[R-390] Zero adjust

[Perry W. Remaklus]

I am looking for a replacement Zero Adjust washer. (Thanks Roger for the
discussion.)

 

Perry W1COW

 

From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net] On Behalf Of
Flowertime01 at wmconnect.com
Sent: Thursday, October 30, 2008 6:36 PM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] Zero adjust

 

Dave, 

The zero adjust shaft is a threaded bolt through a threaded nut bushing.


Turning the knob screws a bolt through the nut and pushes a clutch
assembly. 

That assembly works just like an old manual auto transmission clutch,
except the slip range is just part of a KC knob turn (30 degrees or
rotation). 

You can see the operation if you turn the receiver up on end and look in
behind the front panel from the bottom. 

You are looking for a big (1 inch dial) flat washer on the end of the
zero adjust shaft. 
This washer pushes three pins in the clutch assembly that allows the
adjustment to be performed. 

That washer is sort of "riveted" to the end of the zero adjust shaft. 

The rivet wears off and the washer falls off. 

You can get good replacement parts. If you need them ask here and see
what you get offered in direct mail. 

If you are good at it. you can file / machine / grind the shaft back and
make a new nub to hold a new washer.   

You will likely be better off getting a new zero adjust shaft with
washer in good shape, only because you do not have a good model to use
in fabricating a replacement unit. 

If that washer is on the end of the shaft and engages the three pins and
releases the clutch and you still have no zero adjust, then you likely
need to just clean the clutch. 

This is not hard to do. You just may wait until spring. You pull the
front panel, it hangs down from the wire harness. then you can flush the
whole RF gear set on the front of the receiver. 

You sort of do this out side on the picnic table on a sunny after noon. 

You hand a plastic sheet over the hanging front panel to keep the crud
being cleaned out of the gear train from collecting on the front panel
switches / meter and parts. 


Further work is very doable if required. 

Set into it on level at a time to see how far you really need to go t
fix the problem. 


Good Luck with this. 

Roger AI4NI 

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