Lee,
Why are solid state amps so expensive?? Even the kits are lots of
dollars.? ?What makes them so?
Here is my view on this matter:
The high price of SS amps is caused by a number of factors. I will list
them, in random order:
Capacitors: SS amps are broadband, and so they require lowpass filters,
ideally one per band, although one can skimp somewhat and manage two
close-by bands with one filter. So an amp that covers all ham bands from
160 to 6m will need between an absolute minimum of 6, and an optimal
number of 11 filters. If two-section elliptic filters are used, at least
5 capacitors are required per filter, and possibly more if some value
has to be implemented by paralleling capacitors. Each of the capacitors
needs to handle roughly 1000V and 10A, to be safe and reliable, or at
least 500V and 5A, but then it has almost no headroom for slightly
elevated SWR. Such capacitors tend to cost between 10 and 20 dollars
each! So we are talking of $300 to over $1000 just in capacitors for the
lowpass filters! Add to this a few capacitors of comparable
specifications that are needed in the amplifier proper. And if the amp
includes an antenna tuner, as many or most do, add another considerable
number of them in the tuner! So a premium amp might contain $1500 just
in RF capacitors.
Homebrewers and very small companies might get away cheaper, by using
junkbox specials, Russian military surplus, or even homebrewing the
capacitors, but companies that want to produce under well controlled
conditions can hardly do that.
Inefficiency: Essentially all ham HF amplifiers you will find are class
AB designs, which tend to have an efficiency of only around 50% at
envelope peaks, dropping from there at lower parts of the envelope. Due
to still unresolved problems coupling the drains of push-pull
transistors, class AB broadband SS amplifiers are significantly less
efficient than tuned, narrowband tube-type class AB amplifiers. This is
a problem of low impedance broadband push-pull operation versus high
impedance, single-ended, tuned operation, rather than a fundamental
problem of solid state versus tubes. The low efficiency requires the use
of enough transistors to safely handle the heat, together with huge
heatsinks, copper heat spreaders, powerful fans, maybe even
watercooling. It also requires larger power supplies. These power
supplies tend to be much better than tube amp power supplies, delivering
well regulated DC voltage over a wide range of line voltages, and
usually also include power factor correction circuitry, which makes them
easier on the power lines. All this costs money.
Engineering: HF communications is a niche market, ham radio is just a
part of this niche market, and the proportion of hams buying new SS amps
is tiny. So the sales numbers of ham SS amps are very low, which means
that all engineering costs need to be absorbed by relatively few units.
So each amplifier sold carries a considerable amount of engineering costs.
Manual labor: For the same reason (small amounts sold), companies making
amplifiers or kits cannot automatize the whole production. A lot of
manual labor is used. And these days anyone who works in electronics
rightly wants to get paid a decent hourly rate. This reflects on the
price tag. Manufacture of cabinets, front panels, etc, is also more
expensive for small runs.
Rich customers: Most hams nowadays are old people, or at least adults,
not school kids. The typical ham these days is retired, has time for
playing, has worked for many years, and has earned enough money. In his
old age he wants to play radio, putting his money to good use. If he
gets interested in a piece of ham gear that costs $5000, or even
$10,000, he might just pay that price, for the joy of having that nice
piece of engineering in his shack! After all nobody can take his savings
into the grave. Use them or lose them. This has created a small but
open-handed customer base, which some companies are serving with
overpriced, luxury ham gear. Icom for example offers a $12,000 HF
transceiver. It has good specs, sure, but the practical advantage it
gives over a transceiver costing a small fraction of that is tiny, if
there is one at all. Yaesu follows with a $9000 one, and Kenwood, more
modest, "only" charges $6500 for their flagship. All these radios are
made to give rich hams a lot of knobs to play with, adorned with
gold-colored stripes and the like, while a $2000 radio already can
feature all the performance modern technology allows. And something
similar is happening with amps. Several companies are striving to offer
"no compromise" SS amps, offering 1500W CCS, fully automatic operation,
the largest possible color LCD screen (as if that was important...), one
company even has been caught advertising the large number of lines of
code in their amp's control software... In short, the companies are
trying to offer the best amps they can, with cost being no issue, to
serve this small but attractive market of well-off hams willing to spend
a lot of money for a piece of equipment they fancy. The interest in
serving price-conscious (AKA cheapskate) hams with legal-limit, simple,
straighforward, budget amps is far lower, probably because the size of
that market isn't enough to let manufacturers earn a decent amount with
small-margin products aimed at that market.
So let's home-brew! That's the essence of ham radio, anyway.
Manfred
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Visit my hobby homepage!
http://ludens.cl
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