whatever occurs is physical jarring. I'd agree with this. And as Geoff pointed out, sagging over time if stored incorrectly could be a problem too. I have an old 250TL still in its metal shipping frame, hanging upside down but vertically, suspended by springs. Amazing what they used for packaging back then! However, I had a gentleman in New Zealand ship me two 75TH tubes for my 30K-1 and they arrived in great shape. Think of how many "frequent-flyer miles" these tubes had since leaving the factory in California. Indeed. I'd be curious Dave, to hear what kind of plate cap arrangement yours use. I broke one on the mod 5 by trying to take it out of the base and slip it out where I could get to the cap. Someone came up with a split-cap design held in place by two of those ring clips requiring special pliers to remove. Just the slight amount of torque from lifting the tube out of the socket *slightly* was enough to cause the top seal the break. Found a pair last spring at a hamfest, after looking for a couple of years. Also, I thought the 30K-1 used 75TLs, or was that just 'early design' and production ended up going with the TH? ~ Todd KA1KAQ
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] another SX-28 question
its an old age thing!! -- Original Message --- From: Geoff Edmonson <[EMAIL PROTECTED]> To: amradio@mailman.qth.net Sent: Wed, 31 Dec 2003 08:54:14 -0600 Subject: Re: [AMRadio] another SX-28 question > I spewed my drink all over the monitor when on Wednesday 31 December > 2003 > 08:48, w5sum said (and I am -not- making this up!):: > > > good morning Jeff > > > > yes there is an AVC switch and it is on... I think the problem is, that > > this is a non linear pot I dug up... measuring the resistance, it moves > > slowly for just a "(little bit)", then it JUMPS quickly... I'm going to > change > > this out first > > Sounds like the culprit. > > While you're checking on things, make sure you know you're not > addressing the whole list ;-) > > -- > 8:52am up 2 days 15:20, 5 users, load average: 0.21, 0.16, 0.19 > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio --- End of Original Message ---
Re: [AMRadio] another SX-28 question
I spewed my drink all over the monitor when on Wednesday 31 December 2003 08:48, w5sum said (and I am -not- making this up!):: > good morning Jeff > > yes there is an AVC switch and it is on... I think the problem is, that > this is a non linear pot I dug up... measuring the resistance, it moves > slowly for just a "(little bit)", then it JUMPS quickly... I'm going to change > this out first Sounds like the culprit. While you're checking on things, make sure you know you're not addressing the whole list ;-) -- 8:52am up 2 days 15:20, 5 users, load average: 0.21, 0.16, 0.19
Re: [AMRadio] another SX-28 question
sorry gang about the language.. I thought that was going just to jeff LOL Happy New Years ya'll R On Wed, 31 Dec 2003 09:48:30 -0500, w5sum wrote > good morning Jeff > > yes there is an AVC switch and it is on... I think the problem is, > that this is a non linear pot I dug up... measuring the resistance, > it moves slowly for just a cunt hair, then it JUMPS quickly... I'm > going to change this out first > > Happy New Year to ya!! > > Ronnie > > On Wed, 31 Dec 2003 07:58:36 -0600, Geoff Edmonson wrote > > > the RF gain control was not working at all. I found a pinched wire that > was > > > grounded. This was the wire going to the cathode resistor of V-1. I fixed > > > this, and even put a new pot in there for the RF Gain. It works BUT.. all > > > you have to do is just barely turn it and it blanks out the front end. > > > Could one of the cathode resistors have changed value, canceling out the > > > work of the rf gain control? R-3 to V-1 or R8 to V-2? Or, possibly, C14 on > > > V-1 or C18 on V-2? > > > > Just a silly-assed question, Ronnie - mainly because I don't remember... > > but is there an AGC control switch on the front of the SX-28? It > > should be ON. Without the AGC circuit being active, you could have > > the same effect - any signal would send the front-end to saturation. > > > > Happy New Year! > > 73 = Best Regards, > > -Geoff/W5OMR > > > > -- > > 7:56am up 2 days 14:23, 4 users, load average: 0.17, 0.65, 0.84 > > > > ___ > > AMRadio mailing list > > AMRadio@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/amradio > > The "AM" voice of Shreveport, Louisiana USA > formerly WN5AIA and WB5AIA > I got my Extra Class the old fashioned way... I earned it! > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio The "AM" voice of Shreveport, Louisiana USA formerly WN5AIA and WB5AIA I got my Extra Class the old fashioned way... I earned it!
