That 2m amplifier is not run zero bias but with normal screen and grid voltages
for AB1.
Power gain is about 13db.
I know the builder quit well.
You see more photos on his web site:
http://www.dj5dm.de/DJ5DM%20R17%20QRP%20Tube/index.htm
73
Peter
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Fuqua, Bill L
Sent: Dienstag, 18. März 2014 06:58
To: Hsu; amps@contesting.com; ham_amplifiers@yahoogroups.com
Subject: Re: [Amps] 4CX5000A in grounded-grid
This type of tube usually doesn't do well in zero bias grounded grid.
Usually the control grid is fried due to excessive control grid current.
But if he is only turning out 1kW then the drive must be low. Also, his
plate voltage for this tube is low compared to normal operation.
The high Q tank, 130kHz bandwidth, must be unloaded during test. That
is a Q of 100. The plate resistance will drop that.
I have 2 old MRI 200MHz 4CX5000a amplifiers in the garage.
Could not resist them at a UK auction.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Hsu [hsu4qro@gmail.com]
Sent: Tuesday, March 18, 2014 1:32 AM
To: amps@contesting.com; ham_amplifiers@yahoogroups.com
Subject: [Amps] 4CX5000A in grounded-grid
Found a interesting web about 4CX5000A(8170) 2m VHF GG power amplifier,
http://www.g4ftc.co.uk/amplifiers/8170_2m/home.htm Anyone use this
configurtion in HF ?how many power gain？
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