NavList:

In your description of “adjustments in their extremes” I take it you refer to the manual gain, range control adjustments, PRR control, sea clutter control and fine tune adjustment knobs? The problem may be located in the magnetron unit (not good at all) or just be a section of corroded wave guide (again, not good) and not your receiver. Please advise.

 

Robert responds:

 

Yes, correct, but only for sea clutter and tune.

 

Ok. If you have, or can find, the electrical schematics to your unit you may be able to extend the functional life of your unit. There is a modulator circuit, most likely on the mother board, that can be re-adjusted (centered) by turning a trimmer potentiometer in that circuit. But I don’t believe your problem lies there as from your answer concerning the other controls not being adversely effected . The same goes for both the sea clutter and fine tune control circuits and these are the circuits I would look into re-centering. Once the circuits are readjusted on the board (center re-tuned) you most likely will have more control of those functions using the tune knobs on the front of your unit.

Checking the wave guide condition is important because of the side-lobe effects of the micro-wave beams. 3 cm wavelengths are more susceptible to mismatching than are 10 cm wavelengths. And a damaged or corroded connection or piece of wave guide can give you problems when you have your unit tuned properly.

Also, you should find out what type of antenna your unit uses as the type will have a great effect on your returns if mismatched. Does it use a tilted parabolic or a slotted wave guide antenna?

 

Doug wrote:

 

But I will say this:

Decent radar units may be found for the cost of a premium sextant. And a functional radar unit is much more valuable today, than a sextant is, in every day piloting, navigation and collision avoidance.

 

Agreed. My radar unit has saved my bacon on three occasions that I can remember. Hate to part with it as it is still functional but it is only a matter of time I suppose. My season end at the end of September so I will start to think about a new radar unit...

 

Robert

 

Good luck to you Robert.