Yaesu FRG-7700 Survival Manual page 4

Manuals:
Copies of the User Manual and the Service Manual can be obtained from the Fox-Tango website, by far the best website
for all classic Yaesu equipment. If you want to work on your FRG-7700, it is a must to have the manuals and schematics.
See: http://www.foxtango.org
The manuals are very informative and deal with the use and alignment of the receiver, and have a complete partlist.
Another very good source for free manuals is http://www.mods.dk who has manuals of almost all modern Ham
equipment. The only drawback is that you are limited to 2 manuals a day. On this site are also modifications, pictures,
descriptions and more. Recommended!
Parts:
Unfortunately after 20+ years there is no dealer around who still carries spare parts, but fortunately there are not much
special parts used in this receiver and most parts are easy substituted by standard parts.
The receiver is very rugged and, normal used, there are not much problems.
The only parts that can give trouble after longer use are the mechanical parts as switches and potmeters. It is not easy to
find replacements for them, keep an eye open for special parts at hamfests, or have a good junkbox with old radio parts.
I can recommend the Graveyard section on the Fox-Tango site, they are a excellent source for special parts. See for
yourself at www.Foxtango.org
Alignment:
Most FRG-7700 receivers have no problems, but after 20+ years of use, a re-alignment can be necessary.
To align the receiver, you have to be very familiar with the used circuits or you end up with a worthless piece of junk, if
you don't understand what you doing. That is true for all kinds of communication equipment. I have seen all kinds of
junky stuff on e-bay, that was tampered with and sold for high prices,to the chagrin of the new owner.
Most of the time the problem is a loss of the frequency coverage, usually at the end of the tuning scala.
The receiver has normally a overlap at each range from between 30 to 50 khz at each side from the range, for example at
7 Mhz the receiver tunes from 6950 to 8050 khz, and other bands have the same overlap at each end.
The PLL circuit in the FRG-7700 needs some attention if you have the following sympthoms:
If the end point of each Mhz range is getting lower at the high side of each band, a re-alignment of the first PLL is
necessary, ( receiver receives not higher than 950 or so on the analog scala )
If only the end points at the 5, 12, 20 and 29 Mhz bands are too low, a re-alignment of the second PLL is necessary.
This alignments are not difficult to do, you need a good counter, a VTVM, RF millivolt meter or oscilloscope and fitting
plastic or ceramic tuning tools. Under no circumstances use metal screwdrivers for alignment of the coil cores, they will
ruin the cores. Use only fitting plastic or ceramic alignment sets.
For the trimmers use a small screwdriver or a ceramic one,
The procedure to align the PLL is described in the Yaesu Operator and also in the Service Manual,
There are some changes to make in the manual:
PLL Reference oscillator Adjustment:
Set the MR switch off, and connect a frequency counter to TP04, (instead of pin 9 of the MB-84040B ic, as the manual
says) and adjust TC 2002 for a frequency of exact 6.400 Mhz on the counter.
The result is the same as in the manual, but you don't have to work at the ic, with the risk of shorting pins.
The PLL Local alignment can be done as in the book, if you don't have a HF VTVM to measure the voltage, you can use a
HF oscilloscope for this alignment, together with a counter.
However, if you do'nt have either, skip this alignment, If you receive signals, this section is working. Just check for a 47.6
Mhz signal.
For alignment of the first PLL, connect your dc VTVM to TP05 in front of the first PLL box, and rotate the main dial to the
"1000" position of the analog dial. Adjust T2007 for a reading of 7 volts on the meter. Try to make 7 volts as close as
possible.
PAØPGA
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