[R-390] R-390A help needed

[Flowertime01 at wmconnect.com]

Ray,

Like all good things you start in the middle.

You need to put 455Khz at about 150uv into the IF deck. If you have good 
bandwidth you can down load TM 11-5820-358-35 as a PDF file. Then start with 
paragraph 73 adjustment of the IF gain pot. Para 73 just tells you how to 
hook things up for the test and gain pot adjustment.

Never has any one told you that you need 30 DB difference at this point to 
get the receiver to work. It is not in print.

To get 455 into the IF deck you remove the BNC to Mini BNC adapter from the 
back panel and the 455KHz IF output cable on it. You use these parts to 
patch the signal generator into J513. Ignore all the TM stuff about test 
adapters. Just use a BNC cable to get from the generator to the IF deck. If you 
coupler is missing. Just improvise a bit of wire from the coax into the IF 
deck jack and get a ground from the coax shield to the receiver.

You want a good analog DC volt meter (any VTVM) on the diode load. You want 
600 ohms (2 1,200 Ohm 1/4 watt) across the local line output and another AC 
volt meter across the 600 ohm load.

You set the generator up for 150 uv CW into the IF deck. 
You adjust the IF gain for -7 volts DC on the diode load.
You turn on the modulation at 30%.
The local audio AC voltage must be about 16 Volts AC (1/2 watt, 26DB) 
across the 600 ohm load.

Turn the generator back to CW. the local output should go to zero volts 
(drop down 30DB). 

Until the receiver will produce 30 DB change in signal plus noise to noise 
in this test, it will never provide the needed signal to noise at the 
antenna. Nothing can be done in the RF deck to compensate for an IF and Audio deck 
that is not up to expectations. 

Expectations being 150 UV sensitivity, 30 DB difference and 1/2 watt of 
audio out of the local audio into 600 ohm load.

The exact level of 150 is not a holy grail. You just need to be at about 
this level. You can screw the IF gain around to get -7 volts. You will or will 
not have 1/2 watt out and you will or will not have a 30 DB change between 
the CW and modulation.

Swapping tubes will get you there. Alignment helps. Z501 has a 455KHz 
crystal in it. 

Back up to test point E210 and inject 455 there. at 10UV you should get -7 
volts and a 1/2 watt out. you can rock the generator through the crystal at 
.1 to get the generator to 455KHz. you can zero the BFO against the 
generator.

Once you get up to where you can get WWV at 10 or 20 MHz. you can use the 
BFO zero to null WWV into the receiver. Then you can go to CAL and pull the 
cal oscillator to null with the BFO. You can them drop the dial bezel and 
adjust the dial counter to read zero.

If you have a counter and can count your signal generator the you start on 
the other end, You set the zero adjust to center. You adjust the dial to 
have equal over run on both ends (+ - 30). You adjust the cams to align at 
7+000. You adjust the VFO to be 2,455,000 at +000 on the dial. You inject 32 Mhz 
and set the receiver to 31+000. you run the BFO to null. you set the 
receiver to CAL then you adjust the cal osc to null against the BFO.

Then you can go and do a mechanical alignment of the RF deck and start 
swapping tubes in the RF deck until you get the whole receive up to par.

Hope this get you going it the right direction. Check out the web pages at. 
http://r-390a.net
http://r-390a.net/Pearls/index.htm
http://r-390a.net/Y2K-R3/index.htm

A must read is Wei-Li's Pearls of Wisdom. He has been collecting and 
categorizing the wisdom which flows through the R-390A mailing list. The Y2K 
manual is so much better reading than the original TM. You can pop it open in 
sections. If you are on dial up like me, it is so much faster to access than 
the big PDF documents.

Roger Ruszkowski AI4NI 33C4H</HTML>