[R-390] Testing the 2nd osc, swapping xtals

[dog]

Today I turned on #1 RX and started swapping crystals, but first a tube 
that produced -XVDC in RX2 produced more volts in RX1, so that is 
something. But I started swapping xtals, especially the ones that were 
quite different between the 2 RX's of which there were only a few. There 
was only one position that swapping a crystal made a significant 
difference and that was at 31MC. The 2nd osc went from 4.5 to 7.5V. But 
notice that the same crystal is used at 14MC. It made no difference 
there so WTF? In general I would have to say that swapping crystals is a 
crap shoot at best and not worth it in my RXs. I'm not sure if it's 
components in the output circuit of the xtal osc, the osc circuit itself 
or what. I'm about to just go and shotgun the worst 2nd osc (#2) 
starting with the tube circuit itself. Not sure how hard it is to get 
into the output circuits with the tuned caps. I'll see when I take it off.

Also there was a general tendency in RX1 to have lower voltages at 8MC 
or lower freqs and higher outputs at higher freqs, just like RX2. But I 
did have one that was 2V at 24MC and swapping the crystal made no 
difference. All tuned circuits had 2 max points and they were not 
exactly opposite. I wonder if I can see underneath where max and min 
would be on these var caps so I can tell easier from the top what 
they're doing.

I wonder if it was a progression of building receivers that someone came 
up with this mixing scheme or if it was laid out from the design of the 
thing. It reminds me of when I used to work for the PO on the letter 
sorting machines, they could put letters in the 'delivery point' sorting 
machine and in 3 passes have all the letters in order for a delivery 
point on each road and the letters sorted up and down the street so the 
delivery guy didn't even have to sort stuff. He just had a box of 
letters for each street, presorted, and had to go up one side of the 
street and down the other. What magician figured that out?

I haven't addressed the 20V that's still on the 1st osc in RX1. I may 
first do some 2nd osc tube voltage/ohms measurements before I get too 
far. Is this exciting or what? Maybe this says something for swapping 
out all the mica, coupling and bypass caps and measuring the R's from 
the start while it's apart.