[amsat-bb] Re: Devices in Icom preamps AG-25 AG-35

Mark L. Hammond marklhammond at gmail.com
Thu Mar 18 03:44:13 PDT 2010

Hi George,

Thanks for the tips. We had a measured 12V at the connector attaching
to the preamps and the menus were correct, so every thing indicates
something was amiss on the preamp-hardware side.

I hope my colleague can get his preamps in working order.

Does anybody have the device information for the AG-25 units?


Mark N8MH

On Thu, Mar 18, 2010 at 12:20 AM, George Henry <ka3hsw at att.net> wrote:
> I should have offered this first:  before suspecting the preamps, did you
> enable preamp control for each band in the 910's "SET" menu?  Preamp control
> must be enabled before the front panel P.AMP button will switch power to the
> preamp.  Also, there must not be anything inline such as an SWR meter,
> filter, or anything else that might block DC on the coax.
> If you hook the preamp up to the rig with a short jumper cable, you should
> head a noticeable relay click from the preamp when you press & hold the
> P.AMP button.
> George, KA3HSW
> ----- Original Message ----- From: "Mark L. Hammond"
> <marklhammond at gmail.com>
> To: <amsat-bb at amsat.org>
> Sent: Wednesday, March 17, 2010 5:29 PM
> Subject: [amsat-bb] Devices in Icom preamps AG-25 AG-35
>> Hello all,
>> We either had two bad preamps to begin with, or they became casualties
>> during transport to K4T, but regardless--the Icom preamps we took appear to
>> have bad GAsFET devices in them.
> [snip]

Mark L. Hammond [N8MH]

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