[R-390] R-390/URR

[Bob Young]

I'm working away on 2 390's also, got one running pretty well so far, it 
really just needed a good electrical alignment, I need a couple of crystals 
for it. I haven't checked the cams yet though. The bands are uneven. I 
changed the PTO in the other one, I'm getting severe backlash, not sure why 
yet, I think the oldham coupler is hooked up ok although it didn't have 
backlash until I decided that the oldham coupler two sides needed to be 
closer together after I put it in.

I'll check mine tomorrow for those readings and see what I get on E210.

Bob
KB1OKL


From: Jim Green <jagreen3 at sbcglobal.net>
To: r-390 at mailman.qth.net
Subject: [R-390] Still deaf below 8 Mc
Sent: Saturday, October 27, 2007 3:26 PM
I'm still plugging away with my R-390/URR (Not R-309A/URR). The main  
struggle is the deafness below 8 Mc. I am following the Third Echelon  
troubleshooting procedure in TM11-5821-357-35. I've made it to Signal  
Substitution Part e IF sub-chassis tests Step 2 where the procedure  is to 
apply a modulated 2Mc signal to E-210 with the receiver in  standby mode. I 
am supposed to hear a signal in the headphones. I  hear nothing. If nothing 
is heard the procedure is to:

1) check V205 (checks good),
2) check V701 (checks good)
3) check the V701 circuit components by voltage and resistance  
measurements. All voltages seem within range except Pin 1 at -0.46  VDC 
(should be -1 VDC to -2.3 VDC). All resistances are OK except Pin  1 at 178K 
(should be 150K) and Pin 5 at 19.8K (should be 8.5K,  however the voltage at 
pin 5 is right on the money at 178 VDC).

Does anyone see any major issues with these readings? Note I'm using  a 
Fluke model 77 to take the measurements.

4) Check the vfo operation by measuring the DC voltage at E210  (measured 
0.000 VDC). The manual goes on to say: The voltage should  be between -3VDC 
and -11VDC. If the voltage outside these limits  check J223 and P723. J223 
looks OK, but the cable P723 is connected  to has a kludjy splice in it. 
When I measure the voltage from the  center pin of P723 to ground I get 
0.000 VDC. Perhaps this is OK  since it's likely an AC signal (I measured 
0.01VAC). When I measure  resistance I get a dead short to ground. Are these 
measurements normal?

Jim (KG9MM)