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Old August 28th 06, 07:19 AM posted to rec.radio.amateur.homebrew
Dave Platt Dave Platt is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 464
Default Book recommendation please

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).


For the primary matching stuff, that's true.

You might want to look at the sections on crystal filters... if I
recall properly, there are some filter arrangements which use an LC
match at one or both ends.

You might want to dig into the ARRL books on UHF and microwave, and
perhaps a copy of the old ARRL VHF manual (out of print but available
used).

I think, though, that you're probably out on the bleeding edge of
amateur experimentation. Not a lot of people are homebrewing VHF gear
these days, so there may not be a single book which goes into the sort
of circuitry you're interested in with an eye towards from-scratch
design work.

I'm looking right now at the ARRL VHF Manual's description of a
2-meter portable design, circa 1972 - AM transmitter and
superregenerative receiver. It's all solid-state - no tubes.
However, as with most such designs I've seen, it has quite a few
transformers in it - typically part of single- or double-tuned
resonant circuits between the stages. The design seems to do both the
tuned filtering, and the impedance matching with the same components -
not an unreasonable approach. The oscillator strips in a
commercially-built 2-meter FM repeater's transmitter and receiver I
tore apart recently use a similar approach.

If you really want a transformerless design, I'm sure it can be done,
but the necessary L/T/pi matches may end up being more difficult to
design, and trickier to tune than a more conventional
transformer-based design.

--
Dave Platt AE6EO
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