Wiring A Tank

[W9ZSL]

Well, I scored a NOS Air-Dux 195-2 coil assembly over the weekend.  I have one of those heavy-duty surplus switches to go with it.  My question has to do with tapping. I've seen some "top-screw" coil clamps with tabs for soldering on a wire to the switch. What do you recommend for wire and where can I buy some?  I've heard a lot about the teflon stuff.  I'm doing a single 813 running at least 1900 volts on the plate.  I want to use something flexible.  This is the last part needed for building that 350 watt +/- amp. Outside of the switching, I'll be using some silver-coated straps salvaged from a BC-1T for the RF connections.  At this point, I have all the parts I need to start building.

[Opcom]

humble suggestion:

On a big tank like that, a small strip of copper can be wrapped/formed around the tank wire and tightened with a little screw like a 4-40, the tab being soldered to wire braid going to the switch. The tightness could be improved by a comparatively large-ish brass washer on each side of the folded-together strip.
When taps are in satisfactory places, solder them in place.

[N8ETQ]

  Simulate the the plate load with resistors, pump a
signal from a low power TX backwards into the thing
with a SWR meter in line. With no Voltages applied
to the AMP you should be able to find a 50 ohm point.
Once found there will be no reason to move them.
Hobby Brass works well.

  Here is a pix of an AL-80 Tank.  Make sure the
amp "See's" the bleeders for the plate supply and
screen supply.  With the simulated plate load hooked
to the plate and ground you should be able to
"SWAG" the approximate tap point.  Hook on there
and use a regular #2 pencil and touch the coil a
little either side of your "SWAG". The point where
it doesn't change the SWR is where you want it.
Use a frequency in the center of the band.

  Of course you will need to adjust the tune and
load "C" for min SWR. The AMP will need to be almost
complete for this process.  This works well. On
a VHF/UHF amp you need to have Fil. on, I have
not noticed much change on HF amps with fil on or
off. It's also a nifty way to "Pre Tune" the amp
when testing.

GL

/Dan


  I added a pix of a BTI LK2K pi I had to UN-Modify
from WARC for a customer. Used a 3CX1200 Jug.

[w4bfs]

humble suggestion:

On a big tank like that, a small strip of copper can be wrapped/formed around the tank wire and tightened with a little screw like a 4-40, the tab being soldered to wire braid going to the switch. The tightness could be improved by a comparatively large-ish brass washer on each side of the folded-together strip.
When taps are in satisfactory places, solder them in place.

be sure all hardware is brass otherwise may heat up and loosen

[N2DTS]

The coil in that amp looks melted...

[W9ZSL]

Got the AirDux today.  It is identical to the one used in the KW-2 amp from the 1962 Orr Handbook.  This should do the trick.  For starters, I'm just going to set up for 80 meters then add taps as I go along.