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Author Topic: TL-922A Relay RL-1  (Read 5616 times)
WA4JQS
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« on: February 19, 2018, 04:58:27 PM »

My 922A has started acting like the relay is either not closing all the way or the contacts have become dirty / pitted after 25 years of use. could be the spring also. sometimes when i un-key the amp the receive will drop down to about half of what it was on the  950sdx. if i key the amp the receiver will come back up. just to make sure it was not the  950sdx  relay put the amp in standby.. worked fine. with the amp back in line about every 8 or 9th transmission it will drop down again.  What i wonder before i pull the amp out of the console . is RL -1 a plug in relay that i can change or at least clean the contact on ? Does anyone carry a replacement relay ?
Thanks 73
Tony wa4jqs
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K6AER
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« Reply #1 on: February 19, 2018, 05:39:35 PM »

The T/R relay is a 110 VDC DPDT open frame relay. You can buy  a replacement from Digikey. Not an easy replacement located next to the tank circuit and is accessible only from the bottom of the amplifier but the hold down nut has to be done from the top. It is a PITA to remove. If you have to clean the contacts just replace the relay. Be carful removing the Choke coil.

You can also use the T/R relay from Harbach Electronics for the SB-220 but the wiring locations will be different and a new mounting hole will have to be added.


Some folks might want to put in a QSK relay. Dick Kessler used to make a kit but I think he is out of the TL-922 business now.
« Last Edit: February 19, 2018, 05:42:20 PM by K6AER » Logged
WA4JQS
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« Reply #2 on: February 19, 2018, 06:01:55 PM »

Thanks i figured it would be a real pain.. hi hi.. from looking at the pic in the book..
73 Tony WA4JQS
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K6AER
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« Reply #3 on: February 19, 2018, 06:09:57 PM »

You solder the coax on the relay before putting the relay into the relay cavity.
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WA4JQS
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« Reply #4 on: February 19, 2018, 06:51:53 PM »

Mike thanks for the tip . i have made a not of that . always looking for good tips hihi
looks like it will be about like recapping a sx 28 or 32 hi hi.. a real pain to get to the switch caps.
it has been a great amp. used it at VP8SSI in 92 and 3Y0PI  in  94.. and lots of contests later. still has org tubes and full output.
just the relay starting to show its age.
73 Tony WA4JQS
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WA7PRC
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« Reply #5 on: February 19, 2018, 09:37:58 PM »

My 922A has started acting like the relay is either not closing all the way or the contacts have become dirty / pitted after 25 years of use. could be the spring also. sometimes when i un-key the amp the receive will drop down to about half of what it was on the  950sdx. if i key the amp the receiver will come back up. just to make sure it was not the  950sdx  relay put the amp in standby.. worked fine. with the amp back in line about every 8 or 9th transmission it will drop down again.  What i wonder before i pull the amp out of the console . is RL -1 a plug in relay that i can change or at least clean the contact on ? Does anyone carry a replacement relay ?
Relays with contacts that aren't hermetically sealed need a "wetting" current passed thru them to prevent oxidation. The relays used to switch RF in most ham amplifiers "dry" switch, and they eventually start to intermit. This usually happens to the N.C. (bypass) contacts. The relays are also very S-L-O-W, potentially "hot" switching (the input switch doesn't close before RF gets to the N.O. contacts).

The TL-922 is known for both problems. You can bend the contacts closer to alleviate the hot switching but, you still have the oxidation problem. The best fix for both is to use vacuum relays that have sealed contacts, and switch faster than the rig can produce RF. Jim W7RY (QRZ bio) produces a PCB that drives vacuum and reed relays. The fastest rigs produce RF in about 5ms but, the relays Jim suggest measured at 1ms (for the slowest relay contacts). Other systems use an outboard sequencer (delay) box to prevent RF from happening before the relays switch. Or, some rigs can be optioned to delay RF. However, if the amplifier is faster than the rig, nothing special is needed. And, with sealed contacts, they'll likely outlast you.

