Yaesu FRG-7700 receives AM, not SW

[saki]

I have a Yaesu FRG-7700 shortwave receiver, bought new in 1981, with a
problem. I haven't used it in about a year. It's been stored on a shelf
indoors.

Turning it on again I find that alignment is fine, digital readout is
fine, AM reception is fine but the radio won't hear anything above 1650
MHz except white noise. Antenna length affects volume of white noise but
there are no discernible signals, nothing that causes the s-meter to move.

I've checked the attenuator in the back (DX/Local), which works normally
in the AM frequency range. The front panel ATT, gain and mode are all
working well. I just can't get shortwave out of it. My Icom R75 and
Drake SW4-A hear signals on the same antenna used by the FRG-7700.

Is there something I should be focusing on to troubleshoot, or is this
something I should have a Yaesu/ham gear repair person examine?

Any help would be much appreciated.

----
***@ucla.edu

[Jon Doe]

Post by saki
I have a Yaesu FRG-7700 shortwave receiver, bought new in 1981, with a
problem. I haven't used it in about a year. It's been stored on a shelf
indoors.
Turning it on again I find that alignment is fine, digital readout is
fine, AM reception is fine but the radio won't hear anything above 1650
MHz except white noise. Antenna length affects volume of white noise but
there are no discernible signals, nothing that causes the s-meter to move.
I've checked the attenuator in the back (DX/Local), which works normally
in the AM frequency range. The front panel ATT, gain and mode are all
working well. I just can't get shortwave out of it. My Icom R75 and
Drake SW4-A hear signals on the same antenna used by the FRG-7700.

Try using some spray tuner cleaner on the backside of the
bandswitch.. Looks like it may not be functioning.

[saki]

Post by Jon Doe
Try using some spray tuner cleaner on the backside of the
bandswitch.. Looks like it may not be functioning.

I'll do that, though it appears that the bandswitch is working okay. At
least when I change bands the frequency readout changes too and I hear
different levels of white noise.

Thanks for the suggestion!

----
***@ucla.edu

[Pete KE9OA]

It sounds like either your synthesizer is out of lock or the bandswitching
diodes in the front end aren't being switched by the microcontroller. You
probably have some sort of current booster chip such as a ULNXXXX or some
switching transistors that switch the receiver above the 1.6MHz range. Since
you are hearing different levels of white noise, I believe that your
synthesizer is ok. You can determine that by connecting a frequency counter
to your 1st LO injection point. If everything in this section of the circuit
is ok, you will see a frequency that is above your actual displayed
frequency by whatever the 1st intermediate frequency is. The key is that
when you change your tuning frequency by 1MHz for instance, your 1st LO
frequency will change by that amount.
I don't know if that receiver uses relay or diode switching to switch
different ranges of the preselector when you tune the shortwave bands. You
could actually bypass the preselector and connect an antenna wire directly
to the low-pass filter that is ahead of your 1st mixer. On a final
note.............................is there a switch on the back panel of the
7700 that selects between long wire and 50 Ohm inputs? If so, that could be
the cause. Either that switch is set to the wrong position or it is dirty.
Good luck!

Pete

Post by saki

Post by Jon Doe
Try using some spray tuner cleaner on the backside of the
bandswitch.. Looks like it may not be functioning.

I'll do that, though it appears that the bandswitch is working okay. At
least when I change bands the frequency readout changes too and I hear
different levels of white noise.
Thanks for the suggestion!
----

[Pete KE9OA]

I just downloaded the service manual from mods.dk. Your receiver does use
switching diodes for the preselector, along with an MC14555 chip that drives
them. The 50 Ohm input has a 4700pF coupling cap. The long wire input had a
different path.
If you have a high speed internet connection you can register at www.mods.dk
and download the manual. This will give you a good starting point.

Pete

Post by saki

Post by Jon Doe
Try using some spray tuner cleaner on the backside of the
bandswitch.. Looks like it may not be functioning.

