"Hi Folks
Its me again i have never used a amp before so i am new at this.1st of
all let me thank everyone who responded to my prior question.Still concerned
abt interfacing this swan mark-1 to the knwd 940.
Is the keying in the amp negitive or positive ?How much voltage,Could i
try the amp by using a foot switch to key it.Key the amp first.Ameitron
makes a interface but that is for positive keying.How abt tuned input and
alc circuits.Dumb questions i suppose,anyways,tnx in advance..de
Dale..KA5WHO in NH"
The subject line says Mark -2. The text says Mark -1. I am responding as
if the amp is a Mark II, since I am not familiar with the Mark - 1.
The Mark II has a relay voltage of 18 volts and the current switched if 400
ma. It is a positive voltage. I am not familiar with the 940, but I
believe it can switch that much current. Check the manual for the 940. It
is quite easy to either use another relay or a transistor circuit to reduce
current if necessary. The 18 volts will be no problem. The relay is
protected with a "back-diode".
The Mark - 2 does not have a tuned input. You will still be able to operate
with your 940, however, the swr may be a bit high. You can improve things
by using an external tuner at the input of the amplifier. The shorter the
cable, the better. Or, you can do as I did and install a pi-network input
circuit. This will reduce distortion a bit and improve swr.
ALC circuits are a bad joke, in most cases. They are quite useful if your
amp has a capacity well over the legal limit and you want to assure that you
remain legal. However, if your amp flattens out with full drive, the
leading edge will still be there even with alc and you will not make a lot
of new friends on the air. Better to forget about ALC.
Regarding dumb questions, I have a close friend who asked more dumb
questions than anyone I knew. He also designed an oscilloscope 45 years ago
that would go to 2 ghz, while others were trying to get to 30 mhz.
73, Colin K7FM
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