Lots of the ordinary things have been checked, but-
Have you checked the Bird?
Bill-W4BSG
At 07:38 PM 5/29/01 -0700, you wrote:
>-
>Hello there,
>-
>A non amps member, Bob W0YVA Emails me with
>a problem he's having with his just purchased used
>Alpha A77. Care to take a stab with your opinion of
>the problem..?
>-
>I have directed him to watch the amps archive for
>your answers. Below is a copy of his text to me...
>73's-skipp
>-
>[snip]
>: Here is what I have:
>:?This is a "new" A77 (looks like never used) -
>: Serial 2556.
>: Seems to be okay except very low power output
>: (200 watts or so) with 80 watts drive. There is
>: plenty of grid current. Applying drive results in
>: significant plate current (800ma or so) which
>: can be dipped (the dip is very shallow) for
>: "max" power. HV reads normal. Power is
>: being measured with Bird wattmeter using
>: 5KW Bird dummy load. Problem appears on all
>: band segments.
>-
>: Here is what I have done:
>-?
>: 1. Replaced 8877 with known good tube - no
>: difference.
>: 2. Checked bias directly at 8877 socket -
>: switches properly from high to low with
>: drive applied.
>: 3. The zener, D13, seems okay - checked
>: with ohmmeter.
>-
>: Where is the power going with all that plate
>: current? Weird.
>-
>: Suggestions for what to check? The plate
>: tank components all look good - no evidence
>: of heat anywhere.
>-
>: Any help would be appreciated.
>- ?
>: 73, Bob
>: W0YVA
>
>________________________________________________________________
>GET INTERNET ACCESS FROM JUNO!
>Juno offers FREE or PREMIUM Internet access for less!
>Join Juno today! For your FREE software, visit:
>http://dl.www.juno.com/get/tagj.
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
>
-
Bill Aycock --- Persimmon Hill
Woodville, Alabama, US 35776
(in the N.E. corner of the State)
W4BSG -- Grid EM64vr
baycock@HiWAAY.net
w4bsg@arrl.net
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|