tuning passband filters
All,
This is a solicitation for advice in tuning passband filters. The
instance at hand is a Heathkit 5400. It uses the same RF filter deck for
Rx and Tx. I thought I was aligning it correctly by using a network
analyzer on the Rx input, sweeping over the band, and taking of the
signal on far side of the filters. This seemed to work - even with a
builtin pre-amp between the Rx input and the RF-filter deck.
However when I then tried to transmit - nothing. Only one band worked
even a little bit. I then read the instructions - remove the output
drive from the RF filter deck to the output finals and tune the filters
on transmit. The re-tuning was dramatic.
First observation - the filters are not symmetrical. They tune
differently on Tx then Rx.
My question: How can the network analyzer be used to tune this rig?
Thanks - Dan
|