[R-390] A vs non A

[nryan at mchsi.com]

Hi, all,

The two 6082s in the power supply do run very hot.  It's important to check the 47 ohm resistors there (I think there are four of them) and make sure they are within spec.  Better yet, replace them with 5 watt ceramics and dress the leads so air circulates freely around them.

Another nice thing to do is to run the receiver at a voltage other than 125 VAC, which is pretty much the de facto voltage from the power company.  Set a variac at 115 VAC -- lower, if you like, but no lower than 110 VAC.  If a variac isn't handy, wire up a 12.6 VAC filament transformer to buck the line voltage by that amount.  There is a schematic for this on the R-390 FAQ pages.

Finally, consider Roy Morgan's suggestion of hanging a 4" muffin fan off the side of the receiver to gently draw off heat.  Some 220 VC muffin fans work on 125 VAC at a slow (and silent) speed.  

The non-A is a terrific receiver, very much worth the candle.  Enjoy!

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: Tisha Hayes <tisha.hayes at gmail.com>
To: r-390 at mailman.qth.net
Sent: Wed, 10 Oct 2012 11:34:16 -0500 (CDT)
Subject: Re: [R-390] A vs non A

I think the non A is generally a radio that is much easier on the ears to
listen to. I kick myself in the butt for not taking an offer of one that
was being sold by a restorer. The only downside I would see are the tubes
that run in near meltdown condition all the time, then again with winter
coming you need to have something to warm up the room.

There are some folks (Perry) who enjoy retrofitting the non-A (LC tuned) IF
deck into the R-390A radio.

-- 
Ms. Tisha Hayes/ AA4HA

"In this denial of the right to participate in government, not merely the
degradation of woman and the perpetuation of a great injustice happens, but
the maiming and repudiation of one-half of the moral and intellectual power
of the government of the world." -- Fredrick Douglass, 1848
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