[AMRadio] 3-500Z @ 4 kV (Was: Johnson trannies...)

[Rob Atkinson]

Hi Kim,

I probably had incorrect information or did not remember it
accurately.  Sorry about that.

73

Rob
K5UJ

On Sat, Jun 4, 2011 at 3:21 PM, Kim Elmore <cw_de_n5op at sbcglobal.net> wrote:
> I changed the subject line so as not to continue committing a thread hijack.
>
> I never looked into the IMD characteristics before I did this, to be
> honest. Almost all my operating is CW, so that doesn't so much matter
> to me. But I looed at the the spec sheet I have (c 1980) and it says
> that 3rd order IMD is -40 dB at 3.5 kV and 5th order is -45 dB.
> Nothing is listed for 5th order below 2.5 kV, so it must simply be
> below -46 dB. The best 3rd order appears to be at 1.5 kV, where it's
> -46 dB. Third order IMD increases to -33 dB at 2.5 KV, then stays
> steady at -40 dB for 3.0 and 3.5 kV, where the table ends. Under load
> (400 mA CW) I see about 3.6 kV B+, but with SSB or a two-tone test,
> it's closer to 3.8 kV. Originally, the B+ dropped to about 2.7 kV
> with 400 mA CW and was up around 2.9-3.0 kV with a two-tone test. It
> may well be that the IMD isn't as good as it was, but probably isn't
> too much worse.
>
> I can do AM with the amp and my Orion II, but I'd rather do AM with
> my Dad's Globe Champion 350, but have a problem somewhere between the
> VFO and the AX-9909 finals. Jim Wilhite and I have looked at it and
> we're still scratching our heads as to just what's going on. I
> strongly suspect that my problem is self induced, but for the life of
> me can't find what I've done to cause it.
>
> The VFO is fine and doing exactly what it's supposed to do with the
> output amplitudes it's supposed to have. It's somewhere in the 6CL6
> buffer or 2E26 driver. The symptoms are strange: there's no drive for
> 40-10 m and it doesn't act right on 160 and 80 m, either. Resonating
> the grid no longer gives me the big peaks I remember. There's always
> a background grid current of between 5-10 mA, and the peaks are not
> the pin-bending amounts the rig had before I got into it. This Champ
> has never "liked" crystals (slow to take off, if at all), but I have
> a couple that work on 80 m. These act exactly as I'd expect, but when
> I use the VFO, things change for the worse. But, Jim and I have gone
> over the VFO and it seems fine in and out of the rig.
>
> If there are any other Globe Champ 350 aficionados out there that
> have experience with the rig, I'm all ears!
>
> Kim N5OP