[R-390] Image problem solved

[Bob Young]

I'm a medium wave DXer with two 400' LW's going through a phaser which does 
not amplify the signals, I have a 50KW station less than 10 miles from me. I 
have my antennas connected through the phaser then going to the balanced 
input with one side grounded and have no image problems. The radio is much 
more sensitive connected that way than if you use the unbalanced input. This 
and other close by stations used to overload my old phaser to the point of 
which I couldn't use it, many people use this one with no problems, the 
reason I mention this is to let you know how much RF I have here especially 
with the long antennas. I don't know if J105 and J106 were swapped although 
I suspect they were.

Bob
KB1OKL

From: Tony Casorso <canthony15 at msn.com>
To: <R-390 at mailman.qth.net>
Subject: [R-390] Image problem solved
Sent: Thursday, October 25, 2007 1:23 AM

I was using an BNC to twinax adapter which grounds one side of the balanced
connection. When I remove this and run the signal generator or antenna two 
the
balanced pins without tying one side to the chassis, I can see nothing on 
the
spectrum analyzer. That is, With thereceiver tuned to 3 Mhz and the sig gen 
at
1.5MHz, I see nothing at the input to the RF amplifier.

Looking at the schematic, they show a field change which grounds one side of 
the
balanced input but SWAPS J105 AND J106. They were not swapped in my 
receiver.
Swapping them and then going back to my adapter gives much improved 
performance.
I don't hear the 1650KHz broadcast station at 3.3MHz any more but I can 
again
see some a 1.5 MHz signal at the RF amp input when the receiver is tuned to 
3
MHz. But it is way down from before. The best performance for the 
preselector
seems to be with J105 and J106 not swapped  and neither side of the balanced
input grounded to the receiver chassis.