I have no experience with Vacuum switches.
The Magnecraft reed-relay (SPST) I had between HVPS and plate choke began to stick. Thankfully, a safety habit of 'discharge before touching' paid off with only a frightful bang! Autopsy to look inside relay: 2 flat metal strips in a glass tube (non-vacuum) passing through a coil -all covered in wax- in a plastic case. I'm surprised it lasted as long as it did given it's low 2-digit current rating. Another learning experience & now it's onward to a proper vacuum relay.
I ordered the cheapest but new SPST vacuum switch I could find: A Soviet relay rated for 10A, needs 22vdc to keep closed so it should substitute without a fuss. About 2" tall pic attached if I can upload. I like the G3SEK circuit that opens a relay disconnecting HV to RF deck when a fault is detected. I placed it between HVPS and plate choke. I do recognize DC is hard on relay contacts. The relay stays closed after warm-up, rather than opening & closing with each T-R cycle. If placed in an AC line it would be either: pre-FWB or on the primary side of Plate Transformer. Both those locations would conflict with the Soft-Start. I found this decision process confusing and I'm still not certain about it. Relay location was more of a default but the Magnecraft did work well in same location for awhile. Only remaining option I can see is not using the circuit at all.
gotta cut this short
neil, n2eye
The Magnecraft reed-relay (SPST) I had between HVPS and plate choke began to stick. Thankfully, a safety habit of 'discharge before touching' paid off with only a frightful bang! Autopsy to look inside relay: 2 flat metal strips in a glass tube (non-vacuum) passing through a coil -all covered in wax- in a plastic case. I'm surprised it lasted as long as it did given it's low 2-digit current rating. Another learning experience & now it's onward to a proper vacuum relay.
I ordered the cheapest but new SPST vacuum switch I could find: A Soviet relay rated for 10A, needs 22vdc to keep closed so it should substitute without a fuss. About 2" tall pic attached if I can upload. I like the G3SEK circuit that opens a relay disconnecting HV to RF deck when a fault is detected. I placed it between HVPS and plate choke. I do recognize DC is hard on relay contacts. The relay stays closed after warm-up, rather than opening & closing with each T-R cycle. If placed in an AC line it would be either: pre-FWB or on the primary side of Plate Transformer. Both those locations would conflict with the Soft-Start. I found this decision process confusing and I'm still not certain about it. Relay location was more of a default but the Magnecraft did work well in same location for awhile. Only remaining option I can see is not using the circuit at all.
gotta cut this short
neil, n2eye