Thanks Carl and others for the replies. I don't plan to use this amp above
20m actually. One of my relays is very similar to the SB-220 relay - and
thinking I'd use the same setup with a third pole for the bias circuit.
BUT, I surely do not want to lose any significant signal in RX mode.
Are the "general pupose" relays considered "open-frame" - I am referring to
those where you can see the working parts through a clear plastic shell.
They are used in my Amertiron remote coax switch and Ameritron rates those
at 4kw HF.
> Many amps used open frame relays with 10-13A contacts and they worked well
> at 1500W. The one issue with them is high VSWR in the thru position on 10M
> which can fold back the power in a SS rig. The cure is simple, add a
> capacitor from the thru loop to ground to tune out the Xl.
> You can use an adjustable mica trimmer and leave it or measure the value
> and replace with a 1KV disc ceramic or 500V mica. Typical values are 25-35
> pf. Any one will handle 100W with ease.
>>I have several open-frame relays. If I use one for the T/R relay, what
>>should the contact rating be for a 1500w amp? Is it as simple as 1500w /
>>50 ohms = SQRT of 30A or 5.5 Amps?
>> Steve, KK7UV
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