[VHFcontesting] Nuking

[kb7dqh at donobi.net]

Hmmm.. Did you a favor I would guess.  The JFET preamps in the "brownface"
Mirage bricks were not all that splendid... Most did a really good job of
masking the antenna/RF background noise with its own and served more as an
"s-meter-pusher" than anything else.

  Only radio that seemed to benefit from
the use of the preamp in my B1016 was my first FT 726R, which, has the
best sensitivity of any of my two meter radios, with the exception of my
Kenwood
TM255A...  My only guess is the Yaesu has a proper "noise-matched"
impedance match between its receiver frontend and the preamp's output.

I also purchased one of the "mfj" Mirage B1016G  amps, used, shot too much
power thru it when initially testing it by mistake, and blew out the
driver transistor... no surprise there, I guess, but I have had other amps
which sustained similar damage and have survived largely unscathed. 
Rather than junking the brick, I removed the offending driver transistor,
(which after the cooking made a wonderful oscillator:-) jumped the traces,
cleaned the biasing components from the RF circuit, and proceeded to
retune the input network by a bit of discrete component "snowflaking"
which fought the input VSWR down to nearly unity, and brought the amp up
to full output, with 30W
of drive.  The High output VSWR protection circuit never really worked,
the SSB relay delay circuit is toast, but, hard-keying the amp makes it
useable!

So, until I get the Quintron  VHF solid-state 300W (Class B) paging amp
retuned, I will use the Mirage...

Eric
KB7DQH

> I have had a couple of the "original" Mirage amps that have served me
> well.
>
> In my current one, the pre-amp mysteriously self destructed, but it
> doesn't really bother me so I haven't bothered to fix it.
>
> 73
> Dan
> --
> K9ZF /R no budget Rover ***QRP-l #1269
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>
>
>
> Dexter McIntyre W4DEX wrote:
>> I have three Mirage amps that have been well used an abused for many
>> years.  The only trouble I've had and still have is a bad contact on the
>> T/R relay.  The contact will occasionally be open on the receive path
>> after a transmission.  The amp was once used for a packet node so I sure
>> can't complain about it having a worn out relay.  All of these amps are
>> probably 20 years old so maybe newer ones aren't the same design.
>>
>> Dex
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