Re: {Collins} Antenna tuner question

Thanks Roy.

We have a 180L-2 in the museum, but it isn't featured on the museum website
(Rockwell Collins Museum) except for a listing in the early products

The 180L-2 and 180K-3 are shown as part of the 18S-4A system.  They are
referred to as antenna tuning units while the 180V was called an antenna
coupler.  18S-4A was a 100 watt 20 channel crystal controlled AM transceiver
with a mechanical filter.  The 18S preceded it and 500 radios were sold to
airlines in 1947.  The 618S was capable of 200 channels and then the 618S-1A
had SSB capability; don't think there were very many of the SSB versions
delivered before the 618T took over.  I think the 180L-2/3 may have been
used with the 618T but since it is a 400 watt rig, wonder how that worked
out.  I have some 490T couplers and they sometimes arc and spark with 400
watts even though they are rated for that power.  

Interesting that someone posted the pdf of Maxwell's Reflections.  I was
amused by some of the heated exchanges in QEX magazine between Walter and
Warren Bruene regarding conjugate matching. 

Suggest that anyone interested in couplers read my friend Glenn Snider'
Chapter 15 on Antenna Matching in Sabin and Schoenike's  "HF Radio Systems
and Circuits".  

Jim w0nkn
-----Original Message-----
From: Collins []
On Behalf Of Roy Morgan via Collins
Sent: Wednesday, October 11, 2017 2:53 PM
To: Jim Pruitt <jpruitt67@xxxxxxxxx>; Collins <collins@xxxxxxxxxxxxx>
Subject: Re: {Collins} Antenna tuner question


It is the 180L-2 or 180L-3, depending on whether the thing is equipped with
the antenna changeover relay or not.  (Yes, the 180L-2 and 180L-3 differ in
that the L-3, I think, has the antenna relay).

One problem with these things is that they require 24/28 volts to run most
things in there (2 amps) but also need 115 volts 400 cycles to run the phase
detection system that is essential for it to operate.  This voltage needs to
be of low  power only, it is not used as far as I remember to run anything
but the detection circuitry.  60 cycle power will not do the job!
The web site shown below indicates 15 watts.

The antenna relays are more than somewhat fragile, as is the vacuum
capacitor that is in there.  Dropping one of these quite heavy boxes is both
a danger to your toes, but also a danger to the relay and the variable
capacitor.  If your tuner rattles with broken glass, and it is the
capacitor, give up all hope of getting it to run.

Note that they are meant to operate in aircraft, so at altitude the
breakdown voltage requirements of the various parts influenced the design a
lot.  So... you may well be able to manage more power at normal human
altitudes than it was meant to handle at altitude.

Note also, the antenna it was meant to tune was quite short electrically (at
least for much of the HF frequency range - 45 to 100 feet) compared to what
a ham operator may have.  Just the same, if you can get one running, I'd
expect you wold be quite impressed with its performance.

These may have been used with the ART-13 transmitter, I'm not sure.  There
is an indication they were used with the 618S-1 and 618S-4 transceivers.

You can read a moderate amount about this magical box at:

That site includes a circuit diagram but neither the text shown nor the
diagram tell the name of the manual they are from!
A request to the Collins list in 2008 brought no responses.  I am sure there
is or was a manual for these, but a quick web search brings no other good

Note: tuning an antenna AT the antenna feed point with a remote antenna
tuner, is simply NOT required. Search for and read (if you can) Reflections
III for full details.
Buy one for $183 on Amazon at
or search the web for the PDF version I was able to find some time ago (not
easily just now).

I"d be glad to learn of a source for the military manual for the 180L-2 and


Roy Morgan
k1lky since 1958

-----Original Message-----
From: Collins []
On Behalf Of Jim Pruitt via Collins
Sent: Wednesday, October 11, 2017 12:41 AM
To: collins@xxxxxxxxxxxxx
Subject: {Collins} Antenna tuner question

Can someone tell me the Collins model number of the antenna tuners that used
a motorized roller drum with silver plated ribbon
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