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Yaesu frg 7700


#1  27/06-20 17:12
Steen Willumsen
Indlæg: 38
Hej.
Mon der er nogen der ved hvor fejlen ligger, når vfo'en
Ikke fungerer på en modtager yaesu FRG-7700?
Og jeg vil også gerne prøve at resette stationen, hvirdan?
På forhånd tak
Mvh Steen
OZ1IBK

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OZ1IBK

#2  28/06-20 00:03
Steen Jensen

Indlæg: 532
Svar til #1:

http://foxtango.org/frg7700/FRoG-7700.htm


It's possible that there's something wrong with one of the
circuits to which a variable-capacitor section is connected. For
example, the VFO might be stopping entirely when you try to tune it
into part of its range. This might indicate (e.g.) a weak transistor,
or a capacitor that has become leaky... something which causes the
gain inside the oscillator loop to drop below 1.

Best way to distinguish would probably be to hook a frequency counter
and/or o'scope to the output of the VFO unit. Tune it through its
range, and see if you get a reasonable output signal throughput the
range.

If the VFO produces a consistent signal, then the next suspect would
be the PLL board, which generates the IF frequencies by multiplying
the output of the VFO. The PLL might be losing lock for some reason,
and shutting down. If the VFO works OK, then scope/count the IF
outputs from the PLL, and see if they vanish suddenly or get "stuck"
somehow.

The manual has the alignment procedures.

You should also do an "eyeball" inspection to look for obvious
failures, such as bulging or leaking electrolytic capacitors. These
units are old enough that it might have been built with some 'lytics
that suffer from the faulty-electrolyte "capacitor plague". If so, a
careful re-capping (with repair of any damaged traces on the board)
would be called for.

Redigeret 28/06-20 00:11
#3  28/06-20 10:01
Steen Willumsen
Indlæg: 38
Svar til #2:
Tak for svar.
Jeg tror den må en tur op til Peter Opfinder,
Men igen, tak for svar.
Mvh Steen
OZ1IBK

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OZ1IBK

#4  28/06-20 13:57
Peter Andersen (peel.dk)
Indlæg: 417
Svar til #3:

Bor du nærheden af Stenløse er du også velkommen til at smide dem forbi mig, så skal jeg se på den hvis det ikke er noget der haster til i går.

Peter

#5  28/06-20 14:13
Steen Willumsen
Indlæg: 38
Svar til #4:
Gider du lige ringe mig på 50311170?
Mvh Steen

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OZ1IBK