Carl,
Thanks for the advice. I'll keep focused on drive and grid current. On most
bands,I'm getting 800-900 watts out which is probably the best that can be
expected from old tubes.
73,
Jeff
-----Original Message-----
From: Carl <km1h@jeremy.qozzy.com>
To: tz4am <tz4am@aol.com>; amps <amps@contesting.com>; wa6fgi
<wa6fgi@steeltrails.net>
Sent: Thu, Jan 3, 2019 1:58 am
Subject: Re: [Amps] Alpha 76A drive levels...
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
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
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