[TenTec] SB-220 Tubes and QSK

[Dr. Gerald N. Johnson]

On Mon, 2007-10-29 at 22:06 -0500, N4YG wrote:
> I just want to thank everyone who advised me to buy the RF Parts 3-500ZG tubes for my SB-220. I am very pleased with the tubes. I have about 20% more output power and it is almost unbelievable how much cooler the amp runs.
> 
> I also completed the QSK mod for the radio, based in large part on the info on Rich Measures' web site. I am also very please with that and all works well with the OMNI VI +.
> 
> I would like to mention one thing. I believe that many of you have installed the Soft Key mod in the SB-220. I have studied the schematic for Soft Key extensively. I have a much simpler circuit which you can build in a short time for an expenditure of only a couple of bucks. It works great. I do not know if the name "Soft Key" is intended to be descriptive of the mod or not, but its keying is certainly not soft, in fact, why would one want to key the amplifier T-R relay softly. Anyone who wishes to know how to build and install my circuit can obtain details by sending me an email.
> 
> Joe

I think the soft part of the name comes from it taking little power so
the weak outputs of a solid state radio can key it without damage to
those weak outputs.

Can you measure 20% at the other end of the path? That's all of 0.8 dB
and when propagation changes sometimes more than 10 dB in seconds...

73, Jerry, K0CQ