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

[Flowertime01 at wmconnect.com]

Dan Merz,

Sounds like you are making progress.

Start hanging a DC volt meter on the diode load. You are looking for -7 volts.
every place the procedure says tweak and measure some point, just tweak for 
maximum signal on the diode load. 

Put the scope away.
Hang a DC meter on the diode load.
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.

When the BFO is on read the AC volt meter for 1/2 watt of power. The DC volt 
meter will peg off the DC scale with over -30 volts.

When the BFO is off read around -7 volts on the DC load.

If you have more than -7 volts (with the BFO off) back the signal drive down 
of reduce the DC gain in the IF deck.

Just do all you adjustments for maximum signal on the DC load.
The goal is signal you can hear. The DC load is where you can hear it.

Set the receiver to CAL and the BFO off. Pick a 100 KC dial setting. Start at 
31 so you can adjust the transformer and the cap for maximum signal and a 
single peak.

On each band roll the KC knob around for a maximum cal signal and tweak the 
OCS trim cap for Max peak. Just monitor the DC load and peak them out.

You need to get a signal generator on the antenna and start looking at your 
signal to noise. Until you see how close to the minimum 10:1 you are. How close 
you are to the 20:1 you should have. And how close to the 30:1 you can get, 
you just have no idea if the problem is a real problem or not.

How old is the receiver?
How exact is your line voltage?
How exact was the TM reference?
How exact is your meter?
How does your meter load your circuit?
How does your scope load your circuit?

Just to many questions to mix in.

Go to the bottom line. DC load voltage and Signal to noise ratio.
Then any thing you try either makes an improvement, makes no difference, 
makes the situation worse.

Use the same test for every thing so you can at least compare the results.
You will wonder for ever about voltages on grids and is the TM correct.

At least your down to the 7Mhz band. And it sounds like your narrowing in the 
problem. Sounds as if their are some side benefits coming out of the effort 
as improved performance on other bands.

Roger KC6TRU