Back in the late 1970s and early 1980s, I worked on Motorola IMTS
synthesized car phone radios. This was before plated through holes in
PC boards were reliable. So, the Big M used eyelets, instead. The
solder in these would crystalize and the synthesizer would be producing
all sorts of wrong frequencies. I made a decent living resoldering many
of these boards for some years.
73,
Steve WA9JML
On 7/6/2015 7:46 AM, Jim Allen wrote:
I'm glad you found the fix.
Why is it there are so many re-solder fixes these days. I don't recall ever
hearing about resoldering on the old gear. Anybody ever have to fix a 75A4 or
SX101, etc. by resoldering some connections?
73 de W6OGC Jim Allen
Sent from my iPad
On Jul 6, 2015, at 7:39 AM, Joe Papworth via TenTec <tentec@contesting.com>
wrote:
It appears to be fixed and in repairing it, I fixed another annoying problem,
which was spurs and floaters on ten meters only. Those had been plaguing me for
several years.
First, thanks to Paul at Ten Tec for pointing me in the right direction and to
Mark, K8VF, and others for their suggestions.
Paul was right. The problem was on the Xtal Osc/LO board. The repair process
went like this:
1) I looked at the schematic of the board and saw there are 4 separate xtal
? ? oscillators for ten meters (I assume one for each 500 Khz band segment)
? ? Since I was losing the entire band, I knew it wasn't one of those circuits.?
? ? That eliminated a lot of circuitry as a possible cause.
2) After reading the theory of operation, I pretty much narrowed things down ?
? to the L9, L10, and L11 circuits, plus the Q4 and Q5 circuits.
3) I resoldered every component in those areas and voila, no more spurs or
? ? floaters and so far, RX and TX are fine. (I'm fairly certain the rig would
? ? have failed?by?now)
Later, Joe
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