[TenTec] Herc II vs Astron - the final answer

[Tom Macon]

It seems that the problem was caused by the overvoltage protection circuitry in the power supplies being triggered erroneously.  Upon Astron's recommendation, I added a cap to the crowbar circuit on each power supply and the Herc is now hitting on all four cylinders.  I can provide more detail to anyone interested.

 - Tom, K9BTQ

p.s.  - Y'all come to the  Wisconsin QSO Party on Sunday!

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----- Original Message ----- 
From: Tom Macon 
To: Ten-tec Forum 
Sent: Sunday, March 03, 2013 11:19 AM
Subject: 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