Without doubt this has proved to be my biggest challenge yet!
This was described as a "Spares or Repair" rig (in the U.S. these are generally described as "Tech Specials").
After an initial quick evaluation, I realised that this was a rather sick rig, and it was put on hold until I cleared other projects before returning to it.
No receive, no transmit, nothing but dots on the frequency display on all bands.
The EBay vendor, who is well known for breaking working radios into spare parts and modules (no names no pack drill!) had suggested in his advertisement that it may just require a quick tweak to restore it to health, but knowing the nature of his business I suspected that he was being rather disingenuous, or he would simply have broken it up and sold the constituent modules individually. I think he realised this was going to be a bit of a stinker!
When I eventually got round to tackling this radio a whole catalogue of faults gradually revealed themselves. The discovery of these have been documented in some detail on my blog
At the time of writing, (May 2012) receive functions have been restored except on the 10m ranges, though not yet at full sensitivity, but there is no significant power output on transmit. The issue with the PLL not locking on 10m may be cured by implementing an official Trio modification.
It appears that the radio has at some time had some liquid spilt into its innards with some consequential damage.
Faulty transistors have been found and replaced in the AVR unit, the PLL unit, the frequency display unit, and I am currently convinced that the IF unit has at least one broken amplifier stage, explaining the lack of sensitivity.
The radio has been put to one side for a while.
Here are some of the highlights so far :- (click on any image for a higher resolution version)
|AVR Unit - 2 transistors replaced|
|PLL Unit - 2 transistors replaced|
|Counter Divide Unit - 1 I.C. replaced|
|Transistors with rotted through legs! (The resistor removed for fault-finding purposes, and is absolutely O.K.)|
Having said all that, it has been a very interesting experience so far, and gratifying to make the advances described above.
This model of radio appears to have quite an interesting place in the genealogy of Kenwood radios. It appears to be an all solid state development of the TS-820S, but an antecedent of the rather more successful TS-120S which seemed to have some of the design oddities of the TS-180S ironed out.