[R-390] Re: R390A meter movment current.

[David Wise]

For what it's worth, I spent some time mulling over the
schematics some time ago and came to the conclusion that
unless you are willing to (a) hack the IF deck in a way
that makes it incompatible with the stock carrier meter,
and (b) put up with some degradation in AGC performance,
your only choices are either the stock meter or an amplified
one like Jan's.  Jan did a fine job, but he worked a
bit too hard: as long as the replacement meter can be
calibrated to read full-scale under the appropriate
conditions, it's not necessary for the replacement
meter or circuit to have an 18-ohm impedance.  It
can be literally anything, from zero to infinity.
The key is the product of full-scale sensitivity
and resistance.  The circuit generates so little
voltage that most meters don't get enough current
through them to go full-scale.  I don't remember the
details now, but I think I worked out how they could
have done it in a way that would work with most any
meter, but it would have cost them an extra tube,
so you know how far *that* idea got.

HTH,
Dave Wise

-----Original Message-----
From: DW Holtman [mailto:future212 at comcast.net] 
Sent: Wednesday, October 12, 2005 3:09 PM
To: Flowertime01 at wmconnect.com; r-390 at mailman.qth.net
Subject: Re: [R-390] Re: R390A meter movment current.

Roger,

Keep the group informed asw to what you find. It is a problem, many of
us face.

73's
DW Holtman
WB7SSN

----- Original Message -----
From: <Flowertime01 at wmconnect.com>
To: <r-390 at mailman.qth.net>
Sent: Wednesday, October 12, 2005 1:34 PM
Subject: Re: [R-390] Re: R390A meter movment current.


> Fellows,
>
> I need to thank you all for input on this subject.
>
> I am almost sorry I kicked this can of worms.
>
> I found some nice looking meters at fair radio to install into my
Julian
> Creek less meters R390A. The meters have the correct look and size. I
am 
> now
> examining the interior guts to see what conversion will be necessary.
>
> More to follow.
>
> Roger L. Ruszkowski