[R-390] VU Meter Issue...newbie on first 390a

Fri Apr 8 10:10:22 EDT 2016

They were repute to lit when they were new.

I never see it for myself, however !

73, VE2JFE

De : R. David Eagle [mailto:kb8nnu at yahoo.com] 
Envoyé : 7 avril 2016 23:52
À : Jacques Fortin <jacques.f at videotron.ca>
Cc : r-390 at mailman.qth.net
Objet : Re: [R-390] VU Meter Issue...newbie on first 390a

Nice meters!  I give you credit on the rebuild.  I really like the contrast.

Your suggestions have been noted and I may dig in to it tomorrow to see what I can figure out with the meter.

On a different note....were these meters ever lit or strictly "glow" style?

Thanks,

Dave

KB8NNU

  _____  

From: Jacques Fortin <jacques.f at videotron.ca <mailto:jacques.f at videotron.ca> >
To: 'R. David Eagle' <kb8nnu at yahoo.com <mailto:kb8nnu at yahoo.com> > 
Cc: r-390 at mailman.qth.net <mailto:r-390 at mailman.qth.net> 
Sent: Thursday, April 7, 2016 8:58 PM
Subject: RE: [R-390] VU Meter Issue...newbie on first 390a

Hi Dave,

Could be that the internal copper oxide rectifier is shot, which can explain the brown haze inside the window…

Options will be:

1.       Open it and replace the rectifier (checking the meter movement at the same time) but they are repute to be radio-active, right ?

2.       Begin chasing for another (good) meter (can take forever)…

3.       Find an other substitute meter having, say, a 100µA movement, replace that meter dial with a R-390A VU meter scale “reproduction” and re-calibrate the whole thing, using an external schottky diodes rectifier bridge to duplicate the specifications of the original meter. (Seems to be the hardest way, but can be the only feasible one).

I already succeeded to apply the option 3 because my Collins 1954 were found without meters, so I made some replicates along the years.

The ones in the picture attached have a reversed color scheme because the meters I found at a local surplus dealer had black needles.

A lot of documentation can be found on the web about “making” replacement R-390A meters anyways.

73, VE2JFE 

De : R. David Eagle [mailto:kb8nnu at yahoo.com] 
Envoyé : 7 avril 2016 19:40
À : Jacques Fortin <jacques.f at videotron.ca <mailto:jacques.f at videotron.ca> >
Cc : r-390 at mailman.qth.net <mailto:r-390 at mailman.qth.net> 
Objet : Re: [R-390] VU Meter Issue...newbie on first 390a

Thanks for the reply.  I disconnected the one side of the meter and cheked the resistance and I get 419K one way then 240K the other.....it is somewhat biased....

Maybe the meter is shot?  :(

Thanks,

Dave

KB8NNU

  _____  

From: Jacques Fortin < <mailto:jacques.f at videotron.ca> jacques.f at videotron.ca>
To: 'R. David Eagle' < <mailto:kb8nnu at yahoo.com> kb8nnu at yahoo.com> 
Cc:  <mailto:r-390 at mailman.qth.net> r-390 at mailman.qth.net
Sent: Wednesday, April 6, 2016 11:31 PM
Subject: RE: [R-390] VU Meter Issue...newbie on first 390a

Hi Dave,

If you can disconnect the two wires going to the meter, measure the meter resistance.
It should be around 7500 ohms.
If it measures open, this is bad.... Maybe the internal rectifier have failed, or worse...
A good R-390A VU meter should indicate 0VU when connected to an audio signal generator delivering 1Volt Peak at 1kHz.

73, VE2JFE

-----Message d'origine-----
De : R-390 [mailto:r-390-bounces at mailman.qth.net <mailto:r-390-bounces at mailman.qth.net> ] De la part de R. David Eagle via R-390
Envoyé : 6 avril 2016 22:23
À : 390 List <r-390 at mailman.qth.net <mailto:r-390 at mailman.qth.net> >
Objet : [R-390] VU Meter Issue...newbie on first 390a

Hello all...Today was my first day of powering up my very first motorola 390a that I have been slowly working on over the last year.  I went through and checked all tubes with my tv7 and found a couple that needed to be replaced.  Today was the day that the speaker finally got hooked up and the rig warmed up.  Much to my surprise, I was copying cw on 40 after a few gleaming moments.
One thing I noticed though, was my VU meter was not working what so ever and I have searched around for common fixes/problems but haven't turned anything up.  Is there any common problems to look for outside of replacing the meter?
Also...I noticed that the carrier meter has a film on the inside of it that is almost brown.  I am somewhat reluctant to pull it apart due to the whole radioactive particle scare, but are these easy to disassemble and clean?

Thanks in advance,
DaveKB8NNU
______________________________________________________________
R-390 mailing list
Home: http://mailman.qth.net/mailman/listinfo/r-390
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:R-390 at mailman.qth.net <mailto:R-390 at mailman.qth.net> 

This list hosted by: http://www.qsl.net <http://www.qsl.net/> 
Please help support this email list: http://www.qsl.net/donate.html