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G8MNY > TECH 17.09.14 12:20l 52 Lines 2421 Bytes #999 (0) @ WW
BID : 10413_GB7CIP
Read: GUEST
Subj: IC 735 No RF Output Fault
Path: IW8PGT<IZ3LSV<IR1UAW<IW2OHX<UA6ADV<GB7CIP
Sent: 140917/0830Z @:GB7CIP.#32.GBR.EURO #:10413 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New June 14)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
________________________________________________________
³ ŚÄÄÄÄÄÄÄÄæ ŚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄæ == == == ³
³ ßßßß == ³ \ ³ ³ Rx 14.273.5 vfo A 12³ _ _ ³
³ /~\ ĄÄÄÄÄÄÄÄÄŁ ĄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄŁ (_) (_) ³
³ \_/ ____ IC-735 ³
³ ßßß ~~~~~~""""""~~~ /' `\ ßßß /"~"\ [] ³
³ 0 ÜÜÜ |(~) | ÜÜÜ | | ³
³ Ž Ž Ž Ž Ž Ž ³ ~ ³ \._./ [] ³
³ /~~\ ßßß Ž Ž Ž Ž Ž Ž | | ßßß == == == ³
³ \__/ ÜÜÜ # # # # # # [] \.____./ ÜÜÜ [___] [___]³
ĄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄŁ
I have 2 of these old rigs, one for /P use & training courses, and a clean one
in the shack. I've been looking into a problem with my older well used IC735.
It developed this fault while in use on a /P demo HF station.
Initially it looked like it was something to do with the rig's rear Rx phono
patch lead. But it turned out to be the nearby SO239, where the centre pin is
allowed to float to make good connections. The thin hard wire used in the PA
box to the filter PCB had broken due to this small movement.
Indicating clues to this fault's whereabouts, were the rig's O/P SWR meter
shows power & infinite SWR. but external kit showed no power.
Access is fairly straight forward, but a lot of screws!
1/ Remove power lead, remove top & bottom covers including the anti rattle 4
around the LS.
2/ Unscrew the 4 screws for PA unit, remove external Phono Rx patch lead,
release LS lead, RF drive lead from underside PCB & 2 other connectors to
the upper PCB. then rotate the PA unit.
3/ Remove all the screening plate screws & lift it.
4/ Inspect the aerial socket. If broken as mine was or loose in PCB continue,
or go to 8/.
5/ Remove the filter PCB (loads more screws) unsolder Rx phono wire & earth.
6/ Replace the hard wire link with fine flexible multi-strand wire. (I kept the
insulation tube)
7/ Put back the PCB & solder up, check the slight SO239 pin movement will not
break the new wire.
8/ Reassemble & test.
Also see tech bul "PA instability in ICOM IC735" & "Autocaller with old Maplin
kit"
Why don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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