I tried to do the adjustment procedure for A20, but could not get the YTO frequency above about 2.1 GHz, and likewise with any settings of the SA. Fortunately I have on hand a nearly full parts carcass, so I found by board swapping the actual fault appears to be on A19, the DAC pre-tuning board. Now the unit has original A21 and A20 (but all messed up from trying to tweak it before), and a different A19, that all now seems to work. The A19 is a different board version - I don't know if it's newer or older than the original here, but it should be OK.
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I'll have to try the whole procedure for tweaking it up, unless I can quickly find and fix the fault in the original. Now that I know where to look, I will poke around in there and see what's up.
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Ed
