T-368 Plate Relay Replacement

[W6TOM]

  I need to replace the plate relay in my T-368, the relay which in my E model is a sealed unit, sticks on, a rap with a stick will reset it but that needs to be repaired. The existing relay has a 120 vac coil.

  I could get another large frame relay or  it has been suggested a mercury wetted relay. One guy I know replaced the plate relay in his BC-610 with a solid state relay, I'm leaning in that direction and have read that there is a variant called a soft start relay. 

  Suggestions and advice appreciated, thanks.

 

[wb3eii]

Schneider (square D) makes some nice, small industrial contactors.
 I use them in some of the equipment at my job, and have been thinking these units are ideal for this use.
 That being said, I haven't tried this yet, but see no reason why it wouldn't work.
 My t3 is b model, has open relay, I put an extra spring on it to cure the sticking.

Traffic signal relay (mercury plunger) has almost zero failure rate, also a good choice.
73

[Opcom]

second on the mercury plunger relays (contactors). Better than solid state unless you have to switch at zero crossing for some reason. They are often cheap on ebay but ask the seller to wrap any with glass ampoules in plenty of bubbles or things could go very wrong.

[W6TOM]

  I'm tending to use a solid state relay, this device on Ebay looks to fit my requirements.

http://www.ebay.com/itm/SSR-40AA-H-40A-Solid-State-Relay-Module-80-280V-AC-90-480V-AC-Heat-Sink-/230913390919?hash=item35c382b947:m:mr6qjinEoptLXugOjfkThkw

  I did see a number of mercury relays on Ebay too that would work, a bit more money. I have a lot of work to do prior to even taking the power supply apart in that I need to make space and also make a suitable area.
 

[W9BHI]

Look for a Crydom A1240 SSR on Ebay.
I used one on my T-368 and it worked fine.
It fits nicely on the bottom of the chassis below the original plate relay.
Use a little heat sink compound under it.
Don

[W2PFY]

Do those solid state relays make that satisfying Ker Clunk sound when activated?

I think for an instant my BC-610D puts out about 10,000 watts when that relay closes
 

[RolandSWL]

Just curious. What are the specs for that plate relay. Would a contactor work?

[W9BHI]

I'm thinking that the object of going with a SSR is to get rid of the arcing/sparking/pitting/sticking relay contacts and adding a bit (very small) of soft start to mix.
My $0.02.
Don

[W6TOM]

  The documentation on these transmitters is not good, there were a number of different versions, mine is a E Model as per the data plate but the data plate is on the RF shelf. The other shelves could have been switched, I notice that my Modulator shelf has slot head screws but the RF and Power Supply shelf has philips screws so the Modulator shelf is likely not original.

 The early models had open frame relays, the newer models such as mine have sealed relays. The antenna relay was a open frame on the early models and then on the later models a vacuum relay, mine has a vacuum relay. The shelves or whole units were supposed to be brought up to current revision when sent in for depot repair.

 The plate relay on my transmitter according to the schematic is a double pole single throw, not a good idea to use parallel contacts. The plate transformer  is protected by a 15 amp breaker, not sure what the inrush current would be on the power supply.

 Anyone have any ideas on that???

 A friend, N7UVZ, who used these transmitters in the military told me they were used 24/7 for RTTY and the Push to Talk service we give them is not what they were probably designed for, Plate Relay failure is a common problem I'm discovering.

 I'm tending toward using a mercury relay because the solid state relays have leakage current.

[W3GMS]

I'm tending toward using a mercury relay because the solid state relays have leakage current.

Leakage current is not an issue since the load presented will take care of the very small amount of leakage current. 

Joe-GMS

[KD6VXI]

Maybe a snubber across the contacts as well?   May help to decrease pitting.   

May have unwanted side effects,  dunno.

--Shane
KD6VXI

[M1ECY]

Be aware, in my experience SSR tend to fail short circuit.... this will mean anything they switch being left on.....