RadioBanter - View Single Post - Marti M-30B

John Higdon[_2_] · March 14th 10, 06:29 PM posted to rec.radio.broadcasting

In article ,
(Scott Dorsey) wrote:

I am assuming that if I really wanted to reduce the power, the sane thing
to do would be to reduce the B+ voltage to the final?

Of course, there are numerous ways to trim the output stage power.
Adjusting plate voltage is one, but to avoid over-dissipating the
screen, both screen and plate voltage should be adjusted together.
Another way is to adjust the loading, as you mentioned earlier. Due to
those "sweetspot" considerations that I mentioned, the loading should
only be used for minor power adjustments during operation. As I'm sure
you are aware, stage tuning and loading go hand in hand.

Yup. I was hoping to find someone old enough to remember setting these
things up for regular use. I dragged this one out and started cleaning it
up because the 160 MHz auxiliary channels are totally unused in our area,
and the 950 Mhz stuff is very crowded. And you know, this thing doesn't
sound bad. Down 3dB at 8 Khz which may be a transformer issue.

We're using the 160MHz channels in our area as well, since everyone else
went to 450MHz. But I've only had to deal with RPU gear in the past ten
years, so I missed the joys of Marti tube gear. FWIW, the very first
piece of auxiliary broadcast gear I ever laid hands on nearly forty
years ago was a Moseley PCL-303. It was solid state, of course, and back
then transistors that could operate at 950MHz were still considered
magic.

--
John Higdon
+1 408 ANdrews 6-4400
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