[R-390] Restoring my '390

Fri Sep 11 21:58:26 EDT 2009

Well,
I have not been in the R-390 arena as long as most of the rest of the group
here, but I would like to say that I took Rick Mish's advice when I got my
390 back from him and it has not been off since.
Now, I think that a player in this is the quality of ac going to the radio.
 Surges, spikes and what not can not be good on the rig. And out here in the
country where I am, I have some interesting ac swings.
Several years ago, before the R-390, I put in a inverter/charger with a good
sized battery and have all of my radios and pc going thru it.

I believe that good, stable power is a plus for the 390 and after 11,500
hours as I just calculated it , it is doing as well as the day I got it.

Just my .01cents worth (as adjusted for todays economic times)

David/ WB5UOM
----- Original Message ----- 
From: <Flowertime01 at wmconnect.com>
To: <R-390 at mailman.qth.net>
Sent: Friday, September 11, 2009 6:35 PM
Subject: Re: [R-390] Restoring my '390

> Brian KA9EGW,
>
> I think 24 x 7 x 52 x 5 is a bit long. Tubes will last almost forever but
> 43,680 hours is mostly over the line. I think Rick Mish got miss quoted.
Or
> lets not take that exact statement to literal.
>
> Think about 10,000 operating hours on a good tube. For the first 720 -
> 1,000 hours you hope the thing will quite down and get stable. From 1,000
to
> 2,000 hours you hope it will quite down and get stable, because it did not
do
> it in the first 1,000 hours. Then you get about 7,000 hours of good tube
> life. Then the tube starts to get noisy from what ever its mellow point
was.
>
> If you are going to do a PM and change some tubes. Go whole hog and get
all
> the 6DC6, 6C4's, 5654's and 5759's in the IF string. Swap the in line
> 5749's off to the VFO and BFO. Move out any 6AK6's and 5814's that will
help get
> some noise out of the signal to noise ratio.
>
> Save the old tubes. If you have a couple that go noisy early, you swap and
> old less noisy tube back in and put off doing a full refresh. If you are
> mixing your best used stash into a receiver for best signal to noise with
what
> you have on hand, then a one pass alignment will get it. The used tubes
have
> been burned in. By the time you get to the alignment part, the receiver
has
> warmed up and likely stable.
>
> After installing new tubes, do an electrical alignment twice. Leave the
> receive on for a week and repeat the alignment if you can.
>
> 720 hours (24 x 30 days) after you do some tube changes, do another
> electrical alignment. The tubes will burn in and change. An alignment will
bring
> improvements. At month 2 (another 720 hours) do it again. Then you should
be
> good for out to about 9,000 operating hours.
>
> Once you start doing tubes one at a time you need to do that alignment
with
> the tube change, and again after it ages a month or so. So if you start
> swapping tubes one by one as they die, you are for every doing alignment
or
> just listening to a less than optimum receiver.
>
> In the past years, several of the Fellows who have been there done that,
> have compared tube life and power off on cycles until the filaments break.
The
> ratio is to leave the receiver on for at least 2 hours when you turn it
on.
> If you turn the receiver on for 2 hours and then turn it off, the
filaments
> will break just about the time you reach the end of the tubes useful life.
>
> Back when (68 - 75) we did a PM on a receiver each month. It got a minimum
> eyeball for blue tubes and we ask the operator if it was missing any thing
> (like a megahertz of signals). Twice a year (semi) the receiver went to
the
> shop for about 4 hours of face wash, dusting, tube checking, mechanical
> inspection and electrical alignment. We used a signal generator, AC volt
meter
> across 600 ohms (power meter) on the Local Audio output and a DC volt
meter
> across the diode load. On a good day we may have counted the VFO and BFO
with
> a counter.
>
> Good 20:1 signal to noise from tubes was a solid year. 24 x 256 = 8760
> hours. Tubes would go another year. If you were happy with 10:1 signal to
noise
> you can have 20,000 hours and more. Tubes will go almost forever. If the
> goal is grid voltage varies plate current and things do not smoke.
>
> But if you are trying to eak the weak one out of the noise, do try to keep
> tube life under 10,000 hours. Always your mileage will vary. Turn the
> receiver off when not in use. Let it warm up a 10-20 minutes before you
get into a
> contest.
>
> The R390/A's are mostly over 50 years old. Any thing that is going to age
> and burn in has done so. BBOD's are a problem. But again, rather than poke
at
> them one at a time just do them all. Get it over with and start aging a
> whole new set of replacements.
>
> One of the Fellows asked about doing this himself last week. Your time as
a
> radio repairman is easily worth $25.00 an hour. On top of that you would
> like some return on the assets of the shop equipment and mark up on parts
> inventory. A good semi PM can easily go out 8 plus hours and never get to
a wash
> and lube.
>
> I am not into painting front panels. When I think about looking at paint,
I
> prefer some other art than standard gray on metal with white trim and
black
> contrasting knobs.
>
> But if you must repaint that panel, under stand the real hours of time,
> real skill and real value added. I am making some different choices, But I
> appreciate the cost of a refinished front panel. When some Fellows ask
$1,200.00
> plus for a specific receiver setting on a specific bench and want shipping
> extra, I do not even flinch. I under stand from where they are coming and
I
> see the value in what they are offering.
>
> Thinking of the value that is added, I see why so many on this reflector
> are doing their own maintenance.
>
> Please do share your rework experience with us. Ask what ever questions
you
> need. More than one of us will offer up some ideas of how to proceed. You
> should have no trouble getting your receiver fully operational and into
> excellent alignment.
>
> Happy to have you with us.
>
> Roger Ruszkowski AI4NI
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