Re: [AMRadio] another SX-28 question
good morning Jeff yes there is an AVC switch and it is on... I think the problem is, that this is a non linear pot I dug up... measuring the resistance, it moves slowly for just a cunt hair, then it JUMPS quickly... I'm going to change this out first Happy New Year to ya!! Ronnie On Wed, 31 Dec 2003 07:58:36 -0600, Geoff Edmonson wrote > > the RF gain control was not working at all. I found a pinched wire that was > > grounded. This was the wire going to the cathode resistor of V-1. I fixed > > this, and even put a new pot in there for the RF Gain. It works BUT.. all > > you have to do is just barely turn it and it blanks out the front end. > > Could one of the cathode resistors have changed value, canceling out the > > work of the rf gain control? R-3 to V-1 or R8 to V-2? Or, possibly, C14 on > > V-1 or C18 on V-2? > > Just a silly-assed question, Ronnie - mainly because I don't remember... > but is there an AGC control switch on the front of the SX-28? It > should be ON. Without the AGC circuit being active, you could have > the same effect - any signal would send the front-end to saturation. > > Happy New Year! > 73 = Best Regards, > -Geoff/W5OMR > > -- > 7:56am up 2 days 14:23, 4 users, load average: 0.17, 0.65, 0.84 > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio The "AM" voice of Shreveport, Louisiana USA formerly WN5AIA and WB5AIA I got my Extra Class the old fashioned way... I earned it!
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] another SX-28 question
> the RF gain control was not working at all. I found a pinched wire that was > grounded. This was the wire going to the cathode resistor of V-1. I fixed > this, and even put a new pot in there for the RF Gain. It works BUT.. all > you have to do is just barely turn it and it blanks out the front end. > Could one of the cathode resistors have changed value, canceling out the > work of the rf gain control? R-3 to V-1 or R8 to V-2? Or, possibly, C14 on > V-1 or C18 on V-2? Just a silly-assed question, Ronnie - mainly because I don't remember... but is there an AGC control switch on the front of the SX-28? It should be ON. Without the AGC circuit being active, you could have the same effect - any signal would send the front-end to saturation. Happy New Year! 73 = Best Regards, -Geoff/W5OMR -- 7:56am up 2 days 14:23, 4 users, load average: 0.17, 0.65, 0.84
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
[AMRadio] AM Night
Come join us on 3805 + or - this evening at 8 PM EST for the CRA Collins AM night. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com
RE: [AMRadio] another SX-28 question
Many RF gain controls work by a voltage divider setup, a pot with the wiper going to the cathode of a stage, one terminal going to ground, the other to a positive voltage source. This allows the cathode voltage to go to ground (rf gain max), to a small positive voltage (rf gain minimum). Other circuits use the AGC setup on multiple stages. Don't assume the pot is good, or the correct value. The pinched wire could have ruined the pot, some PO could have changed the pot because of the pinched wire, etc. You need to reference the diagram and check values and connections, many older receivers were modified for better SSB reception (yuk!). If a pot went open, or was too high a value, the rf gain will be normal when the wiper is grounded, but as soon as its off the end point, its open... Many older receivers (not the SX28 I think) did different things with the gain control in SSB/CW mode, on my G76, the audio gain control turns into an RF gain control... On my SX17, the bfo is separate, and does not interact with the RF gain circuit. I think the RF gain control is the voltage divider type. I think there is also an AGC on off switch. Great sounding receivers, all those that Hallicrafters made with the nice push pull audio output, puts receivers that use a 6aq5 or some such to shame, and people don't know what they are missing, listening to good AM on the typical receiver, even high end modern stuff. It sounds better than side band, but it can be as much of a difference between a good and bad audio amp as between ssb and AM. The Scott SLRM receiver I have seems to have a real hi fi audio amp, with no driver transformer in the audio stages, and even a position on the selectivity control marked hi fi. Broad as a barn door! Push pull 25L6 tubes! Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of w5sum > Sent: Tuesday, December 30, 2003 5:47 PM > To: amradio@mailman.qth.net > Subject: [AMRadio] another SX-28 question > > > well 24 hours of work and she is coming along nicely. The > audio section is > fine now. Sound graaat.. > She is not working on the top two bands but we'll cross that > bridge later. > > the RF gain control was not working at all. I found a pinched > wire that was > grounded. This was the wire going to the cathode resistor of > V-1. I fixed > this, and even put a new pot in there for the RF Gain. It > works BUT.. all you > have to do is just barely turn it and it blanks out the front > end. Could one > of the cathode resistors have changed value, canceling out > the work of the rf > gain control? R-3 to V-1 or R8 to V-2? Or, possibly, C14 on > V-1 or C18 on V-2? > > looks like they will be tough to get to if that is the case. > > your ideas gentleman? > > your > The "AM" voice of Shreveport, Louisiana USA > formerly WN5AIA and WB5AIA > I got my Extra Class the old fashioned way... I earned it! > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] SX-28 help
Vince I will be on the air tonight around 9pm your time. BUT, we are having a midnite modulation party starting at 11pm your time on 3880 or 3885, lots of 5 and 4 landers will be on. I would love to try at 9pm your time however, on3885, or 3880, or 3875.. how bout that? Let me know and thanks a heap for considering doing this. Ronnie -- Original Message --- From: Vince Wesa Werber <[EMAIL PROTECTED]> To: amradio@mailman.qth.net Sent: Tue, 30 Dec 2003 19:09:10 + Subject: Re: [AMRadio] SX-28 help > Soo, you need Maine e??? Got a deed right here and the > price is low... heeheeheehee > > Seriously, when are you planning to operate?? I'm good for late at > night or early mornings... You might be able to hear the old > 32V1... who knows... worth a try... :-) vince ka1iic > p.s. I have some QSL cards around here somewhere... > > On Tuesday 30 December 2003 10:52 am, w5sum wrote: > > hi Vince > > man.. I really need Maine bad for my 75M AM WAS. Wonder if we could arrange > > a sked? > > > > Ronnie > > > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio --- End of Original Message ---
[AMRadio] RCA Mixer Board
BC-8 RCA board for sale - $200 - pickup only near Johnstown, PA Removed from service - very presentable next to your heavy metal transmitter or in "studio A" Thank you. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com
Re: [AMRadio] Need advice on storing RF power tubes
I wished that I had used spell check on my post. "attempting" and "during" In my humble opinion, the reason for the filament to shatter, break, snap, open, split; crack, divides, etc. or whatever occurs is physical jarring. However, I had a gentleman in New Zealand ship me two 75TH tubes for my 30K-1 and they arrived in great shape. Think of how many "frequent-flyer miles" these tubes had since leaving the factory in California. Best of everything in 2004. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: "David Knepper" <[EMAIL PROTECTED]> To: Sent: Wednesday, December 31, 2003 6:03 AM Subject: Re: [AMRadio] Need advice on storing RF power tubes > Can anyone explain the difference between the filaments in an ordinary light > bulb with that of a transmitting tube. The point that I am attemting to > make is that outside lighting - like the lights on our barn withstand > tremendous cold durin the winter and then when evening comes, the filament > is shocked with 120 volts. These bulbs seem to last forever, particularly, > street lights. > > I am sure that the filaments are made of different material but thought I > would ask the so-called "experts." > > Thank you and Happy New Year > Dave, W3ST > Secretary to the Collins Radio Association > Publisher of the Collins Journal > www.collinsra.com > - Original Message - > From: "Donald Chester" <[EMAIL PROTECTED]> > To: > Sent: Wednesday, December 31, 2003 4:51 AM > Subject: Re: [AMRadio] Need advice on storing RF power tubes > > > > > > > > >BTW, where in 4-land are you where it gets below zero? I thought you > folks > > >had it easy down there compared to those in the great white north? (o: > > > > Here in north middle TN, it normally gets below zero a time or two each > > winter, but the last few winters have stayed above zero. The coldest I > > personally remember was -18. According to the local highway dep't, it has > > dipped to -20. But that's not normal for this region. > > > > I also have heard the story about cold storage of tubes. I suspect tubes > > like the 250TH, which already have a brittle filament, would not stand > > physical vibration while at that temperature. > > > > Don k4kyv > > > > _ > > Have fun customizing MSN Messenger - learn how here! > > http://www.msnmessenger-download.com/tracking/reach_customize > > > > ___ > > AMRadio mailing list > > AMRadio@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/amradio > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Need advice on storing RF power tubes
