[1000mp] MPV Driving Amp

[J. C. Mc Laughlin]

Dear Group:

    My colleague K8GG has pointed out that my comment was much too simple
and applied to the Alpha 99.  Here is his correction:

The Alpha 91B and 99 use a 50 ohm resistor in the grid input circuit;
The 76 & 78 use swamping resistors across the cathodes of the 3CX400's along
with an UnUn to keep the input close to 50 ohms.
The 77D uses a tuned input tank circuit with the single 8877 and the 77S
uses the tuned input circuit with a 2.25:1 UnUn to get the input impedance
close to 50 ohms with a pair of 8877's.

    Thanks George.  73  Mac  N8TT

J.  Mc Laughlin;   Michigan  U.S.A.
Home:  JCM at Power-Net.Net
----- Original Message -----
From: "J. C. Mc Laughlin" <jcm at power-net.net>
To: <farson at shaw.ca>; "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
Sent: Monday, October 23, 2006 6:54 PM
Subject: Re: [1000mp] MPV Driving Amp


> Dear Group:   It is also true that the impedance of the input of an Alpha
> amplifier is about 50 ohms.  The signal that goes into the amplifier goes
to
> a resistor.  Still, one needs less than 100 w to drive the amplifier to
full
> output.
>
>     73    Mac   N8TT
> J.  Mc Laughlin;   Michigan  U.S.A.
> Home:  JCM at Power-Net.Net