[TenTec] Herc II vs Astron

[Bob McGraw - K4TAX]

You will likely need to add blocking diodes in the output line of each 
supply.  Then you will need to raise the voltage of each supply to offset 
the drop of the diodes.  Be sure the leads from each supply, both negative 
and positive are precisely the same length, connected to a common point, 
such that the R value of each lead is exactly equal in terms of R value. 
Each supply will need to be adjusted at rated load to exact voltage thus 
each supply delivers 13.80 volts.  Any unbalance will be seen as burden on 
any other supply.  Thus it may shut down due to the current limit circuit.

I can be done, but must be done very carefully and accurately.

73
Bob, K4TAX






----- Original Message ----- 
From: "Tom Macon" <tmacon at wi.rr.com>
To: "Ten-tec Forum" <tentec at contesting.com>
Sent: Sunday, March 03, 2013 11:19 AM
Subject: [TenTec] Herc II vs Astron


> Hi, all -
>
> I have replaced the four supplies in the 9420 beast with four Astron 
> SS-25's.  At first all seemed well but then I experienced reduced power 
> out from the 420 Herc.
>
> Upon investigation, it seems that one or more of the Astrons shuts down so 
> not all four sections of the amp are powered.  I see that, if I turn off 
> one supply, that there is backfeed from the amp showing up on its output. 
> My guess is that  the one of the supplies (a little slower to come up?) 
> senses the backfeed voltage from another one and this triggers some 
> protection feature.
>
> I have only the sheet that came with the Astrons - no schematic or 
> detailed technical info.  Tomorrow I will call them to see if they can 
> shed any light, meanwhile perhaps someone here has experience or insight?
>
> 73,
> Tom Macon, K9BTQ
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