[R-390] Meters

[Roy Morgan]

On Sep 5, 2009, at 8:09 PM, <ka9egw at britewerkz.com> <ka9egw at britewerkz.com 
 > wrote:

> I have obtained some NOS 1mA FS meters in the correct form factor  
> for the
> 390 panel meters.  What do I have to do to use them in my meterless
> Collins-built 390A?  I've heard it's not as simple as just  
> installing them
> and tweaking a couple pots...

KE9EGW.

here is a brief summary of your situation:

- Good scans of the R-390A meter faces are available, and most meters  
of the sort can be opened up to put in a new scale.   You may have to  
make special tool if the meters you have are put together with the  
ring type fastener instead of small screws.

- ONLY the line level meter is a candidate for replacement with the  
meters you have, UNLESS you make a most-likely solid state amplifier  
for the RF level meter.  The line level meter is a VU meter, it runs  
on AC and your meters can be made to run well with a little rectifier  
and most likey a dropping resistor or two.

- The RF level meter is both much more sensitive than the line level  
meter, AND it has a particular, odd, and unique internal resistance.   
All that combined makes it run correctly with the circuits in the  
radio.  Building a solid state "signal conditioner" circuit is quite  
feasible.  Someone must have done this already, and if so other guys  
on the list will no doubt offer further information.

If nothing further shows up on the list or in your mailbox, let me  
know.  I no doubt have further information in the archives here (I do  
have the meter face graphic files.)

Good luck,

Roy

Roy Morgan
k1lky at earthlink.net
529 Cobb St.
Groton NY, 13073
Home: 607-898-3607
Cell: 301-928-7794