[R-390] R390A

[Bob Camp]

Hi

Compared to most radios the R-390 takes more effort to tune. The drive 
system for the rf and if tuning slugs creates a significant load on the 
tuning knob.

Lubrication and cleaning of the gear train and the tuning rack 
mechanisms can reduce the amount of drag. A full blown tear down of the 
gear train can sometimes do a lot of good. That's a lot of work. I 
would not recommend it if you only have one radio. Having a second one 
handy when you reassemble the radio is *very* useful.

There should be no noticeable backlash in the tuning system. In other 
words when you turn on the BFO and tune a carrier it should not have a 
"dead spot" when you reverse the direction of tuning.

Some apparent feel of mechanical "slop" in the tuning system is normal. 
The spring driven slug racks are the source of most of it.

As long as the tuning shaft from the tuning knob to the PTO is in good 
shape you should be able to tune a signal very well. This includes CW 
signals through the narrow filter. If that is a problem then I would 
take a look at the coupling between the PTO and the tuning shaft. There 
*should* be a spring on the coupling. If the spring is missing then you 
will have a bit of a dead spot when the tuning direction is reversed. A 
spring from a ball point pen can be used to do a quick fix of the 
problem.

An intermediate fix on the tuning system is to pull the RF deck out of 
the radio. You than then do a much better job of cleaning the gears and 
tuning racks. It's not as good as a full tear down. It is a lot less 
trouble than tearing the whole gear train apart.

Before you do any significant work on the radio I would recommend 
getting a manual and reading it carefully.  There are several good ones 
you can download from the internet. People also sell them if you prefer 
a printed manual.

Hope that helps ....

	Bob Camp
	KB8TQ


On Jun 17, 2004, at 8:25 PM, fev wrote:

>
> Hello, I bought here in Argentina a R390A manufactured by Collins.
> It works good, maybe not  so good like I suppose it must work , but my
> question now is how smooth must be the tuning , in my case is a little
> hard and
> I get a little tired tuning it if I compare it with other like the 
> TS830
> or the old SX100  I have. It is posible working on it to obtain a nice
> tuning or it is like it is?
> The second problem I see or feel is that it had some play in the
> mechanismus to tune, is posible to adjust that or this is not posible?
> Maybe my question are stupid but if one of you say me that is possible
> to make the tuning better my sicological energie will be stronger to
> start with the
> restoration of this receiver.
> Thanks in advance for your comments and sorry for my not good english.
> 73´francisco viegener LU3eec
>
>
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