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

[Kevin]

Jim,

My TS-520 does not have a "power control" like my K3. My fathers 
TS-450SAT does have a power control. I used to use the 520 on PSK31 and 
MFSK. I'd tune it for maximum smoke on SSB and then feed it negative ALC 
voltage from a 9V battery through a pot to control output power. Get it 
right down to 25W and the IMD readings from my IMD meter would be -35 or 
better. I did AFSK RTTY the same way.

I assume the reason it worked so well was because the ALC voltage did 
not vary with the transmitted signal. Otherwise it was a royal PITA 
messing with the drive control, carrier control, and mic gain.


On 1/3/2017 4:55 PM, Jim Thomson wrote:
> 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
>
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>

-- 
R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441


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