[R-390] R390A RF deck advice

Fri Jan 9 12:37:48 EST 2015

Larry,

I did not mean every slug in the whole receiver was the same.

There are just two kinds in the R390A RF deck.

Six each of an IF type and 18 of the RF type.

And you point about the oven being stuck on is a good idea to investigate.

Roger AI4NI

-----Original Message-----
From: Larry H <dinlarh at att.net>
To: Roger Ruszkowski <flowertime01 at wmconnect.com>; r-390 <r-390 at mailman.qth.net>
Sent: Fri, Jan 9, 2015 3:39 am
Subject: Re: [R-390] R390A RF deck advice

Hi Roger,  Did you mean that the IF slugs are the same as the RF slugs?  I thought they were different.

Hi Nelson,  I have a couple 390A's and the RF deck doesn't seem to get very hot around the crystal.  Maybe the oven in that one is stuck on, so it's over heating.

Regards, Larry

   From: Roger Ruszkowski <flowertime01 at wmconnect.com>
 To: r-390 at mailman.qth.net 
 Sent: Thursday, January 8, 2015 8:49 PM
 Subject: Re: [R-390] R390A RF deck advice

Nelson,

I seen some of the slot head replacement slugs back in 73 - 74 - 75 days.
We thought they were not the right type. But they did align and tracked OK.
Give yours a try if they work then OK.

You will know real quick if they will or will not work.
As all the RF and IF slugs in the R390/A are equal, find an octave that works and is up to par
in performance. Swap you new slugs into the RF cans and try and get them aligned.
The octave will either align as expected or you can believe the slugs are not correct.

27 / 39 is about a 30 % error. 
Consider your skill level and all that could go wrong. You may just want to leave it alone.

Do every thing else to the receiver and see what your sensitivity level and signal to noise ratio is.
If you have a good 25:1 overall noise ratio leave the parts alone. If you are under 25:1 and have the best tubes you can find
in the receiver then go back and do some changes.
30:1 is all you can expect 28 29 is likely.

The thought is that the 17MHZ crystal wants to be run at temperature to be on frequency.

Chances are good you can run the receiver with the heater line open.
Try it. you can always go back to heating if you find the receiver drifts too much when used under 8 Mhz.

You can zero the cal crystal even if its is run cold.
After the receiver warms up a few hours there is not likely to be a big difference in temp inside
the oven with or with out heaters.

Give it a try and see what you experience.
You cold be happy with how the receiver works for you.
If not its all reversible.

Roger AI4NI

-----Original Message-----
From: ngietz <ngietz at mymts.net>
To: r-390 <r-390 at mailman.qth.net>
Sent: Thu, Jan 8, 2015 2:50 pm
Subject: [R-390] R390A RF deck advice

Hi all, first I want to thank everyone who responded with advice about replacing 
C227 
(I think it was) in a general overhaul of this 1963 Teledyne RF deck.
Now, I have several more questions:
1)How critical are the values of the 27 ohm resistors on some of the grids?  A 
couple
are up to 36 or 39 ohms.  What effect if any would that kind of difference have 
on 
receiver operation or gain?
2)Some time ago I ordered some replacement slugs for the tuning coils and they 
came
with brass slot head screws rather than the Bristol spline screws I was 
expecting.  The 
slugs are still coded with the red and white dots.  Is there a chance I got 
incorrect slugs
or are the brass screw slugs just a late manufacturing change?
3) Does anyone disconnect the heater line on HR202?  Seems to me the crystals 
and
associated components would last longer without all that heat.  That corner of 
the
deck has the worst cluster of out-of-spec resistors etc., and I suspect the heat 
did it.
I’d guess there might be a slight effect on stability, but I’m not using it for 
RTTY.
Thanks for all your wisdom!
Nelson Gietz
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