[TenTec] amps

Mike Hyder -N4NT- n4nt_m_o_hyder at charter.net
Sat Aug 6 11:30:14 EDT 2005

I ran an SB-220 for about 28 years, the last 20 or so with various Ten-Tecs. 
About 10 years ago I got concerned that the SB-220's antenna relay required 
switching more voltage and current than the Ten-Tecs might handle without 
damage to their amplifier switching relays so I bought the "Soft Key" module 
I think it's called from Harbach electronics (now at 
http://www.harbachelectronics.com/ ).

I work only CW.  I turned the drop-out delay on the rig's amplifier 
switching relay to the maximum.  When I was sending, I could easily hear any 
but the very weakest signal trying to break in.  A good effect was that the 
overall receiver noise was reduced while sending.  I know that the amplifier 
was switching "hot" as it went to transmit but that never seemed to make any 
difference and in all the time I used it, the amplifier's antenna relay 
contacts did not seem any the worse for wear.

Rich Measures has written pretty extensively on the SB-220, including how to 
convert it to a full QSK amplifier.  You can find his work here: 

73, Mike N4NT

----- Original Message ----- 
From: "JOHN" <ku3g at yahoo.com>
To: <tentec at contesting.com>
Sent: Saturday, August 06, 2005 11:09 AM
Subject: [TenTec] amps

Does anyone have any info on keyin a sb 200 or sb220 with and omni vi
thanks 73
john ku3g 

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