CPI CP2000 power balance issue

[Crambone]

Ok guys I finally got the CP2000 working but I’m having an issue balancing power output across all channels. I followed the procedure in the service manual but it gives the same result. I’m showing 4 watts on channel 1 but when I go up in channels the power rises a bit on each channel till it maxes out a 7 watts on channel 20 then it slowly drops back down as I continue to channel 40 4 watts.
I thought maybe The power variation (4W on Ch 1, 7.0W on Ch 20, 4W on Ch 40) is due to the bandpass filter (L202, L203, L204) and output filter (L201, L205) being tuned for maximum power on Channel 20, creating a resonance peak. Retuned but same results.
I also checked BIAS on the driver Q101 and Final Q102 and that checked good and I’m glad as the use fixed resistors to set BIAS.
I then tuned a bit different from the service manual, still unbalanced, slightly detuned L203 (mid-band inductor) to reduce the Channel 20 peak, then re-peak L204 (Ch 1) and L205 (Ch 40) to recover edge power. I did get it a bit closer playing with the adjustments that way now channel 1 = 4watts, 20 = 4.7watts, 40 = 4 watts.
Has anyone else ever experienced this? It’s a pain in the @ss to follow the schematic and identify the components on the boards and the service manual dosent have a parts layout diagram.

Thanks, Andrew

 

[nomadradio]

The call it "stagger tuning". Typically one coil of a two-coil bandpass circuit gets peaked below the center of the band, the other one above the center. Back in the bad old days of 23 channels, a radio with an outboard VFO would be troublesome in this way. Going to an extreme, peaking one coil above 23 and the other one below channel could get you a "dip" in the frequency response, with more power on channel 1 and 23 and less on channel 12.

But it's a by-gum and by-gosh procedure to get it broad banded. Sounds like you're on the track.

73