I'll do that, though it appears that the bandswitch is working okay. At
least when I change bands the frequency readout changes too and I hear
different levels of white noise.
Thanks for the suggestion!
----

[Pete KE9OA]

Forget what I said in the last post..............I was looking at another
schematic. The 7700 schematic itself it blurry, but you will need to take a
look at that to get an idea of what is going on.

Post by saki

Post by Jon Doe
Try using some spray tuner cleaner on the backside of the
bandswitch.. Looks like it may not be functioning.

I'll do that, though it appears that the bandswitch is working okay. At
least when I change bands the frequency readout changes too and I hear
different levels of white noise.
Thanks for the suggestion!
----

[saki]

Post by Pete KE9OA
Forget what I said in the last post..............I was looking at another
schematic. The 7700 schematic itself it blurry, but you will need to take a
look at that to get an idea of what is going on.

Thanks for all the detailed information, I appreciate it. I have the
original manual so will look it over to see what I can figure out.

----
***@ucla.edu

[RHF]

Post by saki
I have a Yaesu FRG-7700 shortwave receiver, bought new in 1981, with a
problem. I haven't used it in about a year. It's been stored on a shelf
indoors.
Turning it on again I find that alignment is fine, digital readout is
fine, AM reception is fine but the radio won't hear anything above 1650
MHz except white noise. Antenna length affects volume of white noise but
there are no discernible signals, nothing that causes the s-meter to move.
I've checked the attenuator in the back (DX/Local), which works normally
in the AM frequency range. The front panel ATT, gain and mode are all
working well. I just can't get shortwave out of it. My Icom R75 and
Drake SW4-A hear signals on the same antenna used by the FRG-7700.
Is there something I should be focusing on to troubleshoot, or is this
something I should have a Yaesu/ham gear repair person examine?
Any help would be much appreciated.
----

SAKI,

Yaesu FRG-7700 Information WebPage
http://www.crocuta.com/FRG7700/index.html
http://wiki.radioreference.com/index.php/Yaesu_FRG-7700

The "Yaesu FRG-7700 Shortwave Receiver - Survival Guide
http://foxtango.org/frg7700/FRoG-7700.htm
Fox Tango International -by- Wim Penders [PA0PGA]

Modern Shortwave Receiver Survey @ DXing.Com
http://www.dxing.com/rx/frg7000.htm
Yaesu FRG-7000 General Coverage Communications Receiver

"Recently Sold" Radio Equipment @ Universal-Radio.Com
http://www.universal-radio.com/CATALOG/commrxvr/frg7700.html
Yaesu FRG-7700 Shortwave Receiver
http://www.universal-radio.com/used/sold099.html
Notes: The Yaesu FRG-7700 covers 150 kHz to 29.9 MHz which is tunable
in 1 MHz bands. This multi-mode radio has a digital and analog
display. It also has a built in 12 hour clock-timer and S-Meter. There
is a carry handle on the right side. This radio has the optional
MU7700 memory unit installed which can be fine tuned.
* The Rear Panel has Dual Antenna Inputs
Loading Image...
Loading Image...
and timer relay contacts.

The Yaesu FRG-7700 Receiver Users Group @ Yahoo!
http://groups.yahoo.com/group/FRG-7700/

hope this helps - iane ~ RHF
.
.
. .

[saki]

Post by RHF
Yaesu FRG-7700 Information WebPage
http://www.crocuta.com/FRG7700/index.html
http://wiki.radioreference.com/index.php/Yaesu_FRG-7700....

Thanks, RHF, for the links. I've checked out the Fox Tango info and I'm
a member of the Yahoo user's group, but I'll be glad to look into the
others.

----
***@ucla.edu

[labtech1]

Clean ALL your switches, and pots, mode, band, squelch, etc
I have one of these and that seems to be a common problem
corrosion on the controls ( or dirt, smoke, etc ) My Mode switch
still requires a couple clicks in both directions to work right, probably
from wear.

