Hello all I am in need of a relay for the SB-230 Linear Amplifier Heathkit part # 69-55 Any information where I might find one would be appreciated 73 Bob KD9DDE
It's the same as the relay used in the SB-220: Available here: https://harbachelectronics.com/shop/heathkit-sb220-sb221/ry-220-replacement-tr-relay/
Actually it’s NOT the same as in the SB220. It’s more like the same one in the SB200!! Yes it’s 120vdc but it’s bigger and a 3pdt whereas the 230 relay and 200 relays are DPDT and smaller. Since the coil plays a part in the bias there may be an issue with bias because of the difference of impedance of the coil. Will probably work but it’s certainly not the same.
That's interesting. I remember the SB200 relay is DPDT and the SB220 is 3PDT, but the last SB230 I looked at (years ago) was also 3PDT just like the SB220, and they did not use one set of contacts; so, it was a 3PDT used like a DPDT and it sure looked original. Maybe someone had replaced it before I looked at it. I made a note in my "repair notes" which is all hand-written (!) over many years that the 230 used a 3PDT with only two poles connected and figured that's the way they all were.
Thanks for your reply. The original relay in the SB-230 I have is a 3pdt relay. They do not use the center section of the relay. My original assembly manual also shows a 3pdt relay. Perhaps they switched at some point to improve the bias on the output tube.
Thanks for the update. You are correct. My original unit comes with the 3pdt relay. Perhaps they switched to improve the bias on the output tube. See photos on previous reply
That's what I remember, also. They may have actually switched the other way around, starting out with a DPDT because that's what was in the SB-200, then switching to the 3PDT because the SB-220 was a newer model and in current production, so they just used a common relay for the 220 and 230.
