[Amps] Alpha 76a

Jeff Blaine keepwalking188 at yahoo.com
Mon Sep 12 20:53:12 PDT 2011


Guys,

There is an error on the W6XX schematic last time I looked.

73, Jeff ACØC
www.ac0c.com

-----Original Message----- 
From: ROBERT HARMON
Sent: Monday, September 12, 2011 3:23 PM
To: amps at contesting.com
Subject: Re: [Amps] Alpha 76a

Pat,
Congratulations on acquiring the 76A, she will serve you well !
The grid overcurrent protection is a good idea.  I am considering this for my amp.  Normally I keep
a close eye on the grid current but in the heat of battle during a contest sometimes we lose our grip, hihi.
One thing you might consider if you haven't already is replacing the power supply HV filter caps.  They are more than ready
to be replaced if they are the originals.

73,
Bob
K6UJ


On Sep 12, 2011, at 12:00 PM, Patrick Barthelow wrote:

>
> I received a  76A about 6 months ago, as a gift from a OOM who I helped a lot when he was active.  A 3 holer, that had been stored 
> for some time, I "gettered" it, slowly, bringing it back to life, without incident.  On ALL amps I have run, I am hyper aware and 
> observant of grid current, in the interest of long life, and note that Bob Wolbert has published a grid overcurrent trip circuit 
> for the Alpha, that might be wise to install.   While getting used to normal tuning dynamics of my New/old stock Alpha, I was 
> startled somewhat at the grid current dynamics.  At how quickly  the Ig goes from very low values to very high values with small 
> adjustments of input power, and tune and load controls, even with a good amount of loading.  Perhaps this is "normal" for a 3 
> holer '76A but maybe it is saying something about one or more tubes.   Other than that Ig sensitivity, the Alpha  is  the "AC 
> Cobra  427 " of amps, IMHO.  and with winter coming up, if I operate QRO with it, I will no
t
> heed a shack heater, or a fire to cook marshmallows.
>
> Best Regards,
> Pat Barthelow  AA6EG
>
>
>
>> Date: Mon, 12 Sep 2011 13:31:22 -0500
>> From: mikea at mikea.ath.cx
>> To: amps at contesting.com
>> Subject: Re: [Amps] Alpha 76a
>>
>> On Mon, Sep 12, 2011 at 11:20:33AM -0700, ROBERT HARMON wrote:
>>> Charles,
>>>
>>>
>>> I agree 100%. The Alpha 76PAC is one of the best amps ever made, a real
>>> workhorse. Like a Timex watch, "takes a licking and keeps on ticking" ,
>>> with one caveat, as you indicated, watch the grid current.
>>> I run mine hard all the time (and keep a watchful eye on the grid
>>> current)
>>> Remember the "brick on the key" advertisements for these amps ? My
>>> favorite is the ad used in 1981 which shows the usual heading of " Key
>>> Down, How Long ?" and instead of the normally used brick on the key there
>>> is a skeleton sitting there with his hand on the key. Now thats a good
>>> amp ! hihihi
>>
>> Erm ... As long as he's not wearing a nametag that reads "Ross Hull".
>>
>> -- 
>> Mike Andrews, W5EGO
>> mikea at mikea.ath.cx
>> Tired old sysadmin
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>
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