[Amps] Alpha 76A drive levels...

[tz4am at aol.com]

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 at jeremy.qozzy.com>
To: tz4am <tz4am at aol.com>; amps <amps at contesting.com>; wa6fgi <wa6fgi at 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 at aol.com
To: km1h at jeremy.qozzy.com ; amps at contesting.com ; wa6fgi at 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 at jeremy.qozzy.com>
To: tz4am <tz4am at aol.com>; amps <amps at contesting.com>; wa6fgi 
<wa6fgi at 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 at aol.com
To: km1h at jeremy.qozzy.com ; amps at contesting.com ; wa6fgi at 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 at jeremy.qozzy.com>
To: tz4am <tz4am at aol.com>; amps <amps at contesting.com>; wa6fgi 
<wa6fgi at 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 at aol.com

To: km1h at jeremy.qozzy.com ; amps at contesting.com ; wa6fgi at 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 at jeremy.qozzy.com>

To: amps <amps at contesting.com>; Gary Smith <wa6fgi at 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 at steeltrails.net>



To: <amps at 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 at contesting.com



> http://lists.contesting.com/mailman/listinfo/amps











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