In addition to presenting a low voltage & low current load to the rig's T/R output, Jim's board also provides electronically regulated & switched bias, and LED drivers. He sells on eBay as seller 'radioamplifiers' (link). You get a bare board. When you make your purchase, he emails complete documentation, and a link to the Bill Of Material on Mouser. He doesn't sell the vacuum relay for the output but instead, suggests Max Gain Systems (link) as a source. He offers a suitable reed relay for the input switch, for a reasonable cost. I bought and like his board for my Heathkit SB-220. However, at the time, I found a better deal for vacuum relays on eBay.

Bryan WA7PRC
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WA4JQS
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« Reply #6 on: February 20, 2018, 01:07:28 PM »

Thanks I have known Jim from our RTTY contest days. ill drop him a note
73 Tony
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AA2UK
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« Reply #7 on: February 20, 2018, 02:04:57 PM »

I gave up on internal open frame RF relays a long time ago. I have used Tohtsu relays in a bypass/ amp in/out config. The relays are external and the RF cabling inside the amplifier are modified for direct connection to the input and output connectors. I typically use a BNC relay for the input and an N connector for the output. If I have to replace the internal coaxial cable I use RG-142. Here's an example of the circuit, http://qro-parts.com/product_info.php?products_id=102 (I don't use the relays in this example). You could also use a single high power bypass relay.
This allows me to use a sequencer (DEMI) to close the RF relays before any bias is applied to the amplifier eliminating hot switching while providing modern rigs with a low current interface for the amp bias.
Bill, AA2UK
« Last Edit: February 20, 2018, 02:08:37 PM by AA2UK » Logged
K6AER
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« Reply #8 on: February 21, 2018, 09:19:33 AM »

Bill,

Thanks for the info. I am in the process of modifying a TL-922A with some basic mods such as 10 meters, keying and a possible QSK relay. I went out to look at the Russian relays you listed and they are big. I also have a feeling they or noisy as well. Several folks have made QSK kits for the TL-922 series over the years but they have moved on. One nice set of mods was provided by Don Kessler back in the late 90's. I guess I can home brew my own. Gigavac used to offer ham discounts.

Mike
« Last Edit: February 21, 2018, 09:21:37 AM by K6AER » Logged
AA2UK
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« Reply #9 on: February 21, 2018, 09:47:48 AM »

I do not recommend the Russian relays i was simply showing the circuit. I use Tohtsu relays they are very quiet but in my case I don't want the relays inside the cabinet.
https://www.rfparts.com/relays/relays-tohtsu.html
QSK isn't an option I need or want. relays meet their MTBF's fast enough QSK adds to this exponentially.
Bill, AA2UK
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WA7PRC
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« Reply #10 on: February 22, 2018, 03:51:36 AM »

Unfortunately, many think of Morse when the term "QSK" is used. In fact, when you consider the number of ON/OFF operations used in Morse, it won't take very long to "hit the wall" of a few million open/closed relay operations when used in full Morse QSK.

The points are to avoid hot-switching, and oxidized contacts. Vacuum relays accomplish both. Tohtsu's offerings do neither. The only thing you get with them is usability above 30 MHz... that the TL922 doesn't do. According to the several Tohtsu datasheets I saw, the fastest i about 15ms (about three times the fastes rig can produce RF). A delay/sequencer is still needed, and the OE relays might as well be used.

OTOH, FAST hermetically sealed relays fixes both problems. Whether he uses the W7RY setup or homebrews his own, Tony WA4JQS is on the right track.
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AA2UK
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« Reply #11 on: February 22, 2018, 04:29:48 AM »

Thanks I hit those points.
Bill, AA2UK
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WA7PRC
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« Reply #12 on: February 22, 2018, 05:16:52 AM »

You're welcome, and I pointed out that none of the Tohtsu relays are suitable (by themselves) to avoid hot switching and oxidized contacts... the biggest concerns in this application. Vacuum relays generally are fast enough.

