On Mar 12, 10:11*pm, Bruce in alaska wrote:
In article
,





*terry wrote:
We have a non working Raytheon GL-9 small boat radar; probably 10 to
20 years old?

Investigations seem to indicate that the receiver section of the
printed circuit board of the mast mounted scanner, transmitter
receiver unit is defective. It appears that there is no *noise reading
at TP5 (test point) on the receiver/modulator PCB CNM179 printed
circuit board. The complete mast unit is numbered # M52559.

Other functions (e.g. the controls of display unit) seem to be OK.

Some of the parts seem to be made by JRC (Japan radio Co.).

We were able to download the user/installation manual but not a
deailed circuit diagram and test readings.

Anybody have any advice about the possibility of having the mast unit
repaired, hopefully *somewhere in eastern Canada.

Any advice appreciated.

Are you sure it is the Receiver/Modulator board, and not the Xband
LNA/DownConverter that feeds it? *The Test Point, you mention above is
the Baseband video Output of the whole Receiver, and only means that the
whole receiver "Could" be dead. When you turn the Gain control Full Up,
and the Sea Clutter Full Off, do you get sparkles on the Display? Are
you reading this with a VOM, or looking at this Test Point with an "O"
Scope?

--
Bruce in alaska
add path after fast to reply- Hide quoted text -

- Show quoted text -

Thanks Bruce for your reply.
Not absolutely su
We connected an oscilloscope to TP5 hoping to see white noise which we
could then adjust to 2 volts p-p. We understand TP5 is after the 60
meg IF strip but before the signal goes into the demod. cct. Not
seeing anything but low level (20 millivolts) general noise did not
adjust anything.
Connecting and disconnecting oscillator/mixer front end of the
receiver (which converts the 9.445 gig echos to approx 60 megahetz),
made no difference. Also trying to feed in a 60 meg signal from a sig.
gen. to the front end of the IF (where that front end of the receiver
plugs in) even at a relatively high level, we get nothing at either
TP5 or the so called video output lead that conveys the IF/Demod
output to the display unit. This with the receiver front end plugged
in and not plugged in.
BTW we don't have any other DC voltage info. on that PCB to check. But
something 'seems' dead in the IF strip??? Or the front end of the
receiver?
Any suggestions most welcome.
Terry and Alfred