[Premium-Rx] Arg! Help with Alignment and test equipment set up

[Dan Rae]

Paul wrote:

>I used the IFR-1500 in Duplex mode, which
>has a spectrum analyzer and sweep function in it, to just tune up the input
>filter, the round cylinder with 4 or 5 slugs in it. Thanks to Francis et al
>who sent me the alignment instructions. Following the instructions, I am
>unable to see any change when I spin the L1 slug around at 30MHz. Nada. Zip,
>no diff. 
>
I don't know what instructions you are actually following, but the four 
coils in the A1 Low Pass Filter, in order L1 through L4, should be 
adjusted for minima at 92.35, 43.19, 40.455, and 52.3 MHz respectively, 
preferably using a spectrum analyser / tracking generator combination.  
Then the assembly should be checked for response at 30 MHz, where it 
should be no more than 1 dB down.  All this should be done with it 
terminated in 50 Ohms, of course.  

Having said that it's unlikely that this will be, or rather would have 
been, out of alignment, and the first place I'd look at lack of 
sensitivity would be the first mixer FETs, assuming everything else is 
in order.

73
Dan