[Amps] FCC Denies Expert Linears' Request for Waiver of

[Jim Thomson]

Date: Tue, 3 Jan 2017 13:31:37 -0700
From: MU 4CX250B <4cx250b at miamioh.edu>
To: jim at audiosystemsgroup.com
Cc: "amps at contesting.com" <amps at contesting.com>
Subject: Re: [Amps] FCC Denies Expert Linears' Request for Waiver of
15 dB Rule

I remember that with the Drake C-Line, some ops would short the T4XC
ALC line, which would increase the power output to 175W. Most vacuum
tube transmitters I am familiar with did not have a power adjustment.
Even the mighty solid state Collins KWM-380 lacks a power adjustment.
73,
Jim w8zr

##  I owned several new C lines.... and you wont get any 175 watts out of any of them
with the ALC shorted out. All that shorting out the ALC line did...was increase the talk
power a whole bunch on ssb.   Pep out stayed the same.  Average went way up. 

##  For ALC between the xcvr and amplifier in question to even work correctly, the
time constant in the xcvrs  alc  has to match the time constant in the amps  alc circuit. 
The drake L4B wont work with the Drake TR7.   Ditto  with a drake L7 and a drake
T4XC.   An  ALC  cap has to be swapped out to a different value in both those amps.

##  T4XC  + L4B  require no cap changes, alc is matched  for time constants....
ditto with TR7 +  L7.      

##  If the amp in question doesnt have adjustable ALC,  it still wont work properly. 
Both the L7 and L4B have adjustable alc.  There is NO power output control on the drake
T4X series, nor the TR3 /4 series.   The adjustable ALC on the drake amps was the only way
to tweak the po of the exciter. 

## there were several of the kenwood  SS xcvrs, like the  TS-450 I believe  that had no PO control. 
They ran flat out.... so again, if driving amp, the alc line to the amp had to be installed..and the amp had
to have adjustable alc.

##   back then using a xcvr that put out 130 watts pep, with an amp that required 100w of drive would work
fine, with the alc line installed and tweaked correctly.   The problems started when some bozo tried to use his
swan 500-700 CX to drive a SB-200,  or  8877,  then  try and rely on the alc connection between em..to keep things
under control.   Didnt work. 

##  even on the older  SS xcvrs that had no PO control,  you could still  control the output on ssb mode, by inserting
a low value of  dc voltage on the alc buss  on the back of the xcvr.  -9 vdc  from a battery, through a 50k pot, tweaked
correctly works just fine.  Then you can dial up exactly how much pep out u want on ssb mode.   You have already 
developed the ALC voltage.   Scream all u want, but you wont exceed say.... 65 watts, or whatever its tweaked to. 

## another method is to use limiters and distortion cancelled clippers in the audio chain, results are the same.  

Jim   VE7RF