[Boatanchors] Bendix Skipper 135: Spooky Radio Hi-Jinx on Halloween!

[David Stinson]

Halloween, and the Zombie
Bendix Skipper 135 "fishing boat radio,"
which some said had not a ghost
of a chance of resurrection, though it had
neither been staked nor stuffed with garlic,
lives!

Despite the grumblings and howlings from
assorted witches and werewolves, I applied
Black Cat Bone, Eye of Newt, Toadstool and
Solder Rosin, reciting sea shanties and Behold!
With a whiff of salty sea breeze, it arose from
the Land of Undead Radios and made its first ham
contact, saying "Boo!" to the gang on 3890 KC,
pushing my 30L1, glowing like Frankenstein
on a dark and stormy night.
https://photos.app.goo.gl/25oQLPLRXw6txKve7

Yeah, yeah ok... I couldn't resist.
On to business, because this radio
is "spooky enough" for Halloween.

The Skipper 135 is a mid-1960s hybrid "Marine" HF AM
transceiver capable of xtal-control operation from
1.8 MC to 5 MC. and, like many WWII radios, was
designed to work into an electrically-short antenna.
The receiver and audio/modulator are all-Germanium
PNP transistors.  The transmitter is a 12BA6 crystal
oscillator feeding a single 12DQ6 power amplifier with
a PI-L output network.  The front panel claims "33 Watts,"
which may be an inaccurate allusion to PEP power, since the
radio actually delivers about 25W carrier to the antenna.
I haven't scoped the output for PEP yet.
The SAMS folder which contains the Bendix Skipper 135
schematic is available at:
https://drive.google.com/file/d/1Wg1VrsNaw1jykO3srpftl4zKot0z7hKk

Unlike with historic military radios, I don't have a
big problem with *well-thought-out, informed*
modifications of radios like this to make them
functional on the Ham bands.  I've changed the
output connector to an SO-238 and added 100pFd in
series with the antenna lead to match the set
to a 50-Ohm load, removed the 10pFd trimmer from
the back panel to make room (not needed for 50-ohms),
and changed two of the xtal sockets from HC-6/U
to FT-243.  I will also be installing an aux relay
which will provide a keying lead to an external amp,
plus a switchable power buss to Programmable Oscillators/amps
for the Xmtr channels.

Here comes the "spooky" part:
Take a look at the Modulator/Audio output stage
(upper right of the diagram).
While foozilin-around, looking for a good
Prog-Osc solution, I managed to pop the Audio
Preamp Q5 and the TO-3 Driver Q6.  I had a nice
Motorola TO-3 Germanium, but my stock of small-signal
PNP Germaniums is getting kinda thin.  I decided
to see if I could make a PNP silicon, 2N3906,
work in the stage.  I plugged it in, ready
to read voltages, but the thing WORKS.
It plays with no changes, no distortion.
Later, while investigating prog-osc options
for the receiver, I accidentally over-drove Q1
crystal oscillator and popped it. A 2N3906 worked,
drop-in, no changes.  It will also work in the Mixer
stage, though not so well when plugged-in as 1st or
2nd IF amp.  Photos:
https://photos.app.goo.gl/bv3T6m5NB5TVe5Ys7
https://photos.app.goo.gl/uLxDqdgo1vgpkBLH9

Silicon working in Ge stages, drop-in,
with no degradation of performance.
Now that's spooky...
Have you any Alchemical Insights into this
mysterious happening?

Think I'll connect it to the Haunted Microphone
for some late-night October 31st skullduggery:
https://photos.app.goo.gl/RK8p1KxiDvtC8Fjf7

Still digging in The Cave for ARC-5 relays for
a list member (I've only found one- given most
of them away- but still have a couple of stones
to look under), so that's a good excuse to
dig for the aux relay for the Bendix, when
I can find some time for it.

GL OM ES 73 DE Dave AB5S


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