[R-390] Reception BELOW 8 MHz Dead!

[Flowertime01 at wmconnect.com]

Robert,

You need to look at the 5654 setting over in the back right corner.

As you get a week cal tone through, remember that has every harmonic in the 
HF span in it. It will mix any where and every where to bleed through.

The noise is typical most of the receiver works so most of the noise is there.
It varies all over as you are tuning the filter circuits and adjusting the 
band pass the noise can filter through. The circuit may not be DEAD. just so 
weak you cannot get an AM signal through the circuit.

Along with the first OSC 5654 also look at the first mixer a 6C4 there in 
back.
Look at the crystal oven can. It has the cal crystal and 17Mhz first mixer 
crystal in the can. It could be crud in a crystal to socket or can to octal 
socket pin.

Most likely either the mixer tube or osc tube give up on you.
Crud in tube, crystal or filter can sockets is next in line of probable cause.
Then
Look to see if a cam clamp broke and the first mixed rack is no tracking.
Look for a bad slug in the first mixer rack (not likely but possible).

Then you need to pull the RF deck and look for a cold solder joint.
Old plastic cap under there that has not yet been changed.
A resistor that has gone way high in value.

Not a serious problem. Any 4 hours should get it fixed.
Likely 30 minutes of tube checking.


Roger AI4NI
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