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Re: [TenTec] SB-220 Tubes and QSK

To: tentec@contesting.com
Subject: Re: [TenTec] SB-220 Tubes and QSK
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Reply-to: geraldj@storm.weather.net,Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 29 Oct 2007 21:18:08 -0600
List-post: <mailto:tentec@contesting.com>
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

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