Bendix/King ADF-T12C ?

[Henry Kolesnik]

A freind has asked me to see if I can find any info on the subject aircraft
radio that covers 190 to 1750Kc in 3 bands. A schematic and IF frequency
would be nice. I can't find anything Googling.
tnx
73
Hank WD5JFR

[K3HVG]

The Bendix ADF-T12-series direction finders are the Bendix
transistorized version of the old Motorola ADF-12. Any General Aviation
radio shop will have a book on this radio. The I.F. frequency is 140
kHz. The schematic set is a bit involved to scan, but the rear panel
Amphenol Blue-Ribbon connector pinout is as follows:
Pin 1 Sense antenna
Pin 2 Loop shield
Pin 3 Loop Input R1 (Tin)
Pin 4 Loop Input R2 (Copper)
Pin 5 Optional Audio Amp A+
Pin 6 Dial Lamps
Pin 7 Tuning Meter (ext)
Pin 8 47Hz switching Phase 2
Pin 9 Ground
Pin 10 Servo DC Output
Pin 11 Spare
Pin 12 47Hz switching Phase 1
Pin 13 Servo DC Output
Pin 14 Headset (500 ohm)
Pin 15 DC In +
Pin 16 ADF Servo Signal Output

The manual set I have is for the ADF-T12D with synthesized tuning. The
12B and C are infinitely more reliable than the D-model.. which is a dog!!!

Good luck with the project. de K3HVG

[K3HVG]

Let me also add the following... In order for the system to function,
one would need the 2321E loop antenna, the special (balanced)loop
antenna cable set, and any of the 551-series servo amplifier/indicators.
Without these items, one simply has a LF/MF receiver. For listening,
simply connect A+, ground, headphones, and a wire antenna to the sense
antenna input. Input voltage (12v or 28v) is rear-panel selected. No
internal changes are required.

[Henry Kolesnik]

Thanks, I've forwarded your notes to Karl DC2RU, he may be in touch..
73

--

73
Hank WD5JFR
"K3HVG" <je...@adelphia.net> wrote in message
news:6_WdnUqlIL7aGi7Y...@adelphia.com...

[RapidRonnie]

> 73
> Hank WD5JFR
> "K3HVG" <je...@adelphia.net> wrote in message
> news:6_WdnUqlIL7aGi7Y...@adelphia.com...
> > Let me also add the following... In order for the system to function, one
> > would need the 2321E loop antenna, the special (balanced)loop antenna
> > cable set, and any of the 551-series servo amplifier/indicators. Without
> > these items, one simply has a LF/MF receiver. For listening, simply
> > connect A+, ground, headphones, and a wire antenna to the sense antenna
> > input. Input voltage (12v or 28v) is rear-panel selected. No internal
> > changes are required.

Many of the old tube ADF sets were repurposed for boats years ago and
they did not hold up terribly well especially on salt water. Both the
Motorola/Bendix and King Radio units are very desireable for BCB DXing
today. Avionics shops will sometimes give you them if you ask properly
along with old dynamotors and such.