I dont even look at the plate current other than see its there. With those
drive levels and soft tubes you will never get too much.
Carl
----- Original Message -----
From: tz4am@aol.com
To: km1h@jeremy.qozzy.com ; amps@contesting.com ; wa6fgi@steeltrails.net
Sent: Wednesday, January 02, 2019 1:57 PM
Subject: Re: [Amps] Alpha 76A drive levels...
Carl:
Got it. I keep the grid at 60 ma max.
But on 40m to get 60 ma, I have to drive with 87 watts which seems a bit
much, pushing out 1 KW. On other bands drive is only 40-60 watts but output
is only 800-850 watts with 60 ma of grid current.
For my 3-holer, what should be the max plate current allowable?
73,
Jeff
-----Original Message-----
From: Carl <km1h@jeremy.qozzy.com>
To: tz4am <tz4am@aol.com>; amps <amps@contesting.com>; wa6fgi
<wa6fgi@steeltrails.net>
Sent: Wed, Jan 2, 2019 3:43 pm
Subject: Re: [Amps] Alpha 76A drive levels...
The tubes are rated at up to 30ma each so you can run them all at 60ma as
now until they need replacinrg or a 2 x 3CX800A7 conversion.
I tune using the grid current peak only using the Load control to increase
or decrease the grid current and the Tune control to do the peaking.
Carl
----- Original Message -----
From: tz4am@aol.com
To: km1h@jeremy.qozzy.com ; amps@contesting.com ; wa6fgi@steeltrails.net
Sent: Wednesday, January 02, 2019 4:32 AM
Subject: Re: [Amps] Alpha 76A drive levels...
Carl:
I have a 3-holer, with so-so tubes.
On 40 meters on the SSB setting, tuning to keep grid current maximum at no
higher than 0.6 on the scale and a dip in plate current, I get about 1 KW
forward power; it takes about 87 watts to get this output with so-so tube.
On other bands, the same procedure yields about 850 watts with drive of
between 40 and 60 watts.
Is this the right procedure for tuning or should I be doing things
differently?
73,
Jeff
-----Original Message-----
From: Carl <km1h@jeremy.qozzy.com>
To: tz4am <tz4am@aol.com>; amps <amps@contesting.com>; wa6fgi
<wa6fgi@steeltrails.net>
Sent: Wed, Jan 2, 2019 2:24 am
Subject: Re: [Amps] Alpha 76A drive levels...
As low as required to peak the output at 1200W, about 30-40 ma total with
used tubes at 60W or so.
I bought this amp as a basket case, bad tubes, transformer, bandswitch, etc,
so do not know what it did when new.
Carl
----- Original Message -----
From: tz4am@aol.com
To: km1h@jeremy.qozzy.com ; amps@contesting.com ; wa6fgi@steeltrails.net
Sent: Saturday, December 29, 2018 11:02 AM
Subject: Re: [Amps] Alpha 76A drive levels...
Carl,
Thanks for the information. What is the grid current reading at 1200w?
Jeff
TZ4AM
-----Original Message-----
From: Carl <km1h@jeremy.qozzy.com>
To: amps <amps@contesting.com>; Gary Smith <wa6fgi@steeltrails.net>
Sent: Sat, Dec 29, 2018 2:59 pm
Subject: Re: [Amps] Alpha 76A drive levels...
Alpha offered a low drive mod for that series of amps, check their legacy
amp docs.
My 76PA 3 holer will easily run 1800W with100W drive, I back it down for
1200W.
Carl
----- Original Message -----
From: "Gary Smith" <wa6fgi@steeltrails.net>
To: <amps@contesting.com>
Sent: Sunday, December 23, 2018 5:06 PM
Subject: [Amps] Alpha 76A drive levels...
To the group:
Have a friend who recently purchased a Alpha 76a two-holer.
He currently is driving it about 65 watts getting 500 watts or so output.
As he has no instructions on the amp, is this low level of drive okay or
should it be driven at a higher level of input power.
Thanks to the group,
Gary...wa6fgi
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