This idea that everyone needs to have a tuner inline is rediculous
it is NOT needed, as a matter of fact the insertion loss of any tuner
is in the order of at least a couple db anyway. The homebrew guys
today are an endangered species!
Here is an example of an amp that will eat tuners for breakfast!
http://www.myhamshack.com/HamShackPictureViewer/10619/YC156-tank-set-for-12m.aspx
It took only a few months and some mri pulls that I knew were still
good, actually the most expensive thing is the transformer.
There is no protection circuitry, and must be connected to an already
resonant load! Or it will eat it! The only tuner I know of that won't
melt down from this beast is the collins 180Y-1, but that is a 5KW
tuner. NO! It's resonant loads ONLY at this power level. Get busy
appliance ops, and build your own dream amp and save your hard earned
money! Or if you must throw away money, buy an Alpha 9500 and at least
let it do the tuning for you. But remember it also must have an already
resonant load or things will cook - tuner or no tuner.
W2CO
On Mon, 2017-04-10 at 06:41 -0700, Jim Thomson wrote:
> Date: Mon, 10 Apr 2017 15:24:51 +1200
> From: Steve Wright <stevewrightnz@gmail.com>
> To: amps@contesting.com
> Subject: [Amps] rich Richard - tiny antenna
>
> On 10/04/17 14:20, Catherine James <catherine.james@att.net> wrote:
> > Instead, you need an expensive auto-tuner and protection circuitry, whereas
> > a tube radio is fine with a manual transmatch. I use an ATR-30, which will
> > tune just about anything.
> >
>
> What is the fixation on this list with antenna tuners? You lot are
> starting to sound like a bunch of rich appliance operators! Almost
> every thread has reference to a verrry expensive antenna tuner!
>
> Surely most multi-band yagi's, 1/4y verticals, plain ol' dipoles, and
> any other competitive HF antenna that you would WANT to poke some
> horsepower into is gonna have <1.5:1 SWR? Maybe you alligators want to
> tune up your half size g5rv on 160M or similar?
>
> It's almost as baffling as the fixation with IMD.. Isn't the goal to
> get on the air, work some DX and bend some jealous locals' S-meters?
>
> And yet, a ACTUAL constructor asks a question about a GS-35b 2M amp and
> doesn't ANY comment whatsoever!
>
> Cmon people.. Make a resonant antenna already!
>
>
> S
>
> ## You have to be a rich appliance operator to spend $7K ( $9k + tax +
> shipping in canada) for a
> lousy 1.5 kw. I wouldnt spend that kind of money on any amp..that has air
> variable
> tune + load caps either. We added up the total parts cost for that
> 3CX-6000A7
> amp I designed for a buddy a few years back, and with mostly new, and some
> used parts
> it came out to aprx $7 K. Manual tune, takes 45 secs to dial it up by the
> pre-sets, and swap bands from
> upper hf...to 160m. The new 253 lb hypersil dahl xfmer had risen in price
> though. $1600.00
> I paid $1400 for the same one, 2 years before. Rated at 15 kva CCS.
> Full qsk, covers
> warc + 60m too. Does an easy 13 kw out. At least he can say he got
> something for his $$.
>
> ## hams put the tuner at the wrong end of the coax. My upper hf yagis are
> all flat, non issue. The 40m
> yagi is less than 2:1 across the band..up to 7280 khz. Installed some vac
> relays + 1 inch wide
> silver plated strap coils in a nema box at the feedpoint, and now its dead
> flat across the 300 khz.
>
> ## the 80m rotary dipole is only 70 khz wide. Came up with this scheme to
> use a motor driven vac cap,
> but its heavy, and also had to use PWM, to slow it down, plus other issues.
> The original plan was
> a mess of dpst relays and coils to provide for 8 segments. Tossed that
> too, then went to plan C, and
> installed a seco tornado drive, which is just a pair of motor driven
> compressible .25 inch OD plastic
> tubing coils. Each coil goes from 6.25 uh to 12.5 uh... a 2: 1 ratio.
> T bar capacity hats do the main
> loading. Ok, now, on paper at least, it will cover from 3300-4000 khz with
> a flat swr, problem finally solved.
> Digital readout controller, + 10 x pre-sets, + manual up /down tuning.
>
> ## If the SS wonder amp wont deliver full power into a 2:1 swr without
> requiring the use of a tuner, its not
> designed correctly. If an amp wont do 1.5 kw cxr out... CCS, then its not
> the real deal. Its an icas rated amp.
> Being a SS amp, the switching power supply is not the issue, they are cheap.
> The diplexer is not
> the issue either. Its probably a cooling issue. A water cooled heatsink
> will be the ticket to cool these SS
> amps, as is already being done in several cases.
>
> ## $9k for lousy imd, on a par with a sweep tube amp from 1972 is not in
> the cards for me. Nor is junk like
> a K3 xcvr with equally lousy TX IMD..deal breaker right there.. at –23 dbc.
> I also looked at the yaesu 9000 xcvr, the 400watt
> version, and it has the absolute worse IMD of any xcvr ever produced bar
> none, well below any sweep tube amp.
> -13 dbc for IMD-3 . Wtf are they playing at ?
>
> ## You had better have deep pockets if you have to ship any of the above
> outside the country to get it repaired.
>
> Jim VE7RF
>
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--
Sent from W2CO
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