[JMS] Is anyone running a 90881 amp?

Sat, 6 Mar 2004 10:27:50 -0700

Cal,

I'm not experienced with Cathode Modulation, but from what I read in the =
ARRL and Editors and Engineers Handbooks it should not take more drive =
than normal, Class-C operation.  If it would help I could copy some of =
the info in those two books and send it to you in the mail.

Jim
  ----- Original Message -----=20
  From: [email protected]<mailto:[email protected]>=20
  To: =
[email protected]<mailto:james_millen_society@mailman.=
qth.net>=20
  Cc: =
[email protected]<mailto:james_millen_society@mailman.=
qth.net> ; =
[email protected]<mailto:james_millen_society@mailman.=
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  Sent: Friday, March 05, 2004 7:59 PM
  Subject: Re: [JMS] Is anyone running a 90881 amp?

  Thanks Jim/co on the advise:

  FYI, I am not running the 90881 in plate modulation configuration. It =
will be per the manual: that is cathode modulation. I suspect I can jack =
up the bias on this for class C operation. Won't this require more drive =
from the 90800 transmitter? Also, how will this situation be affected by =
cathode modulation? Thanks. Cal, N6KYR.=20

  Cal,

  You can run a push-pull amp in Class C just as well and as easily as =
you can run=20
  it in Class B or Class A.  Just set the bias and plate voltage =
according to the=20
  handbook recommendations.  By the way, we had a home brew push-pull =
812 final on=20
  the air at W8GYH, my High School radio club, back in the 50's.  We =
drove it with=20
  a 90800, ran it class C, and modulated it with a pair of 211's =
(push-pull, class=20
  B).  So I do have some experience with an amplifier that was awfully =
close to=20
  your 90881. =20

  Jim, W8KGI

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