[ICOM] Repairing a IC-471H

[wb4mle at surfbest.net]

On Tue, 12 Oct 2004 23:00:02 -0400, you wrote:

>Well my trusty 471H has stopped putting out RF. It appears to put out a 
>VERY small amout, too small for a Bird to register, as I can hear it on 
>a hand held on the output frequency.
>
>There is voltage in all the right places in the PA module except the 
>output volts on IC 1, which seems to be a power module.
>Does anyone know what the input/output power levels of this module is ? 
>I guess it has to be about 10-20watts out to drive the final. Also what 
>is HV and PAV on J1 in the PA. Could a failure in the power control 
>circuit be the cultprit? How can I test it

I believe the manual is wrong on the output voltage of IC1. It is
capacitively isolated inside the module (SC1016). Also pin 2 and 3
voltage readings reversed. 
Try checking output at 449 mhz. If output is up some there, it's
probably one of the (##**$$) cheap plastic trimmers in the pll/rf
chain. Receive sensitivity reduced at the same time as the output low
points to the pll chain trimmers. Mine has the same problem FWIW.
-- 
Eddie Seymour, WB4MLE
E-Mail wb4mle at surfbest.net