[R-390] R-390A mounting position

Tue, 20 Apr 2004 08:52:31 -0400

Hi Joe &  List

May not be such a good idea to operate an R-390 at 45 degrees, or even a
smaller angle.

The mechanics -- particularly slug racks, cam followers and the slugs
themselves -- may rub against rear mating surfaces or pull at a slight angle
vs. full vertical position.  This may also contribute to a slight
misalignment of gear shafts as they will tend to shift rearwards, etc.
Parts will also mesh or ride somewhat off the wear-in positions.

For example, the slug racks have some fore-aft play and will shift rearward.
The back surfaces of the racks (with the cam followers) will tend to rub up
against the inside surface of the RF deck.  With a slight shift, the slugs
themselves will not longer be perfectly aligned with the cores and the
support springs ("springy thingies" hanging from the racks) may pull at an
slight angle to the cores.  You could correct some of this by tweaking the
lateral slug adusters -- if it is an R-390A.  If it's an R-390, there are no
adjusters.  The increased drag might be enough to feel when tuning - or
maybe not.

In addition, it's unwise to support the radio by the front panel in that
position, so you 'd have to find a way to support it from the back at that
angle.  There also may be some tubes that should be operated in a vertical
position.  Can't say whether that would adversely affect convection cooling
at 45 degrees vs. full vertical.

Again, doesn't sound like a good idea to me.  You can temporarily prop it up
and see if there's any immediate increase in drag that way -- particularly
when turning the KC knob. Worst-case -- might even be some jamming or
sticking slugs whereby a slug rack doesn't come down all the way even with
the return springs because the works are cocked   Even if not, it's probably
not a good move from a wear and tear standpoint.

My 2 cents submitted above.

Barry

----- Original Message ----- 
From: "D. ball" <[email protected]>
To: <[email protected]>
Sent: Tuesday, April 20, 2004 7:47 AM
Subject: [R-390] R-390A mounting position

> I want to mount my 390 in a 45 degree position in a homemade rack box.
Does
> anyone for see any problems? I use the radio nightly so it does get used.
>
> thanks
>
> joe
>
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