[Boatanchors] WTB: Knightkit T-60 Transmitter

[Spooner, Robert L]

Rob,

That's a nice, simple solution. Thanks. There's merit to simplicity.

73,
Bob AD3K

________________________________
From: Rob Atkinson <ranchorobbo at gmail.com>
Sent: Tuesday, June 23, 2020 10:17 AM
To: Spooner, Robert L <rls19 at psu.edu>
Cc: Rich Arland <k7sz at live.com>; boatanchors at mailman.qth.net <boatanchors at mailman.qth.net>; Grant Youngman <ghyoungman at gmail.com>
Subject: Re: [Boatanchors] WTB: Knightkit T-60 Transmitter

The Valiant has a lower Vd under load probably because the rectifiers
have a lower Vd than what is seen with vacuum rectifiers.

I don't know what kind of keying the Viking 1 has, but if it is
cathode keyed, the rise and fall time can be shaped.  put a 3 or 4 mfd
cap from the cathode to ground.   Make an oscilloscope tap that can be
inserted into the feedline.  You can take a small project box and put
UHF jacks, one on each end of the box with a copper tubing from the
pins inside to each other.   On the side of the box mount a BNC jack
and connect its pin inside to a small copper wire, AWG14 or smaller,
bent in the shape of a L so it is parallel to the tubing and an inch
or so away.  Insert this in the feedline to a dummy load and connect
the BNC jack to the vertical input on an oscilloscope.   Fire up the
rig and key it into the DL and adjust the scope so you trigger on the
keying and set the sweep time to give you a look at the rise.
Actually do this before adding the cathode capacitor so you can see
the unmodified rise time first.   Add the cap to the Viking and check.
There should be a time constant upon keying whereby the cap discharges
and slows down the pull of cathode to ground so the envelope isn't
instantaneous.   On key up the cap charges, slowing down the tube
cutoff, so you should see something like /   and  \  instead of |
and  |.   You can try different capacitance values to get it the way
you want it, but that should end the key clicks.

73

Rob
K5UJ