Can anyone explain the difference between the filaments in an ordinary light bulb with that of a transmitting tube. The point that I am attemting to make is that outside lighting - like the lights on our barn withstand tremendous cold durin the winter and then when evening comes, the filament is shocked with 120 volts. These bulbs seem to last forever, particularly, street lights. I am sure that the filaments are made of different material but thought I would ask the so-called "experts." Thank you and Happy New Year Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: "Donald Chester" <[EMAIL PROTECTED]> To: Sent: Wednesday, December 31, 2003 4:51 AM Subject: Re: [AMRadio] Need advice on storing RF power tubes > > > >BTW, where in 4-land are you where it gets below zero? I thought you folks > >had it easy down there compared to those in the great white north? (o: > > Here in north middle TN, it normally gets below zero a time or two each > winter, but the last few winters have stayed above zero. The coldest I > personally remember was -18. According to the local highway dep't, it has > dipped to -20. But that's not normal for this region. > > I also have heard the story about cold storage of tubes. I suspect tubes > like the 250TH, which already have a brittle filament, would not stand > physical vibration while at that temperature. > > Don k4kyv > > _ > Have fun customizing MSN Messenger - learn how here! > http://www.msnmessenger-download.com/tracking/reach_customize > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Need advice on storing RF power tubes
BTW, where in 4-land are you where it gets below zero? I thought you folks had it easy down there compared to those in the great white north? (o: Here in north middle TN, it normally gets below zero a time or two each winter, but the last few winters have stayed above zero. The coldest I personally remember was -18. According to the local highway dep't, it has dipped to -20. But that's not normal for this region. I also have heard the story about cold storage of tubes. I suspect tubes like the 250TH, which already have a brittle filament, would not stand physical vibration while at that temperature. Don k4kyv _ Have fun customizing MSN Messenger learn how here! http://www.msnmessenger-download.com/tracking/reach_customize
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. > > Interesting My T11M74 40 watt unit would require a connector somewhat > smaller than a standard bananna plug. I must have a mod transformer similar... the holes are too small for banana jacks, yet the holes are not threaded. *shrug* 73 = Best Regards, -Geoff/Wt5OMR -- 12:17am up 2 days 6:45, 5 users, load average: 0.04, 0.03, 0.00
Re: [AMRadio] Need advice on storing RF power tubes
> > But every once in a while I hear that storing power tubes in a cold > > climate somehow degrades them or renders them useless. > > I remember seeing a warning somewhere a number of years ago about storing > certain power tubes at subzero temperatures. As I remember, the 100TH and > 250TH were mentioned specifically. Seems the tungsten filaments can > contract and fracture. Seems possible, but I have never experienced this > personally and pass along the information for whatever it's worth. I was never warned about storing tubes in the cold (In South Texas, we got to 27 this morning, for about and hour or so, the back to 64 for a high) but I WAS warned by Mr. AM (rip) John L. Mohn/W5MEU - Store them tubes vertically! The filament can sag and fall into the grid, causing a short. At least on the bigger jugs - 811's, 813's, 100TH's, 250TH/L's, etc... Happy New Year y'all 73 = Best Regards, -Geoff/W5OMR -- 12:14am up 2 days 6:41, 5 users, load average: 0.00, 0.00, 0.00
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] Need advice on storing RF power tubes
In a message dated 12/30/03 5:24:07 PM, [EMAIL PROTECTED] writes: > But every once in a while I hear that storing power tubes in a cold > climate somehow degrades them or renders them useless. > All, I remember seeing a warning somewhere a number of years ago about storing certain power tubes at subzero temperatures. As I remember, the 100TH and 250TH were mentioned specifically. Seems the tungsten filaments can contract and fracture. Seems possible, but I have never experienced this personally and pass along the information for whatever it's worth. 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] SX-28 help
Soo, you need Maine e??? Got a deed right here and the price is low... heeheeheehee Seriously, when are you planning to operate?? I'm good for late at night or early mornings... You might be able to hear the old 32V1... who knows... worth a try... :-) vince ka1iic p.s. I have some QSL cards around here somewhere... On Tuesday 30 December 2003 10:52 am, w5sum wrote: > hi Vince > man.. I really need Maine bad for my 75M AM WAS. Wonder if we could arrange > a sked? > > Ronnie >
