[Johnson] Invader Problems

[David C. Hallam]

I am operating in the 200 watt position.  After the wait, I can tune to
normal full output on my Bird 43 wattmeter. High and low voltages are OK.
After hours output drops to 0.  Grid bias is normal and no power output on
any band and no signal in the zero position unless I put a receiver antenna
lead inside the cabinet.  With the any setting of the zero level control and
antenna coax connected as normal, I can not hear a spotting signal.  With a
general coverage receiver, I can hear the 9 MHz carrier oscillator and the 5
MHz vfo and a little output from the 2nd mixer as stated above.

My preliminary diagnosis is that the driver stage is not working.

I have tested and substituted 2nd mixer and driver tubes with no change.

David
KC2JD

> -----Original Message-----
> From: Dennis Petrich [mailto:dpetrich at wavecrest.com]
> Sent: Tuesday, September 19, 2006 10:30 AM
> To: 'dhallam at rapidsys.com'; Johnson List
> Subject: RE: [Johnson] Invader Problems
>
>
> What do you mean by output coming and going?  Please be more
> specific.  What
> is the plate current doing?  What is the High voltage doing?  What is the
> grid drive doing, what is the output power doing? And so on....
>
> Dennis, k0eoo
>
> -----Original Message-----
> From: johnson-bounces at mailman.qth.net
> [mailto:johnson-bounces at mailman.qth.net]On Behalf Of David C. Hallam
> Sent: Tuesday, September 19, 2006 9:25 AM
> To: Johnson List
> Subject: [Johnson] Invader Problems
>
>
> I have just moved my Invader 2000 to the beach to start trouble
> shooting on
> a problem that has me puzzled.
>
> When I turn the rig on, I have to leave it on standby for 20/30 minutes
> before I can get any output.  Then after 2 or 3 hours of operation, the
> output goes away.  If I let it sit overnight, I can get output again after
> the 20/30 minute wait.
>
> What in the world might take than long to "warm up" before it
> works and then
> get "too hot" to operate after a few hours?
>
> David
> KC2JD
>
>
>
>
>
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