Indeed, this is exactly what I was talking about... it's basically a CLC pi
network. The LDG is very similar internally, except that they use a L
network, and switch the C from one end to the other depending on the
impedance ratio.
No data on prices on the hfpower web site. I suspect that this isn't an
inexpensive unit (>$1K if I were to guess)..
I like the idea of optical fiber interconnect. now that you can buy premade
optical cables for less than coax, it's a great way to solve the problem of
common-mode, "ground level shifts,loops" and EMI/EMC. Another approach would
be to use standard CAT5 type 100BaseT ethernet, which is transformer
isolated, although I don't know how immune it would be to strong RF fields.
Just this morning, I was thinking that something like a big steel NEMA 4
Hammond Box with a ethernet microcontroller to generate the control signals
for relays, etc., and send telemetry back, a very well filtered DC feed with
a DC/DC converter inside the box, and an optical or RF link would be a good
start. You could put almost any sort of tuning apparatus inside the
enclosure. The control stuff would be in a subenclosure for EMI/EMC.
However, it wouldn't be cheap... those NEMA 4 enclosures are $100+, even for
small ones (12x12x6).. a more useful size 20x16x8 is $320 (based on a quick
check in the Grainger catalog)
Assuming that you can't use surplus components, you're looking at a couple
of capacitors and an inductor at around $100 each, plus a suitable drive
motor and electronics (probably another $100 or so, per drive), for $600.
Multiple relays and fixed components would probably be a bit less expensive
(figure 8 L's, 16 C's, 24 relays and drive electronics, but the L and C are
in the few dollar range, as are the relays..)... well maybe not all that
much cheaper.. 24 things at $5 each is $500
The controller would be $100-200, plus the optical or RF interface (another
$100).
A decent DC/DC power supply which operates over the temperature range and is
well filtered is probably $50
Then, you'd need 4-8 hours of assembly labor to drill holes, weld brackets,
etc., for another couple hundred dollars (figuring a burdened (taxes,
utilities, insurance, etc.) cost of $25/hr for shop time)
That makes your "out the door" cost around (300+600+150+100+50+200) = $1400,
before you add profit,shipping, development and design costs, etc. As a
rule of thumb, we used to figure that the "undiscounted retail price" of a
product would need to be 5-10 times the parts cost, depending on the level
of integration. In this case, the undiscounted retail price might be only
3x...(allowing for discounting to retail sales folks, etc.)
Is anyone really willing to pay $3000 for a state of the art remote antenna
tuner? (other than a broadcast installation, where they DO pay this kind of
money)
Yes, one COULD build it a lot cheaper in small quantities if you used
scrounged surplus components, counted your labor as free, etc., but that
wouldn't be a "product". I, among others, I'm sure, has fallen into the
trap of designing something based on surplus components, and found the
components no longer available when it came to putting it into production.
Jim, W6RMK
----- Original Message -----
From: "Jeff Stai WK6I" <wk6i@twistedoak.com>
To: "Jim Lux" <jimlux@earthlink.net>; <towertalk@contesting.com>
Cc: <k5uj@hotmail.com>
Sent: Saturday, November 29, 2003 8:51 AM
Subject: Re: [TowerTalk] Best tuner value? (I think that was the topic)
> At 05:55 PM 11/28/2003, Jim Lux wrote:
> >Alas, there aren't sufficient folks lining up to buy such a clever tuner
> >controller, so even though the parts cost would be low, the development
cost
> >would be high (say, 40K-50K, if you paid someone to do it). Are there
500
> >potential sales out there? I thought not.
>
> this looks like something in that direction, stumbled into it the other
day:
>
> http://www.hfpower.com/new/03at.htm
>
> but there are no reviews on eham - anyone actually seen one?
>
> thanks! - jeff wk6i
>
>
> --
> Jeff Stai jds@twistedoak.com
> Twisted Oak Winery http://www.twistedoak.com/
> Rocketry Org. of CA http://www.rocstock.org/
> Amateur Radio WK6I
>
>
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