[Amps] Re Alpha 9500 Idling Current

[Fern Rivard]

Thanks for all the replies re the idling current on your alpha 9500 amplifier.
I’ve been in touch with Glenn AE0Q at Alpha RF Systems LLC, and here is his quote:
“The Ig zero and tube bias idle Ip (130 ma) must be adjusted via a terminal program with a PC connected to the amp USB or serial port. We don’t have complete written instructions for a customer to do it at this time, there are very dangerous commands that can accidentally be typed while doing that”.
It would probably help getting the detailed instructions if a lot of the owners of the 9500 would request it.
I’m surprised that there isn’t a thing mentioned in the owners manual about any of this especially what the specified idle current should be.
Mine idles at around 30 ma when keyed up but it still puts out an easy 1500 watts but suspect that it has to be driven a bit harder to overcome the higher bias voltage. I’ve had no reports of any distortion either.
Any comments from any of your experts would be greatly appreciated.
Also does the 9500 use EBS or not?
73 from Fern  VE7GZ


-----Original Message----- 
From: Paul Christensen 
Sent: Thursday, December 29, 2016 11:35 AM 
To: 'Amps group' 
Subject: Re: [Amps] Alpha 9500 Idling Current 

> "Paul, My Alpha 9500 runs 232 ma idling current with 3535 volts on the
plate no load and 3420 volts on the plate when idling.  Larry, WA9MAG:

That amount of Ip idle current seems high to me for the 9500.  Possibly
W6WRT and W8ZR can weigh-in with their findings.  Possibly, it was set
higher in software?  

The Alpha 8406 I use on 6m idles at 200+ mA, but I deliberately set it high
in software to help offset an internal EBS timing error.   Hard to believe,
but the 8406 was truncating CW characters in QSK mode.  It was so bad, I
first suspected a fault with the RF input sensor but it's sensing fine.
When observing a QSK-keyed CW waveform on a scope, the 9500 suffers from the
same EBS issue, albeit it's much more subtle and as is typically the case
with EBS, it only affects the very onset of the waveform.           

Paul, W9AC

-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Larry P.
Greenberg
Sent: Thursday, December 29, 2016 12:25 PM
To: amps at contesting.com
Subject: [Amps] Alpha 9500 Idling Current

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