The relay is a Jennings RJ1A styled vacuum relay and is a # RJ1A-26N969 The usual source to find these (Max-Gain) has found it difficult to obtain these surplus as of late, I bought the last one he had and he doesn't expect to be getting any in for a while. Sometimes they show up on ebay and you'll see them at Dayton. Do a google to find a photo of one. Here's a link to W6MQI web page where he used two of them in his Alpha 76A http://home.comcast.net/~daveandjill41/site/?/page/Alpha_76a_mods_/&PHPSESSID=7df6080b9823c4db528264be0b14ef1a
I've thought about this and it would be easy to make the equivalent:
Drill a hole in a piece of thin scrap aluminum, plastic or phenolic and mount an existing RJ1A or HC1A relay on it & finger tighten the nut to keep it in place.
Solder 3/4"" maybe 14 gauge wire into the relay terminals, the largest wire that fits inside the relay terminals.
Cut a PVC or other hard tube that the ID is 1/4" or so wider than the metal ring on the relay and tall enough that only 1/4" of the soldered wires show above.
Put this tube over the relay & center it on the aluminum.
Draw a line around the base so as to keep the position correct.
Mark on the aluminum, outside the ring, where the COM, NC & NO are located (The com is at 6 o O'clock, the NC is at 2:30 & the NO is at 9:30 )
Apply silicone grease to the inside of the tube and on the top of the aluminum sheet & a bit past the ring you drew.
Now fill the tube & envelop the relay with silicone caulk till the caulk is flush with the top.
Let it cure for at least a day for the thick silicone to solidify throughout.
Now pull off the tube which never adhered because of the silicone grease you put on earlier & then remove the relay which will also be unattached to the aluminum for the same reason.
Wipe it off & you'll be good to go.
When I say this relay is almost completely silent, it's about as loud as dropping a fresh pea 1/2" onto a counter top. Amazing how much difference that silicone makes. I will definitely do the same with a homebrew external QSK box which uses a pair of RJ1A vacuum relays which I used with my AL-1500. I'll keep that ext. relay when I sell the amp and will use it with an old Canadian Vector amp that uses two 3-500Z but has a loud relay. As I almost only use CW, a silent QSK relay is a real pleasure on full break in.