[Kenwood] TS-930 Sensitivity

Tue Jan 4 16:39:30 EST 2005

Most likely it is the ATT relays. They are good about being intermittent. 
There are NO plated thru holes on the Signal unit of the 930 so that's out.
Don't even think about trying to align the filters with less than a network 
analyzer. The odds of that being the problem are slim to none and the odds 
of misaligning the filter is almost 100%.
Leaky diodes are easy to find, compare the voltages on each side to known 
good ones. It also will locate open ones. While there make sure that only 
one set of filters is turned on at a time. An intermittent connection in the 
logic to the signal unit can turn on 2 at once and it will behave almost 
exactly as described.
Clif Holland, KA5IPF
www.avvid.com
----- Original Message ----- 
From: "Jim Dicso" <dicso123 at hotmail.com>
To: <kenwood at mailman.qth.net>
Sent: Tuesday, January 04, 2005 11:46 AM
Subject: [Kenwood] TS-930 Sensitivity
I have sensitivity problems on at least two bands in a TS-930 (one of two 
that I have in the shack).
I've followed the previous work on improving TS-930's and planned to replace 
suspect PIN diodes. However, I couldn't resolve part #'s from PDF versions 
of the Signal Board so I was testing all the suspect diodes with a digitial 
multimeter and signal injection and range switching. Unfortunately, in 
order to reach all the test points (and to replace the diodes), it looks 
like lot's of screws and cables need to be removed.
I took a step back and measured sensitivity on both units for all bands 
using an HP 8640B and min discernible signal (speaker).
....somewhat subjective but questionable readings were doublechecked. 
Originally, this test produced low (approx -75db) sensitivity on 18.1 and 
14.2 Mhz but this comparison produced no readings higher than -125db.
Has this problem surfaced because of thru hole problems? (I could have 
changed the contact by probing)
Is this now an alignment problem? Will BPF tuning help me get to the -135 
dB/-140 dB sensitivity I found on many bands?
Thanks, Jim K2SZ
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