[R-390] Capehart made R-390A Serial #312

[Jacques Fortin]

Hello Karsten,

Can you explain how do you probe the oscillator output ?
It is a connection to your frequency meter that use any coaxial cable ?
What is the input impedance of the frequency meter ?

Sorry to ask, but maybe you did not figure the implications: if any
additional capacitance is introduced in the 2nd crystal oscillator
structure, this will add to the C431H in the V401 circuit, then probably
preventing the oscillator to work on the 3rd harmonic of the crystal.
BTW, to answer a question asked by Larry Haney, the 31MHz band probably
works OK and that is because the stage works in doubler in that band (2 x 17
MHz).

Are you trying to "tune" the Xtal outputs to the "right" frequency by using
the frequency meter, or did you use it just to confirm that the oscillator
is working on all ranges during the alignment process ?
>From the Y2K-R3 alignment instructions, nothing specifies to do so.
The "trimmer adjustment"  instructions in the section 6.2.9 should be
followed without connecting anything, except the 2nd mixer, to the 2nd
crystal oscillator output !

73, Jacques, VE2JFE in Montreal

I am currently working on realignment: checking and tuning Crystal
Oscillator subchassis. Frequencies measured with an accurate  8-digit
digital counter. Everything appears to be ok. One exception: oscillator
output on band 30 is 22 MHz (2nd harmonic), should be 33 MHz (3rd harmonic).
Active crystal is Y403 (11 MHz). Trimmer capacitor C431H appears to be ok.
Output (pin 3 of T401) is in the range of 3 to 5 volts and can be adjusted
by turning C431H. Band 8 (11 MHz osc. output) is ok. Band 19 (22 MHz osc.
output = 2nd harmonic) is ok. Any ideas why band 30 output is 2nd harmonic
and not 3rd?
Regards
Karsten