GO-9 Radio Set

The GO-9 was made by Westinghouse in 1940 for the US Navy, employed in CW
and MCW modes in certain Navy aircraft. It was given to me by Rick
Christensen KA7CHT somewhere in the early 90s. It was given to him a few
years previous by Dallin H. Oaks, then president of BYU (now an Apostle
in the LDS church). I was intrigued by its beefy construction and the
nice coils and varaiable caps inside it, even entertaining thoughts of
cannibalizing it, but couldn't bring myself to do it, so it sat around my
basement for years. It was missing all of its complement of three tubes,
namely two 837s and an 803. Sometime in 2002, I bummed an 803 from Andy
KC7KW, and after plugging it in and lighting the filament, I knew I had
to try to get it working. I looked around for data on it, got a
schematic from a ham I ran into on 40 meters, then discovered that I
already had an old WWII surplus radio conversion manual which contained
all the info I needed. From the beginning of my labors, I opted to leave
it as original as possible. Someone had already installed a filament
transformer for the 803, which I left in place.

Meanwhile, I happened to acquire the RA-62/SCR-274 "Rectifier" from Harry
Temple WD5CFP, and despite its somewhat rusty, ragged appearance and
ponderous weight, found that it was practically made to order to provide
the 400 volt low B+, 12 volt filament, and negative 100 volt bias
voltages (for keying). I had originally intended to employ blocked-grid
keying, but after reading an article in an old ARRL handbook showing how
to key the screen of the final and the plate of the driver, I tried it
and (after regulating the low B+ with VR tubes) it worked fine, so I left
it that way. The existing negative 100 volts which I would have used for
the blocked-grid keying was also used to actuate a relay in the RA-62,
and since the keying circuit I chose called for a keying relay, it was a
perfect fit. (This approach left me with 100 volts DC on the contacts of
my bug, so I don't do much contact adjusting with the power on, but the
contacts stay nice and clean.) That took care of everything except the
high B+ voltage.

A few years back, Doug WB7TUJ had given me a salvaged paging transmitter
which contained a solid state 2400 volt supply, which I trimmed down a
little, re-mounted its components on an aluminum-covered piece of plywood
cut to fit inside the top of an old milk crate, which in turn served as a
cover to keep cats and kids from getting zapped by the high voltage.
That unit met my high voltage needs very nicely. Since my piece of the
GO-9, the HF unit (the complete installation consisted of an LF unit on
the left, a power supply/control unit in the center and the HF unit on
the right) was made to attach to the side of the power supply/control
unit in the US Navy installation, I needed to make an add-on chassis (not
complete in the photos--the side, top and bottom panels were not done
yet) for mounting the necessary switches, power cables, antenna relay and
connectors, meter(s?) and VR tubes, leaving room for a future
suppressor-grid modulator addition (which I have breadboarded and
tested). After some careful measuring and marking, a shower of hot chips
from my table saw, and considerable punching, cutting, filing, sanding
and painting, I had the panels I needed.

I have made several CW contacts with the GO-9, mostly on 40 and 80
meters, and get a big kick out of firing it up (especially in the dark)
and seeing it work. It is rather stable for such an old design, and has
just enough slight wiggle in its frequency to give it character. It puts
out about 200-250 watts (the US Navy only asked it for 100 watts) and
covers from 3.0 to 18.0 mHz, and will tune an ordinary low-impedance
antenna, such as a dipole, or a random length wire (trailing wire
antennas were commonly used on the PBY and other WWII aircraft).

Prior to receiving the old beast, I had never heard of a G0-9, as it
seems is the case with most everyone I know. While I was doing the mods
on it, I discovered a military radio collectors group on the internet,
which resulted in getting the picture of the complete setup and the
copies of the PBY Catalina manual, before which I had no idea where or
how it was used. It is a rather strange animal for several reasons. It
is HUGE for an airborne piece of equipment, measuring approx. 23 by 12 by
16 inches. Also, it used 800 Hz AC as a power source (400 Hz became the
standard shortly after its time), and for MCW mode, they simply
disconnected the filter caps in the high voltage supply and let the 1600
Hz pulsating DC modulate it. I would imagine that some of the other big
flying boats might have used it, but have no actual knowledge of that.
Any further info on it, or on any other use of 800 Hz powered gear will
be gratefully received.

Dan Metcalf KO7R
ko7r@juno.com