[R-390] Dead except 0 to 1 Mhz R390 non-a

Fri Mar 27 01:00:15 EDT 2015

Roger, Ed, Grayson, Larry, 
Thanks for ideas about my problem. I think I have it mostly resolved. There are some problems with the 1st and 2nd oscillator switching but that's gradually going away as I use the set. But the biggest problem was apparently the i.f. gain setting which I found by putting 150 uv in to i.f.  and measuring/adjusting diode load to -7 volts. That brought the set alive. Of course I checked most of the tubes before this and couldn't find any weak or bad tubes. I'm a little puzzled why the gain had fallen off so much and the gain pot is now about a 1/4 turn more than it was before. Anyway I appreciate the suggestions and the fact that I haven't had to pull the rf deck out. 
In my search I read some of the old Pearls and found some of my old correspondence with the group. This reminded me of some of the things I'd done 8 or 9 years back to get this set going.  I had forgotten most of the details so was again impressed with the help I got back then.  The most formidable thing I had done was pulling just the 1st/2nd oscillator box out to fix something there. I don't think I ever pulled the rf unit out.  The radio is operating ok on 40 meters at the moment so at least I have it working about as well as I expected when I turned it on last week.   Best regards, Dan

Sent from my iPad Air2

> On Mar 23, 2015, at 11:00 PM, Roger Ruszkowski <flowertime01 at wmconnect.com> wrote:
> 
> W
> Dan,
> 
> Letting these receivers just set is not a good idea.
> They like to get the mechanical switches moved around to help 
> keep the switch wiper contacts clean.
> 
> Larry pointed you to the antenna relay contacts.
> Try an antenna into the unbalanced input and see what you get.
> 
> Just .5 to 1 meg working is not a logical problem.
> So antenna relay a good place to start.
> 
> sensitivity  is so low across all bands that only the three strong AM stations get through.
> Here you are looking for crud on a tube pin.
> Pull all the tubes one by one. look for an oxidized pin. reinsert each tube a time or two 
> to cause the tube pins and socket plugs to get scraped clean.
> De Oxit helps a lot.
> Some radio Shack electronic parts cleaner is a second choice.
> Give the wire harness to deck connectors the same treatment.
> 
> Triage starts with 150 uv of 455 KHz into the IF deck with - 7 volts on the diode load
> and with 30% modulation from the signal generator almost a 1/2 watt on the local output 
> on the back panel.
> 
> You can use the R390A trouble shooting guide found several places on the web.
> The test points and tube numbers will change but the procedures follow the same sequence and test values
> 
> 
> Between CW and modulated AM you will want about 26 - 29 DB difference in level.
> 
> If you can not get this out of the IF deck and Audio deck you will never get the
> receiver up to 10: 1 over all or close to the 20:1 it will do.
> 
> Once you get the IF and Audio working you can go for MGC on the RF deck
> and then AGC on the receiver in general.
> 
> Do not give up there is nothing in the receiver that can not be fixed.
> 
> Some of your comments indicate the RF band switch may have some crud on it.
> Pulling the RF deck in your R390 is a bit more complex than doing it for an R390A
> but you may have to go there.
> Just start with the other stuff first and enough knob twisting may work the 
> band switch contacts clean enough to be OK.
> 
> Roger Ruszkowski AI4NI 
> 
> -----Original Message-----
> From: Larry H <dinlarh at att.net>
> To: Dan Merz <mdmerz at frontier.com>; R-390 List <r-390 at mailman.qth.net>
> Sent: Tue, Mar 24, 2015 12:29 am
> Subject: Re: [R-390] Dead except 0 to 1 Mhz R390 non-a
> 
> 
> Hi Dan,  Could be the antenna connection or relay, rf amp, or if amp.  Good
> luck.
> Regards, Larry
>      From: Dan Merz <mdmerz at frontier.com>
> To: R-390 List
> <r-390 at mailman.qth.net> 
> Sent: Monday, March 23, 2015 9:11 PM
> Subject: [R-390]
> Dead except 0 to 1 Mhz R390 non-a
> 
> Hi,  I haven't used my R390 for about 2
> years and decided I needed to check
> it out compared to other lesser radios I've
> been using recently.  It's been
> sitting there in the best spot in my radio area
> and other than hooking up
> the speaker it should have been ok.  It was still set
> on 80 meters where I
> used it last but when I turned it on it was more or less
> dead except I could
> tell the audio was working but no indication of signals or
> ability to peak
> noise.  I finally went down to the broadcast band and was able
> to tune in
> the three strongest local am stations between 600 and 1000 khz. 
> The
> Megacycle change knob seemed to be the key to getting it to work and it
> was
> very sensitive to position  and would become alive by moving the Mhz
> change
> knob slightly.  And it sounded ok but I think the signal level is
> somewhat
> low on the meter compared to what I remember for the one station that
> I
> listen to the most at 960 khz.  And it  suddenly goes dead  occasionally
> when
> I'm not touching the set but is revived by more or less moving the
> megacycle
> change knob slightly.  I tried the higher bands but could get no
> response on any
> band despite a lot of motion on the Mhz change knob.  Is
> there one particular
> switch that is the likely culprit?  This radio has been
> pretty reliable in the
> past after I worked it over quite a bit after getting
> it 10 years ago but I
> don't recall having any problems with switches back
> then.  I have the manuals
> but thought there might be something obvious that
> others have encountered. 
> Thanks,  Dan
> 
> 
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