[TowerTalk] FW: In Shack Tuner Vs. Remote Tuner for Multi-Band Antennas

[Michael Tope]

Here you go, Chuck:

http://www.arraysolutions.com/Products/Remote_Tuners.htm

http://hbag.ch/en/produkte/item/anpassnetzwerk

BTW, the thing about the fan dipole that I am not sure anyone mentioned 
is that it is an ideal candidate to use with an INDOOR antenna tuner 
since the using the multiple wire pairs will more or less guarantee a 
reasonable VSWR on each amateur band for which you include a set of 
wires. By "reasonable" I mean low enough to make the mismatch loss of 
the coax (over and above the cables intrinsic matched loss) negligible. 
For example, with up to a few hundred feet of low-loss coax, a 4:1 VSWR 
at the feedpoint approximately doubles the total line loss compared to a 
1:1 VSWR, whereas the total loss is almost 10X the matched loss when the 
VSWR increases to 10:1. Thus, if your coax has 0.6 dB loss at 1:1 VSWR 
it will have ~1.2dB total loss at 4:1 VSWR and a whopping 6dB total loss 
at 10:1 VSWR. The 4:1 VSWR results in an incremental loss of only 0.6dB 
whereas the 10:1 VSWR results in an incremental loss of 5.4dB!!  It 
doesn't take much fussing around to get less than 4:1 VSWR on each band 
with a fan dipole, so if you stop there and rely on the indoor autotuner 
for the rest, you are only taking at most a 0.6dB hit in system loss 
compared to the person who fusses around to get the VSWR down low enough 
so skip using a tuner in the shack.

If you want to explore these system trades yourself, get a copy of the 
ARRL's Transmission Line Program for Windows (TLW) written by Dean Straw 
N6BV. You can pick different cable types from a pull-down menu 
(everything from RG-174 to 7/8 heliax) and then you can specify the load 
mismatch, the frequency, and the length of the cable and it will give 
you the total line loss, the mismatch loss, and the VSWR at the cable 
input. It's a very handy tool for exploring these sorts of trades.

73, Mike W4EF.....................



On 5/7/2014 1:34 AM, Chuck Smallhouse wrote:
> This interesting subject has so far has been educational !
>
> But the original subject , I thought, would be discussed about shack 
> versus remote antenna tuners, which is a design project that I am 
> interested in.
>
> My feeling is that most, if not all, antenna variable compensating 
> units (tuners), would be better served by installing them as close as 
> physical and mechanical possible to the antenna feed point, They could 
> then "Match" the antenna to 50R and allow VSWR free, and almost 
> lossless, coax to transport the signals to and from the antenna,  Of 
> course this technique/concept works best when used with multi 
> band/frequency antennas,
>
> At present I'm loath to find a QRO or better yet a QRO++, tuner 
> suitable for remote weather resistant mounting, other than the MFJ 
> 998RT, and it's only single ended.  I'd prefer one that also made the 
> conversion from balanced input to 50R output.
>
> You may skoff, but I actually have an installed B&W style, MIL Spec, 
> folded dipole, that's 180' in overall length (using MILSpec SS twisted 
> multiple strand wire) and works quite well on especially 160 meters 
> and up.  This is in spite of the 800R power resistor in the center of 
> the far leg of the B&W dipole,  I feed it with <100' of 7/8" Helix.   
> This keeps the miss match VSWR loss, caused by the coax, quite low 
> even on the higher bands.  The standing waves on the incoming 7/8" 
> coax are then tuned/matched by my HPA's auto-tuner.  I could actually 
> mount such a tuner right at the feed point balun (it probably needs to 
> be replaced with a higher powered one), or I can put the balun & tuner 
> at the end of about a 20' run of ladder line, near the bottom the 
> tower, for easier access,  BTW, this relative sort tower that holds up 
> the center of B&W. dipole, and a long boom 6M beam, is on top of a 
> small 30' hill.  This is at 5K' elevation, with mostly a negative 
> horizon. in the important directions.
>
> Q.: In keeping with the true subject of this O.T., will this be an 
> advantage over, only using the auto tuner in my PW-1 PA ?    And why 
> aren't there more remoteable, QRO, WX proof, auto tuners, on the market ?
>
> Thanks for any comments or advice,  73,  Chuck  W7CS
>