On Fri, 20 May 2016, gareth G4SDW GQRP #3339 wrote:

Knowing what we now know, if you were starting out again today and intent
on a completely homebrewed station, what path should we follow?

Perhaps a FET GDO, followed by (super) regen on 472kHz, to be
adapted to be the detector stage of a 455kHz IF of a 30M RX,
followed shortly by a 30m CW TX?

Personally, I'd be against the use of DSP and PCs, primarily because such
equipment embodies many millions of transistors when all the joy,
surely, comes from achievement with simple beginnings?

Even 44 years ago, when I was licensed, downconversion to 455KHz was from
the past. At the very least, I'd use a crystal filter in the HF range, if
not something even more modern.

As I've said, sometimes complicating things makes things easier. WIth a
455KHz IF, even for 80 and 40 metres, you have to fuss with image
rejection and making the front end tuning track with the oscillator.
Using a high IF, you can separate the front end tuning, yes an extra knob
but you don't have to ajdust it that frequently, and you don't have to
fuss with tracking. On the higher bands it makes things even simpler.
Start with a small ladder filter, then you can improve it later, even
changing the frequency.

In the past, simplification came from single band receivers and then later
adding converters. With broadband circuitry, one can start with a single
band, and a simple VFO, then add others later by a fancier VFO synthesizer
and more front end tuned circuits. Arrange it so you can add later. As I
think I posted in the past, if you don't use some kind of multimode
detector, you can always add those later, by shifting to useful IF
frequencies or whatever. Keep the "VFO" in a separate box, so you can
always change it, while leaving the "basic" receiver as it is.

Or take a "cheap" shortwave portable and improve it, that used to happen,
the current "cheap" shortwave portables are generally so much better than
when I was a kid. Pick the right receiver, and you end up with a
synchronous detector, which has its advantages. Pick the right one, and
you may have more flexibility in that receiver. Or buy one of those USB
gizmos for receiving TV in some countries, and use that as the detector,
so you get the advantages of DSP there, but a traditional receiver ahead
of it.

Once upon a time, people used surplus equipment, modifying it as needed,
sometimes dramatically. So why not now? Except it's consumer electronics
taht's plentiful, rather than military surplus. DSP via one of those USB
gizmos does away with lots of componenent matching for filters and
detectors.

Michael