On Thu, 21 May 2009 07:28:25 -0700 (PDT), ve2pid
wrote:
Hi to all,
Just got my new ATU. The specs mentionned:
Tunes 6 to 600 ohms (about 10:1 SWR range). 16 to 150 on 6M (about
3:1)
It sems that this is the standardized (?) way to mention
specifications...
But, since impedances have both a resistive and reactive compoment,
doses it means 6 to 600 Ohms "resistive"?
For example , if Z= 500-J800 ohm, is it 'tunable'? I have a doubt
because the impedance could also mean sqrt(500^2+800^2)=943,4 Ohms..
Thanks de Pierre
Well, a little Googleing found the missing maker and model number.
It's obviously made by LDG but which product?
http://www.ldgelectronics.com
The spec sheets aren't any more useful. I'm also rather suspicious
because ALL their products, regardless of size or technology, have the
same specification.
Well, if all else fails, I guess I have to read one of the manuals:
http://www.ldgelectronics.com/assets/manuals/Z-817Manual.pdf
No help in the Theory of Operation section.
The manual has a slightly expanded specification:
"Tunes 6 to 600 ohm loads (16 to 150 on 6M), 24 to 2400 ohms
with optional 4:1 Balun."
My guess(tm) is that they're refering to the vector sum of the complex
impedance, which is what one ends up measuring on a VSWR guess-meter.
Disclaimer: This is only a guess.
As for the proper way to specify antenna tuners, I vaguely recall a
marine band antenna tuner that we sold at Intech in the 1970's. (Not
my project). The matching range was specified as anything that landed
inside a constant VSWR circle on a Smith Chart and was limited to a
conservate 8:1 VSWR range. It also excluded any resonant antennas,
which would automatically fall outside of the 10:1 range. We also
derrated the maximum power handling spec at the 1.6MHz end to avoid
high voltage flash over. I'll dig through my box of old Intech data
sheets and manuals later and see what I can excavate.
Meanwhile, call LDG and ask.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558