[R-390] Image problem solved

[Bob Camp]

Hi

Swapping around the cables on the back of the radio can have you  
routing the signal into the "whip antenna" input when you think you  
are running with the normal antenna input. You *will* overload the  
radio if you put much of an antenna on the (unbalanced) whip antenna  
input.

Bob

On Oct 25, 2007, at 1:23 AM, Tony Casorso wrote:

> 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.
>
>
>
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