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[TenTec] QSK switching diodes in Scout

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: [TenTec] QSK switching diodes in Scout
From: Gary J FollettDukes HiFi <dukeshifi@comcast.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 15 May 2016 20:04:45 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
I tried searching before asking the reflector for a solution to this issue, no 
luck, so, here goes…

I have a Scout that works perfectly up through 30 meters.

Above 30 meters, the TX power drops a LOT after a few seconds transmitting.

I know why it does so. The two diodes D3 and D4 on theLLD/ALC board get very 
hot and allow TX power to leak through. This causes a pullback in output power 
as the perceived impedance of the load drops.

If I lift one of the switching diodes, D3, everything is fine, full output as 
long as I want to stay keyed, even on 10 meters. Of course, there is no receive 
as D3 is the receive signal path from the antenna.

My question is, does anyone know why Ten Tec chose to use 1N3007 diodes here? 
This would seem to be a poor choice as these are not particularly fast diodes.

Has anyone tried PIN diodes here? If so, what type was successful?

I guess I could select some but would rather benefit from others' successes.


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