[Premium-Rx] WJ 8888 1st LO problem

[Peter Rovardi]

Hello all,

Wonder if any WJ people out there could possibily advise on a problem I,m having regarding the 1st LO on my 8888.

This started when the RX appeared to be suddenly disconnected from the antenna, leaving full audio present and all controls working normally, including tuning and display readout.

Fault finding first with BP & Sub filters, then finding that the 1st LO Input (J4 on the Input Convertor module) was stuck at a frequency of 114.8Mhz, while it should run between 83.31 and 113.31Mhz on tuning.

I then tested the RX by sweeping a -20dBm sig. across the proper frequency range into J4, and it works fine.

Output from the 1st VCO (Type:-791271) @ 114.8 Mhz appears to have the required output power level.

I then finally found that the 1st VCO Time Base (Type:-791109) had its Tuning Voltage output stuck at minus11.8v DC.
(I think it should normally run between minus10v to +10v DC for the full tuning range)

Just looking at this board is a bit daunting.   I am hoping to keep component removal to a minimum.
As the board is fully lacquerd, I am seeking any advice on what components to remove and check first.  This  would be greatly appreciated !.


(and / or if anybody has a spare board they could possibily part with, please contact me directly)

Many thanks,
   Peter Rovardi  G4HSB.