[Amps] Fwd: Re: Modern rig amplifier keying

Stan Gammons s_gammons at charter.net
Sat Jul 20 20:09:31 EDT 2019

Someone ask what amp and rig. The amp is a Clipperton-L I converted to a 
pair of GI-7BT tubes. Relay is 12 volts and draws around 100 ma when the 
coil is energized.  I haven't decided on a rig, but was considering a 
TS-590SG. I see 10 milliamps is all the TS-590SG will switch. So, I 
decided to re-engineer a Harbach SK-401 I had left over after installing 
a ES4L4-B in my L-4B.  Around 15 volts was the minimum voltage the 
SK-401 would operate at, so I swapped R1 and R2, 22k 1/4 w resistors, 
with 18K 1/4 watt resistors and the circuit will now operate with 12 
volts, possibly lower though I didn't try it. I measured .788 milliamps 
to trigger the SK-401, so I think it will be fine to use with the 
TS-590SG or possibly any other modern rig. The youngest rig I have is a 
Omni VI.

Thanks again for all of the replies.



On 7/20/2019 9:34 AM, Glen Zook wrote:
> Having 12-volts on the keying circuit (actually, usually, 13.8-volts) 
> is very common and I don't know of any "modern" transceiver that 
> cannot handle the voltage.
> Glen, K9STH
> Website: https://k9sth.net
> On Saturday, July 20, 2019, 08:32:43 AM CDT, Stan Gammons 
> <s_gammons at charter.net> wrote:
> How much voltage will modern rigs tolerate on the keying circuit? I have
> an older amp that has a 12 volt relay. Will that fry the keying circuit
> of a modern rig?
> 73
> Stan

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