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Re: [Amps] Alpha 87A Mic Click Grid Current Spike

To: <amps@contesting.com>
Subject: Re: [Amps] Alpha 87A Mic Click Grid Current Spike
From: "JOS Earthlink" <jsternmd@earthlink.net>
Date: Thu, 8 Nov 2007 19:02:21 -0500
List-post: <mailto:amps@contesting.com>
-----Original Message-----
From: JOS Earthlink [mailto:jsternmd@earthlink.net]
Sent: Thursday, November 08, 2007 7:01 PM
To: Paul Christensen
Subject: RE: [Amps] Alpha 87A Mic Click Grid Current Spike


Hi Paul,

Thanks for the short-cut.  I first checked the output of my ICOM xcvr to
make sure that there wasn't any RF spike with power knob down to zero on a
sensitve powermeter with peak hold and all was fine.  Following your
suggestion, I disconnected the coax and only keyed the amp via the Key input
control to the Alpha (I have no ALC connected between ICOM and Alpha) and
sure enough there was the Grid current spike of 70ma.  I am only worried
because the Grid current redlines at 100ma and it usally runs at only about
20ma with full power...maybe 30ma on the higerh freqs.  Any other ideas are
appreciated.

73 de  K1JOS (Jerry)
CCA #11906
CRA #1777





-----Original Message-----
From: Paul Christensen [mailto:w9ac@arrl.net]
Sent: Thursday, November 08, 2007 6:29 PM
To: JOS Earthlink; Amps Amps
Subject: Re: [Amps] Alpha 87A Mic Click Grid Current Spike


> Just noticed that when I PTT on my mic that my Alpha 87A Grid current
> always
> shows a momentary spike of about 70ma.

Start by taking the transceiver RF out of the equation.  Remove only the
coaxial cable between the 87A and transceiver.and key the amp's PTT line
with the transceiver.  Even better, bypass the transceiver altogether and
key the amp's PTT line with a dry contact closure.  If the grid current no
longer spikes, then the transceiver may be producing a short burst of high
power even with negligible drive.

Paul, W9AC


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