Hi,

How do you choose a I.F. when homebrewing a H.F. receiver with BFO? I
want to build a receiver that covers all H. F. amateur bands. I am a
little confused on how to pick the type of crystal filters to use.
thanks

First catch your rabbit (i.e. a filter).

That is how a certain rabbit pie recipe starts and the same is
often true of radio projects. Joe Ham comes back from the yard sale
with a pair of tubes or a large transformer and then builds a linear
around what he has found. So go look for a good SSB/AM filter and
design the rest to suite.

A good compromise is 9MHz, as you can probably get away with
single conversion. Some of the tighter spec filters are at 455kHz
however but then you will have to go the dual-conversion route. Both
work, it is simply 'horses for courses'. If you want to put a roofing
filter up front, you could try a narrow 10.7MHz from an old mobile
radio but you will still need a narrow one after it.


73 de Joe, G3LLV