> I do have a signal generator and return loss meter that is accurate up
> to 1 Ghz so this is what I was attempting to use.. Thanks for the
> tips, I'll give it another stab (now that it's easy to switch between
> the two tubes.)
>
> thanks,
> Paul
Tube installed (no extra load resistor) Lid on and all screws in and
secure, no power in any way connected.
Feed your sig-gen or sweeper into the PA Output jack, via a 10dB (at
most) attenuator then the return loss bridge. The resonance will be
obvious.
The 10dB pad is to stabailse the impeedance the sig-gen sees, so you get
consistant results. Have that loacted at the end of the cable by the RL
bridge, that is itself fitted directly on the amp's PA deck output
connector. You will of course have to turn up the sig-gen output to
compensate for the loss of the attenuator.
Idealy, a nice VNA is what you'd use, but a simple tunable sig-gen or
sweeper will do the job just as well.
Note, the dip in VSWR can be very narrow and not so deep as you expect,
so tune slow and carefull.
Enjoy.
Dave G0WBX.
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