[Icom] RE: KK7TV 781 Mods (Bruce Marton)

Sat, 15 Mar 2003 15:48:58 -0800

Hi Bruce,

The Acom 2000A uses two Svetlana 4CX800A's in a grid-driven
(grounded-cathode) configuration with a 50-ohm swamping resistor in the grid
circuit. The swamping resistor will absorb the initial power spike from the
IC-781, and the tubes' grid dissipation will not exceed the maximum rating
(2W per tube).

A problem can arise when the IC-781 drives a grounded-grid 3CX800A7
or3CX400A7/8874 amplifier. The 3CX800A7 has 4W max. grid dissipation, and
the 3CX400A7 has 5W. The spike can cause grid over-dissipation and damage in
these tubes.

Cheers for now, 73,
Adam VA7OJ/AB4OJ

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Bruce Marton
Sent: Saturday, March 15, 2003 11:48
To: [email protected]
Subject: RE: [Icom] RE: KK7TV 781 Mods (Bruce Marton)

The amp is an Acom 2000A.  Krassy has been using his with the 781 for
several years and has not had a failure.  Since he is the US rep for the
company and has a lot of personal experience, I have to take his word
for it.
Bruce

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: Saturday, March 15, 2003 10:55 AM
To: [email protected]
Subject: Re: [Icom] RE: KK7TV 781 Mods (Bruce Marton)

In a message dated 3/15/2003 9:36:32 AM Central Standard Time,
[email protected] writes:

> I do run it barefoot 90% of the
> time, the other 10% is with an amp that is said to be un-affected by
the
> spike, at least the manufacturer claims so.  Therefore, if I have any
> troubles down the road, you know who will be getting a phone call.
>

Which amp manufacturer?

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Your Moderator: Dick Flanagan W6OLD, [email protected]
Icom Users Net: Sundays, 1700Z, 14.315 MHz
Icom FAQ: http://www.qsl.net/icom/