Amps
[Top] [All Lists]

[AMPS] SB-220 conundrum

To: <amps@contesting.com>
Subject: [AMPS] SB-220 conundrum
From: rakefet@rakefet.com (Vic Rosenthal)
Date: Tue, 18 Jan 2000 08:39:47 -0800
Pete Smith wrote:
> 
> 2.  But on 40m, power output (PLATE and LOAD tuned for maximum) is ~1450w,
> grid current ~250 ma. and Plate current ~900 ma.  There is also a fairly
> striking difference between the PLATE setting in this condition and the
> setting for minimum plate current.  If I tune the PLATE for minimum plate
> current and LOAD for maximum output, the figures look much more like those
> on the other bands.

An off-the-wall guess:  I recall that with grid-driven amps, a big difference
between the point of minimum current and maximum output was often indicative of
improper neutralization -- in other words, feedback from the amp's output to the
input.  Perhaps in changing the relays, you did something which increased the
output-to-input coupling.  Is the braid of the coax from the input relay to the
cathode circuit grounded at both ends?  I could imagine some kind of stray
resonance in this cable...

73,
Vic, K2VCO
Fresno CA

--
FAQ on WWW:               http://www.contesting.com/ampsfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm


<Prev in Thread] Current Thread [Next in Thread>