AWA 25M-22 (E-band) Conversion Mods for 6 metre Amateur band

Created 24th October 2001

 Modifications to an AWA Carphone model 25M/22 to convert its
operation from commercial VHF low band to 6 metres HAM band
This is the newer version of the AWA 25M/1, basically a
different TX P.A. unit.
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RECEIVER:

XTAL freq = (Operating freq + 10.7 MHz) / 2

Remove and bypass the receiver input filter.
Change C1 to 33pF (polystyrene)
Change C6 to 39pF (polystyrene)
Change C8 to 39pF (polystyrene)
Adjust slugs in TR1, TR2, L1 & L2 flush with top of formers
Adjust slugs in L3 & TR3 to protrude 3mm above formers
With voltmeter on TP1 & 2 adjust TR2, L3 & TR3 for maximum
(0.1 volt typical)
Apply a signal to receiver and adjust TR1, L1 & L2 for maximum
signal (mute should open @ -120dbm or .22 uV)

TRANSMITTER:

XTAL freq = Operating freq / 18

Change last tripler stage (VT7) to a doubler by adding 47pF
across L6 and 47pF across C55  (polystyrene capacitors)
Peak up exciter for maximum RF out (40mW approx)

PA STAGE:

Rewind L1 using wire of the same guage. 15 turns on 5mm dia.
Rewind L4. 4 turns of 1mm wire at same dia.
Rewind L7. 4 turns of 1mm wire at same dia.
Rewind L8. 3 turns of 1mm wire at same dia.
Rewind L11. 4 turns of 1mm wire at same dia.

ANTENNA FILTER:

Remove filter and unsolder lid
Remove ALL coils and rewind using 1mm wire
L3 & L4  10 turns at 5mm dia. close spaced
L2 & L5  9 turns at 5mm dia. close spaced
L1 & L6  7 turns at 5mm dia. close spaced

Tune PA for maximum RF output (40 watts approx)


Thanks go to Laurence Adney VK2ZLA for this information.
See you on six. (52.525 MHz)

73 de Dave VK2GHZ @ VK2RWI.nsw.aus.oc


NOTE: only licensed Amateur Radio operators can operate this modified equipment on assigned Amateur frequencies/bands.

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