) writes:
In the vacuum tube world,
several types of TV line finals
are reused as HF PA FINALS.



- WHAT ABOUT CRT-TYPE PC MONITORS? -



Are there solid state components there
that could do say 5 to 30W (in) at HF?

I think you'll find the big power transistors are the horizontal
output transistors, and they have very limited frequency response.
Barely up into the HF range. Not really a surprise, given they
are intended for tens of KHz useage, and nothing more. They may
also have extraneous components built in, that may get in the
way of other useage. And there may be limits on their useage
in non-pulse applications, just as sweep tubes from years ago
had limitations in linear use.

Any other power transistors may also be limited in frequency. On
the other hand, other than the horizontal output transistor there
isn't really anything special about the power transistors in a
monitor. I suspect your chance of finding suitable transistors
are just as good in any piece of consumer electronics that would
have power transistors. So it's more a case of looking in those
scrap printers and those switching supplies and even audio amplifiers,
and looking up the power transistors in the databooks to see if
they have any good frequency specs.

In the old days, tv sets were one of the few consumer electronic
equipment around, those and radios. So if you wanted to scrounge parts,
you had to go for tvs and radios. The former, if they had an
actual transformer in the power supply, could supply a nice
hefty transformer and that was likely a bigger key component
than the tubes.

Now, there is an awful lot more consumer electronics out there,
in quantity and variety. And of course, it gets scrapped. So
there is a lot more chance to find parts of the common variety.
There was nothing all that unique about tv sets, other than they
were available.

Of course, sweep tubes were used in commercial ham equipment because
they were cheap because they were used in a lot of tv sets. So long
as transistors aren't exotic, they tend to be far cheaper than tubes
were, and buying them is as easy and cheap as trying to find suitable
HF transistors in consumer electronics.

Any other components
that would fit well
in a basic CW TX?

Any consumer electronics will supply lots of capacitors and resistors
and garden variety small signal transistors. They may supply some
power transistors suitable for transmitting, but that would depend
on what is used. Some consumer electronics will still have transformers,
and those are worth grabbing. Filter capacitors for the power supply.
A lot will supply various crystals and/or crystal oscillators, though
chances are good their frequencies won't be in an actual ham band. Of
course, find enough crystals on the same frequency and you can start
making ladder filters. Lots of LEDs, and various switches (though
pushbottons are more common in some areas than toggle switches). Pull a
VCR or tv set, and you'll find tuner modules that may be useful in other
things. Any old am/fm radio will have a multi section variable capacitor,
just like the old days, though likely the newer the radio the more likely
they use varactors instead. All the audio amplifier ICs you can want,
be they in radios or on soundcards or modem cars. It just goes
on.

But other than the variable capacitors, few of the parts will be
especially exotic. If you need really high frequency transistors,
you'll have to look for things like satellite tv receivers. Though, I
once got some Mosfets out of FM preamps for car radios. The average
am/fm radio will supply ceramic filters, "narrow" at 455KHz, wide
at 10.7MHz. Find the legendary ssb CB sets in the garbage, and that
should supply a decent filter for SSB, but otherwise you aren't likely
to find narrow filters in consumer electronics. Cellphones, the older
and clunkier the better since they will have useable components, are
a treasure trove of parts, including roofing filters in the range
above 30MHz, and usually a 455KHz narrowband FM IF strip, complete
with a crystal to move from the roofing filter frequency down to
455KHz. But those narrow filters will still be too wide for
even AM. Cordless phones offer up 10.7MHz and 455KHz ceramic
filters for FM use, and again the needed crystal to get from
one IF to the other. You can often extract the IF strip as a module
and use it intact. They often use identifiable Motorola FM IF
strips, that can be reused in some other uses. At the very least,
they are a source of "gilbert cell" type mixers.

In the old days, if you wanted exotic components, you had to go for
surplus. Because no consumer electronics would have those needed
SSB filters, or even crystals to make your own filters. That's changed,
a lot more variety is available in consumer equipment.

But likely no matter what you are building, unless it's relatively
simple, you will always find some component that you can't scrounge.

Michael VE2BVW