[R-390] R-390 alignment questions

[Cecil Acuff]

Hey Folks,

        I'm doing an alignment on an R-390\URR and I didn't follow the 
instructions in the manual as to inputting a signal for doing the RF 
alignment.  The IF alignment went slick...no problems. (followed the 
book..HA!)

For the RF alignment I put a signal into the unbalanced BNC cable that 
attaches to the antenna relay directly to my 50 ohm input HP-8640B.  Seemed 
the logical thing to do.  The alignment went well and the radio turned out 
to be quite sensitive on all bands...around .2-.3 uv for 10db over noise. 
Performs excellently on the air as well.

I am aware of all the cable leakage problems and what not...but the final 
product turned out ok...

I thought I would go back and input a signal on the balanced input through 
two 68 ohm resistors and set the balance trimmer for each band only to find 
the radio pretty much deaf.  Thought maybe the antenna switch was bad....and 
I still have to check that tonight but I believe now that it's more the way 
I aligned the RF deck.

My questions are this....what input do most of you use when operating the 
radio?  I know that going into the unbalanced input bypasses part of the 
tracking preselector....but it sure is easier to get a signal into the 
unbalanced input...especially since most of our antennas are unbalanced.

If I realign as per the manual am I going to be compromising performance on 
the unbalanced input to bring up the balanced input....or should I expect 
better performance by including the additional preselector stage.

Or maybe I have stumbled upon something....the radio seems to work really 
good the way it was aligned?  Just can't use the balanced input.(no loss 
here)

I assume at this point the issues are the same...390/390A.  This is the 
first time I have aligned the RF section of one of these radio's...(bet you 
couldn't guess)

I plan to go back and realign one band tonight and see what difference it 
makes.

I know using the 50 ohm generator is already a variance from the manual 
since it specifies using the URM/25 and it terminates differently.

Any suggestions are appreciated....R-1051's don't give me these kinda 
problems....

Cecil...