[R-390] R390 progress 6AK5/6AJ5

[Roy Morgan]

At 09:35 PM 5/2/2005, Flowertime01 at wmconnect.com wrote:
>Dan Merz,
>Start hanging a DC volt meter on the diode load. You are looking for -7 
>volts....
>Hang a 600 ohm 1 watt resistor on the audio output and an AC volt meter with
>a DB scale across the audio output and resistor....
>If you have more than -7 volts (with the BFO off) back the signal drive down
>or reduce the DC gain in the IF deck.

Above is a very succinct "how-to" for quick and useful results. You can't 
go far wrong with that, and this point may be very important:
>or reduce the DC gain in the IF deck.

I suggest you set the IF gain with the procedure on Chuck's site, "Setting 
IF Gain for Optimum Performance":
http://www.r390a.com/index_1.htm
and specifically at:
http://www.r390a.com/html/gain.html

Two things may have been done to your radio by some dumbhead to "make it 
hotter":
  - crank up the IF gain
  - put high gain tubes in the thing instead of what should be there.

Undo them both.

Notice again Rogers suggestions on how to know what's going on in side your 
radio:

>Start hanging a DC volt meter on the diode load. You are looking for -7 
>volts....
>Hang a 600 ohm 1 watt resistor on the audio output and an AC volt meter with
>a DB scale across the audio output and resistor....

These two functions could be built into a small box: two panel meters, one 
for diode load voltage and one for audio output.  In a  well stocked junque 
boxe you can unearth a couple of meters of just the right scale markings 
and a nice slope-fronted box to mount them in. Label the thing "R-390 
Series Receiver Test Boxe"  Add a nice long shielded cable with spade tips 
on it and you can wrestle the radio around all over the bench and not knock 
over your meters.

(Note to self: Follow own advice. Head for Junque Boxe asap.)

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-948-6213
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