[Amps] Alpha 86

[gudguyham at aol.com]

I’ve got an 86 in for repair now and it had loads of problems wit pin diodes in the past. Finally someone put in the Alpha vacuum relay board that was made to do away with the pin diodes.


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On Tuesday, November 8, 2022, 4:52 PM, Paul Christensen <w9ac at arrl.net> wrote:

ETO's documentation of the Alpha 86 is sketchy at best.  The amp went through several re-designs during its production lifecycle, most changes of which are related to QSK performance and PIN diode protection.  The last design iteration added new circuit boards directly behind the front panel.  

>From what I can determine, the 86 laid the groundwork for its successor, the model 89.  Only a couple hundred 86 models were produced by ETO before changing to the more robust model 89 design.  I own an early 86 with no design updates.

Paul, W9AC  

-----Original Message-----
From: Amps <amps-bounces at contesting.com> On Behalf Of gudguyham--- via Amps
Sent: Tuesday, November 8, 2022 4:31 PM
To: David Tenenbaum <dmt013 at gmail.com>
Cc: amps at contesting.com
Subject: Re: [Amps] Alpha 86

It’s odd that it works on 120 and not 240.  I looked in the manual but the terminal strip is not numbered on the schematic.


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On Tuesday, November 8, 2022, 3:24 PM, David Tenenbaum <dmt013 at gmail.com> wrote:

Thanks for the feedback!
I am still on the clock at work but took a break to check R8 and I am seeing 3.98K ohms, so the 4k resistor seems intact. Later tonight when finally done with work I will tear into it to look at the fuses and other resistors, confirm there is REALLY 220 v getting to the unit, and anything else that comes up.
Thanks all for the ideas!!!!
David N1RO/VE3TMK


On Nov 8, 2022, at 2:33 PM, gudguyham at aol.com wrote:
Did you check R8 for open?


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On Tuesday, November 8, 2022, 2:20 PM, David Tenenbaum <dmt013 at gmail.com> wrote:

Hi All,

I have an Alpha 86 that I have been using set up for 110v, and finally have access to 220v, so looking forward to seeing what it can REALLY put out. Unfortunately I have made the jumper changes (terminal in the back for 110 operation has locations 1&2 jumpered, 3&4 jumpered, and 5&6 jumpered, but for 220 only locations 2&3 are jumpered), and the unit fails to light up or come online. I hear a single relay activation when I hit the "On" switch, but no lights or fan.

Fearing I hurt the unit I restored it to 110v operation and all is good. I set it back to 220v and same problem. I checked continuity from the plug's ground to chassis ground, and the hot leads show continuity to the right places. I have been using a 220v SB200 on that outlet just fine.

Any thoughts or leads appreciated! Never thought I would have a problem just switching supply voltages.....Scan of schematic attached....

Best,

David
N1RO/VE3TMK 
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