[Amps] Alpha 87A Alpha Max Upgrade

[Jarrad Mitchell]

If I may,



I would suggest that it ultimately depends on the effort one wishes to go to.  Whilst you may not be able to 'clone' the chips by doing a firmware dump, I doubt they would be particularly challenging to reverse engineer.



For starters, the architectures of tube PAs are pretty well known - so anyone undertaking the task should have a reasonably easy time figuring out what the inputs and outputs of the chips are.



Likewise, they would also have a fair idea of the intended purpose of the chips, and at least some theories pertaining to how the chips should accomplish their task.  I'd suggest there is a reasonable amount of experience with this given that Alpha is not the only company to offer auto-tune amplifiers.



One would then design a test procedure, and measured the inputs and outputs of the chips whilst running the procedure.



By combining the experimental data with the theory and known purposes of the chips, a competent engineer should then be able to create a replacement part.



They did it with the first IBM PC (only the BIOS chips were IBM propriety), and I am confident it can be done significantly more easily with a tube amplifier.



Whether or not one would bother, I don't know.  It may be prudent instead to design a generic control board for auto-tune tube amplifiers, and then offer conversion boards to those that need them.



That said, how many control boards are failing compared to tubes?  Given the price of 3CX800A7s, I dare say there will not be a shortage of working second hand logic boards from 87As that people just can't afford to re-tube.



Why are we worrying about control logic ICs that rarely fail, when there is a well-known elephant in the room?



Just my thoughts... I know hams are scared of ICs... but me?  I'm scared of tube availability.



Jarrad Mitchell

h: VK3BL & XU7AGA



________________________________
From: Amps <amps-bounces at contesting.com> on behalf of Jerry O. Stern <jsternmd at att.net>
Sent: Sunday, 9 October 2016 2:17 AM
To: 'Paul Christensen'; amps at contesting.com
Subject: Re: [Amps] Alpha 87A Alpha Max Upgrade

I believe the greatest issue with maintaining the 87A further down the road
are the hard programmed PALs (16 and 20) that as I understand cannot be read
or cloned.  Anyone have any success?

73 Jerry
NY2KW



-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Paul
Christensen
Sent: Friday, October 07, 2016 11:58 AM
To: amps at contesting.com
Subject: Re: [Amps] Alpha 87A Alpha Max Upgrade

Jim,

Yes, you can upgrade it without difficulty once you have the
AlphaMax/AlphaRemote chips.  I've upgraded several 87A amps over the years.


Maybe check with Mike Dishop or Glenn Pladsen concerning chip availability.
Come to think of it, it might not be a bad idea for those of us who love the
87A to stock up on those chips as well as RAM/ROM.  Most all other parts
used in the 87A can be sourced from other vendors, including compatible
substitutes.

If you decide to go through with the amp purchase, also consider bumping up
the Rx diode bias voltage by adding to the Zener string.  As I recall,
there's on-line information for the mod and it would bring the amp up to
late-production performance by adding even more SWR protection to the Rx PIN
diodes.  I firmly believe the bad-rap given to the 87A/89 PIN design is
attributed to Rx bias.  If my information is correct, Alpha did not achieve
the last level of bias improvement until about 2000.  That's a full decade
of 87A/89 production that may benefit from a bias circuit upgrade.

Paul, W9AC

-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Tuesday, October 4, 2016 2:08 PM
To: Amps Amps <amps at contesting.com>
Subject: [Amps] Alpha 87A Alpha Max Upgrade

I'm considering the purchase of an 87A that shipped from the factory in
1993. I suspect that it does not have Alpha Max firmware. Some questions.

1) How big a deal is this?

2) I know that chips must be changed and that firmware must be loaded.
Are these generally available?

3) Any known issues with doing it now?

Thanks and 73, Jim K9YC

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