[Collins] low out on 17 meters

[Dr. Gerald N. Johnson]

Getting maximum power out of the PA will require moving the loading 
control to a lower value that the 50 ohm mark. But the problem may be 
low drive to the PA also. Check that to see if you can drive PA grid 
current in the tune or CW position up like it does on 15 meters.

If you can't get the PA grid current on 17 meters its probably a sign of 
not quite perfect tuning rack tracking. That tracking is set by the 
relative slug positions and is less critical on the bands with each 
having adjustable trimmers. The complete cure is to do a complete rack 
alignment starting with preset capacitor positions on 80m and peaking 
the slugs. The trouble with such a complete alignment is that there's a 
fair chance of some capacitors being stuck and so not readily adjustable 
without a whole lot of work. I think what I'd try is to work with only 
the band D trimmers and try to find a setting of the capacitors that 
allows decent drive on both 17 and 21 MHz adjusting the rack knob for 
each band. This is compromising the tuning, not fixing the tracking, but 
fixing the tracking can turn into a excessive amount of work with some 
stuck trimmer capacitors.

I suspect the 17 meter tracking can be improved on from that book start 
on 80 meters with the trimmer capacitors set to 2/3 C, but each tweak of 
slug means a total realignment. Typically to make tracking circuits 
track we adjust the slugs at the LF end, and the capacitors at the HF 
end and they interact. If I was going to do that, my LF would be 17 or 
14 MHz on band D and my HF would be 21.4 or 21.6 MHz still on band D. 
Then with the tracking worked up, for those bands, I'd have to adjust 
the trimmers on 80m contrary to the book's instructions and on all the 
other bands.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 6/23/2011 9:33 AM, yash at aol.com wrote:
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>   The max I can tune on 17 meters is around 60 watts  75S-3/32S-3,  the 17 meter crystal is in the D-1 position and the receiver is controlling the transmitter. tried moving the crystal to transmitter,no change.Is there a solution for 17 meters or is this the nature of the beast?
> thanks for any help on this.
> 73 dale wt4t
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