Post by saki
I have a Yaesu FRG-7700 shortwave receiver, bought new in 1981, with a
problem. I haven't used it in about a year. It's been stored on a shelf
indoors.
Turning it on again I find that alignment is fine, digital readout is
fine, AM reception is fine but the radio won't hear anything above 1650
MHz except white noise. Antenna length affects volume of white noise but
there are no discernible signals, nothing that causes the s-meter to move.
I've checked the attenuator in the back (DX/Local), which works normally
in the AM frequency range. The front panel ATT, gain and mode are all
working well. I just can't get shortwave out of it. My Icom R75 and
Drake SW4-A hear signals on the same antenna used by the FRG-7700.
Is there something I should be focusing on to troubleshoot, or is this
something I should have a Yaesu/ham gear repair person examine?
Any help would be much appreciated.
----

[saki]

Post by labtech1
Clean ALL your switches, and pots, mode, band, squelch, etc
I have one of these and that seems to be a common problem
corrosion on the controls ( or dirt, smoke, etc ) My Mode switch
still requires a couple clicks in both directions to work right,
probably from wear.

Good advice. I've cleaned some but not all. Certainly won't hurt, in any
case, even if the switch appears to be working. Thanks!

----
***@ucla.edu

[RHF]

Post by saki

Post by labtech1
Clean ALL your switches, and pots, mode, band, squelch, etc
I have one of these and that seems to be a common problem
corrosion on the controls ( or dirt, smoke, etc ) My Mode switch
still requires a couple clicks in both directions to work right,
probably from wear.

Good advice. I've cleaned some but not all. Certainly won't hurt, in any
case, even if the switch appears to be working. Thanks!
----

SAKI,

Caution - Keep the Contact Cleaner "OFF" the Face Plate
of the Receiver - Sometimes Sh*t Happens to the Markings
when the Liquid {Solvent} gets on them.

~ RHF
.
.
. .

[saki]

Post by RHF
Caution - Keep the Contact Cleaner "OFF" the Face Plate
of the Receiver - Sometimes Sh*t Happens to the Markings
when the Liquid {Solvent} gets on them.

Thanks for the warning! I'll be careful with the spray cleaner.

----
***@ucla.edu

[Pete KE9OA]

Brenda Ann e-mailed me about here 7700 having a similar problem.
Unfortunately, I accidently deleted her e-mail message. If you are out
there, feel free to shout me down!

Pete

Post by saki

Post by RHF
Caution - Keep the Contact Cleaner "OFF" the Face Plate
of the Receiver - Sometimes Sh*t Happens to the Markings
when the Liquid {Solvent} gets on them.

Thanks for the warning! I'll be careful with the spray cleaner.
----

[Brenda Ann]

Post by Pete KE9OA
Brenda Ann e-mailed me about here 7700 having a similar problem.
Unfortunately, I accidently deleted her e-mail message. If you are out
there, feel free to shout me down!
Pete

Re-mailed you the request.

[Brenda Ann]

Pete,

I got the following bounce message from your ISP (or your mail check
software, more likely)..

Hi. This is the qmail-send program at yahoo.com.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<***@worldnet.att.net>:
204.127.134.23 does not like recipient.
Remote host said: 551 not our customer
Giving up on 204.127.134.23.

Soo.... here's the message, please get back to me at this address or my
other one..

Pete,

I have the same radio and it has an annoying crackle/hiss (when the crackle
becomes constant). This is on all bands. Sometimes it decides to work, and
when it does it's very nice indeed. I'm pulling my hair out trying to track
down the problem. I'm thinking probably in the preselector, since if I
disconnect the preselector output, the noise stops.. on the other hand, so
does all reception (tried connecting a wire antenna through a cap to the
input point, haven't had a working signal generator till just a couple days
ago).

Any suggestions? I could probably e-mail you scans of the schematic if that
would help. I'm almost at my wit's end on this one (it was a Radio-Mart
special.. I should have known better).

Thanks for your time.

Take care, and stay well.

Brenda Ann
--
Say no to institutionalized interference.
Just say NO to HD/IBOC!

Post by Brenda Ann

Post by Pete KE9OA
Brenda Ann e-mailed me about here 7700 having a similar problem.
Unfortunately, I accidently deleted her e-mail message. If you are out
there, feel free to shout me down!
Pete

Re-mailed you the request.