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@miamioh.edu>
To: jim@audiosystemsgroup.com
Cc: "amps@contesting.com" <amps@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
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FISTS #11993
SKCC #215
NAQCC #3441
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