I do however apologize for my tpyos. Wink
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W1QJ
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« Reply #13 on: February 22, 2018, 05:40:31 AM »

I've recently had occasion to visit the QSK realm of vintage amplifiers.  I guided a friend of mine through the entire process of installing a W7RY QSK system in his SB-220 amp.  He used Jim's PC board and Jim's small input relay, and I sold him an HC-1 Gigavac relay.  After a few sessions working together on it using Facebook messenger, we were able to send instant photos so that there was no question as to what was being done on the other end.  At completion it worked first time and flawlessly.  It seemed that the hardest part  (for him) was the mechanical process of fabricating mounting for the HC-1 relay and how to integrate the connections to the board with the amp itself.  This is where I came in.  Once completed he is totally delighted with it.  The "big buck" item in this system is the vacuum relay and a new one is going to cost you about $100 to get into your hands.  With the limited cycle life of these relays you probably won't want to use a used relay. As pointed out by PRC it doesn't take long to use up the cycles if you are an avid CW op.  

I was recently going over the MFJ catalog and I spotted an interesting relay they offer.  It is a high speed relay made by Gigagvac I think it is that sells for $20.  This relay is rated for QSK and can easily handle the RF current from an SB-220,922 and most amps with 3-500 tubes of less.  Seeing as these are the amps that don't have QSK these days, this relay should be fine in place of an expensive HC-1 or RJ-1a.  The MFJ (Gigavac) relay is small and made to be mounted on a board.  Jim's input relay is tiny also.  I believe if Jim gets creative with a new board, he can make a PC board with all the circuitry and can easily add the two relays as part of the board.  This would drastically reduce the cost and make the installation of the entire QSK system much easier.  

The last time I talked with Jim with an idea, we now have the 10 capacitor/diode  board  for the AL-82/1200/1500 which addresses the main problem with those amps.

 
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WA7PRC
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« Reply #14 on: February 22, 2018, 06:34:57 AM »

The "big buck" item in this system is the vacuum relay and a new one is going to cost you about $100 to get into your hands.
I found 3/$80 RJ1s unused surplus shipped on eBay. Typically, they run about that much each, ONE time. It would be bad however, if they needed replacing often.

With the limited cycle life of these relays you probably won't want to use a used relay. As pointed out by PRC it doesn't take long to use up the cycles if you are an avid CW op.
FULL break-in would be a problem. Semi break-in, not so much. Look at it as VOX on fone w/ shorter vs longer delay. In all cases, you want the RX-TX transition to be faster than RF can get to the relay contacts.

I was recently going over the MFJ catalog and I spotted an interesting relay they offer.  It is a high speed relay made by Gigagvac I think it is that sells for $20.  This relay is rated for QSK and can easily handle the RF current from an SB-220,922 and most amps with 3-500 tubes of less.  Seeing as these are the amps that don't have QSK these days, this relay should be fine in place of an expensive HC-1 or RJ-1a.  The MFJ (Gigavac) relay is small and made to be mounted on a board.  Jim's input relay is tiny also.  I believe if Jim gets creative with a new board, he can make a PC board with all the circuitry and can easily add the two relays as part of the board.  This would drastically reduce the cost and make the installation of the entire QSK system much easier.
I've seen those relays in the catalog (pn 408-8100 & 408-8500). However, they don't state the transition time. The #408-8100 is Kilovac #S05FJA238 (now obsolete & no data available, link). I see they're also listed as having single throw contacts. The latter may just be a misprint, as you'd need double throw contacts for T/R function.

For the vacuum relay (output switch) and reed relay (input switch) recommended by W7RY, the WORST case transition time was just barely 1 millisecond. The fastest any rig can produce RF is about 5 milliseconds.
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