An Aircraft Transmitter of unknown type...

(16-Nov-2002)
tx notes.  (what am I?)

a ? anywhere in the following notes indicates an un-readable 
number or letter, possibly due to corrosion, or other damage.
Or a best-guess of the component / stage it relates to.
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1A,2A,3A,4A,5A,1B,2B,3B,4B,5B,  to select in frequecy-order.

the crystal frequencies (in the 5MHz area), start to make sense 
when multiplied by nine the range then becomes 51.1 to 52 MHz in 
100kHz steps, although the final working frequencies could be 
higher than this.  The unit looks like a piece of aircraft kit.
probably civil, rather than military.
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unit  is about 14 inches deep, 5 inches wide, and 7 inches high.
if I had to date the unit, I'd say mid to late 1950's
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the top-back of the unit contains a rotary converter mounted 
across the case. it has a small label, and a rating-plate.

the metal label says....

         K.L.M.
      No 74622 098

the ratings plate says...

 TYPE  MP-42D  POWER  SUPPLY
 SERIAL 261     WT 3lbs  0oz
   INPUT 28.0V    1.4AMPS
  OUTPUT 220v   .0?? AMPS
       BENDIX  RADIO
???? OF BENDIX AVIATION CORP
    BALTIMORE  MD  USA
          MADE BY
    RED BANK  DEVISION
   RED BANK  NEW JERSEY
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the front panel has a UHF/SO237 rf connector, plate mounted (4 screws)
on the upper left-hand corner.  beneath this, and in the centre is a
small aluminium plate. plate says...:-

             D.F.G.
           No    006

under this plate, running horizontally is a handle.

under the handle, to the left hand side is a 1/4 inch jack-socket "TEST"

under the handle, to the right is a black wiring terminal marked  "G"

on the bottom left hand corner of the front panel, there is an aluminium
14 way plug, chassis mounted by four screws. retention of the socket
looks to be by screw thread, about 1 1/4 inch dia about 18TPI

to the right of the chassis-plug is a plate, removable by three screws,
under this are two variable-resistors,  left is marked "sensitivity" and
has a scale from 0 to 10.  the right hand VR is marked "centering"
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the left-hand side panel (viewed from front) is removable (13 screws)
under this panel are many descrete components, along the bottom are a
group of four metal-cased capacitors, and in the middle-bottom is a 
"D 167020 varistor"

above these is an eight inch long tag-strip. containing various 
resistors/capacitors.

above this is the screening can of the oscillator unit. the cover is 
removable (4 screws) inside are five large, and one small relay for 
switching the crystals (2 banks of 5)..
The underside of two valve sockets. and the various other components.

the windings on the inductors on the oscillator valve, and the following
valve seem to indicate that frequency-multiplication is likely to be 
occuring in these stages. possibly to high HF or low VHF frequencies.
------------------

------------------
the right-hand side panel (viewed from front) is removable, (4 screws) 
this panel has  "TUBE COVER"  pressed into it in large letters.

under this cover are the valves, crystals, transformers, and other large
components.

along the bottom are, from left-to-right. ...
output trans KS8727  (thordarson electric mfg co) large unit
RET KS87?0 (small unit)
RET KS8729 (small unit)
output trans KS8726  (thordarson electric mfg co) large unit
output trans KS8728 (small unit)

above these, from left-to-right are. ...
transformer can?  120-1  690312
metal-cased, octal based valve. RCA 12SG7 (VT209 marked near socket)
transformer can?  120-2  690312
metal-cased, octal based valve. GE JAN-CG-12SG7 (VT209 marked near socket)
transformer can?  121  69031?
glass-tube, octal based valve, philips 12SQ7GT (VT104 marked near socket)
metal-cased, octal based valve. RCA 12A6  USA VT-134.  VT134 marked near 
socket. 

metal can, three terminals can be seen undeneath (viewed from LH cover)

above these, are a further six valves, fout of these appear to be in the
RF part of the circuit. the right hand pair appear to be non-RF.

starting in the top-left corner, then mid-left--to--right.

valve small mushroom shaped glass top with octal base. western electric 717A
VT-269, has VT269 marked near it's socket, has some small variable inductor
coupling it to the aerial socket on the front panel.

valve small mushroom shaped glass top with octal base.raytheon JAN-CRP-717A
VT-269, has VT269 marked near it's socket, has two small variable inductors
one coupling it to the output stage, the other to the driving stage.

valve small mushroom shaped glass top with octal base. western electric 717A
VT-269, has VT269 marked near it's socket, the base of this valve is inside
the screened oscillator can (in LH-side cover) is has two small variable 
inductors connecting it to the driver-stage, and another two small variable
inductors connecting it to what looks like the oscillator valve.

valve glass-tube, octal-base. JAN-CKR-12AH7GT KEN-RAD USA  VT-207, has VT207 
marked near it's base, the base of this valve is inside the screened 
oscillator can (in LH-side cover) is has two variable inductors, and appears
to be connected to the crystal switching relays. it looks like an oscillator.

metal-cased, octal based valve. KEN-RAD USA  JAN-CKR-12SR7   VT-133  SC961A
it has VT133 marked near socket.

glass-tube, octal based valve, National Union Electron Tube 12SR7GT it has 
VT133 marked near it's socket.

above this valve, is a transformer can?  122  690350, and to it's right, 
a metal cased component which looks like a capacitor.

to the left of the transformer?, above the two oscillator/multiplier valves,
and to the right of the output/final valve. Is the bank of crystals. They 
plug into sockets, and have a tin-plated screening plate between them and 
the valves they're closest to. The crystals are held in place by a retaining-
bar with sliding catches. they're in "FT243" type crystal holders, the freq's
are marked in kHz. From left-to right, thier socket number, marked frequency
& other info.

1A  5677.777     date 8-26-54
1B  5733.33      channel W (for use in radio receiver BC-733-A circuit of 20MMF)
2A  5688.888     date 8-26-54
2B  5744.44      channel V (for use in radio receiver BC-733-A circuit of 20MMF)
3A  5700.00      channel V (for use in circuit of 20MMF)
3B  5755.555     date 8-26-54
4A  5711.11      channel W (for use in radio receiver BC-733-A circuit of 20MMF)
4B  5766.666     date 8-26-54
5A  5722.222     channel Y (for use in circuit of 20MMF)
5B  5777.777     date 8-26-54

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end of unit description. end of document
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