[R-390] Reduced 500-1000KHz sensitivity

[nryan at mchsi.com]

Hi, Barry, no, the other other Barry,

A hanging slug should be easy to fix as follows:

1. Unhook the hold down springs and remove the rack.  At this time clean any dried on grease or crud from the ways.  Examine the slugs and see if they are vertically oriented.  Gently straighten the spring wires without stretching them.  These are very fragile, so be careful.

2. Replace the rack, but don't hook the hold down springs yet.  Check that the rack ends are 90 degrees, pull rack and correct as necessary and lubricate.  Rack should have a some play from front to back.

3. Turn KC and/or MC Change knob so rack is at its lowest level.  Loosen all six of the screws that center the slugs over the coils.  Work the rack so that slugs orient with minimal friction in the coils, then snug up the screws.

4.  Lift the rack and let it drop into the coils.  It should fall without assistance from the hold down springs.  Dust slugs sparingly with talcum if needed, but never use anything else.  Once satisfied all is well, reattach the hold down springs.

Alignment may need to be checked after this procedure.  Do it carefully and sensitivity likely will improve as most receivers need alignment anyway, in my experience.

Have fun!

73 de Norman, KG4SWM

-- Any activity becomes creative when the doer cares about doing it right, or doing it better. -- John Updike


----- Original Message -----
From: Barry Williams <ba.williams at charter.net>
To: r-390 at mailman.qth.net
Sent: Wed, 16 Mar 2011 19:53:07 -0500 (CDT)
Subject: Re: [R-390] Reduced 500-1000KHz sensitivity

Joe,

One of mine has a slug that will hang up infrequently when changing mHz 
settings. I'm now in the habit of rocking the mc knob a little to settle 
the slug.


the other other Barry
> The quickest thing to check is to see that the slug racks are not hanging up and that the cam followers are in fact following the cams tightly.  there could be crud built up on the cams or rollers.  Also, check that all of the springs are attached to the slug racks.  Check the slides for lumps of crud, etc.
>
> Clean, clean, clean, oil.
>
> Joe
>
>
>
>
> --- On Tue, 3/15/11, Ian Gallimore<iangallimore at rogers.com>  wrote:
>
>> From: Ian Gallimore<iangallimore at rogers.com>
>> Subject: [R-390] Reduced 500-1000KHz sensitivity
>> To: "R-390A Group"<r-390 at mailman.qth.net>
>> Date: Tuesday, March 15, 2011, 11:05 PM
>> Hi, group,
>>
>> My 390A was purchased from Fair five or six years ago.
>> I've recently noticed a significant decrease in sensitivity
>> in the 500-1000KHz band. Other bands appear to be OK. Just
>> before this occurred, I noticed that the sensitivity could
>> be dramatically increased by turning the MHz knob a little
>> toward the 01 setting and back, but this no longer helps.
>> Has anyone else noticed this?
>> Any suggestions gratefully received.
>>
>> 73
>>
>> Ian VA3ODA