Some HW-16 problems...

[Bill Turner]

On Tue, 30 Sep 1997 17:05:33 -0700, Ken Gordon <keng at UIDAHO.EDU>
wrote:

>Picked up a basket-case HW-16 about a year ago. When I got it working the
>FIRST time, it chirped with crystals, but not with an external VFO (VF-1),
>and had a T-5 note on 80.
>
>One or more of the filter caps shorted one day and took out two of the
>"filter" resistors in the filter string, so I replaced the caps with
>Nichicon 470 ufd @ 450 vdc, the resistors with a 6 Hy filter choke,
>and installed two VR-150s. Rewired the tx osc. stage to put regulated 150
>vdc on the screen and regulated 300 vdc on the plate, and, while I was at
>it, used regulated voltages for all the receiver except the audio amp
>plate.
>
>Still chirps with crystals, but the note on 80 is now T-9 and it puts out
>nearly 50 watts on all three bands.
>
>Anyone have any really bright ideas concerning how to stop the chirp
>without eliminating the QSK (such as it is)?
>
>I also had to parallel the 150 pfd cap (which is switched across the final
>tuning cap for 80) with another 12 pfd to get the final to tune at the low
>end of 80.
>
>Ken W7EKB
>
_______________________________________________________________
Assuming the regulated plate and screen voltages to the oscillator
really are regulated during keying, one other cause of chirp is
excessive drive to the crystal itself which can cause it to slightly
overheat each time it's keyed on and off.  Try reducing the feedback
within the oscillator so it just barely oscillates reliably.  One way
to do that is to reduce the plate and screen voltage.  Another is to
add an unbypassed resistor in the cathode lead - start with a low
value like 10 ohms or so and increase it until it won't oscillate
anymore, then back down.  There are no doubt other ways depending on
the circuit.


73, Bill W7TI

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