Icom IC-R7100 receiver/scanner problem

[Ed Majden]

I have an ICOM IC-R7100 receiver/scanner that has a problem. I can
receive nothing below 250 mhz. There is no hiss or noise, just like if the
squelch was fully turned up, and it is not. It works fine from 250 mhz+ to
762 mhz where it sometimes cuts out as described above. Any idea of what is
wrong with it??? Does anyone have a schematic or repair handbook for this
radio? Thanks for the help.
Ed

[mikeFNB]

i would be inclined to do a factory reset first

http://www.maeselectronics.be/index.htm?page=icom/reset.htm

mike

Post by Ed Majden
I have an ICOM IC-R7100 receiver/scanner that has a problem. I can
receive nothing below 250 mhz. There is no hiss or noise, just like if the
squelch was fully turned up, and it is not. It works fine from 250 mhz+ to
762 mhz where it sometimes cuts out as described above. Any idea of what is
wrong with it??? Does anyone have a schematic or repair handbook for this
radio? Thanks for the help.
Ed

[**THE-RFI-EMI-GUY**]

If the reset does'nt work I would suspect the VCO/PLL for the lower
bands is going out of lock. Usually an unlock indication will mute audio.

Post by Ed Majden
I have an ICOM IC-R7100 receiver/scanner that has a problem. I can
receive nothing below 250 mhz. There is no hiss or noise, just like if the
squelch was fully turned up, and it is not. It works fine from 250 mhz+ to
762 mhz where it sometimes cuts out as described above. Any idea of what is
wrong with it??? Does anyone have a schematic or repair handbook for this
radio? Thanks for the help.
Ed

[Pete KE9OA]

R51 on the main board may be out of adjustment. On the bands where the unit
is working, the squelch shouldn't mute the noise until you advance it to the
10:00 position of rotation. If it mutes the receiver at a less advanced
position, R51 may require adjustment.
One way that you can check if the PLL is in lock is to tune the receiver to
a frequency where it "goes dead" and inject a signal of around 100uV with an
RF generator. If you don't have this type of equipment, tune in to a local
weather band frequency and see if you can hear one of these stations.
Another thing you can do is tune in one of the local stations on the 88 to
108MHz FM band. If you don't hear any stations in any of these ranges, your
PLL could indeed be out of lock.

Pete

If the reset does'nt work I would suspect the VCO/PLL for the lower bands
is going out of lock. Usually an unlock indication will mute audio.

Post by Ed Majden
I have an ICOM IC-R7100 receiver/scanner that has a problem. I can
receive nothing below 250 mhz. There is no hiss or noise, just like if the
squelch was fully turned up, and it is not. It works fine from 250 mhz+ to
762 mhz where it sometimes cuts out as described above. Any idea of what is
wrong with it??? Does anyone have a schematic or repair handbook for this
radio? Thanks for the help.
Ed

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."
"Follow The Money" ;-P