DIYbanter - View Single Post - Why should someone replace ALL the capacitors on old Tube equipment?

Clifford Heath

On 15/02/17 11:08, Ralph Mowery wrote:
In article om,
says...

That's why in the past, some receivers went down to a 50KHz IF, if you
wanted a selection of filters, it was cheaper using LC circuits down
there than a bunch of crystal or mechanical filters at some higher
frequency.

So long as there is nothing 100KHz away from your desired signal,
and no two signals spaced 50KHz apart that intermodulate in your
RF front end. Imaging is a killer. Double conversion can help, but
nothing beats RF selectivity.

Some of the modern receivers are taking advantage of the availability
of devices with much better linearity and headroom, which reduces
the intermod - and they're using I/Q conversion to defeat imaging -
but they cannot achieve the performance of a good communications
receiver.

Software hacks love SDR because it makes them feel like RF experts,
but they're not.

Are mixing the $ 10 dongles and real communication receivers that use
microprocessors instead of the crystal and mechanical filters ?

Sorry, but that sentence is not English, and I have no idea what you mean.

I have a ham transceiver that uses the microprocessor instead of fixed
filters. I can assure you that it will seperate signals that are within
a KHz or less without any problems.

So do I. They can be remarkably good, but not "amazing" in any sense.