[TenTec] Tuner for the Orion II

[Donnie Garrett]

Rick is correct!

Many years ago (some 40+) and as a young ham I built a nice home brew antenna tuner. Afterwards I connected my coaxial fed 1/2 wave 80 meter inverted vee antenna to the tuner. Low and behold it was able to tune out the reactance on 40 meters at 7.035 MHz and my transmitter was very happy to see a 1:1 SWR. Afterwards I called cw for hours on end with virtually no results. Something was defiantly wrong! 

What I learned as a young ham experimenter was that my coaxial feed line losses were so high due to the extremely high SWR now present on the coax feed line, caused by the high feed point impedance of the 80 meter antenna when being used at 7.035 MHz. 

If you do some research you will find that as the SWR goes up so does the feed line losses in coax. Actually my RF transmitted signal was pretty much being all lost thru the long run of coax due to the extremely high SWR present on the coax feed-line, again caused by the 80 meter antenna being used at 7.035 MHz. Coax feed line has rather high losses as the SWR goes up. 

This is where the real beauty of Open-Wire feed line comes into play when used with a HF multi-band antenna. With open-wire feed-line you can have a very high SWR on the open wire feed line but the feed line losses will still be very low and as long as your transmatch can still tune out the reactance your RF signal will get out!  

Since that lesson in time I have only used coax for jumper cables between my HF tuner and my transceiver / transmitter and or receivers.  

You can believe all this or not but it is fact! Trust me!

I'm not against using coax on a single band antenna but when you try to use coax on a single band dipole as a multi-band antenna your working against your self. 

I would take even plain simple 300 ohm TV twin lead over coax any day of the week when used as a feed-line on a HF multi band antenna with the exception of course a multi-band trapped antenna of which I'm not really a fan of. 

My personal preference is to use stranded 450 ohm ladder line.  

Remember there is far more to all this than just having a tuner that is capable of tuning out a high SWR ratio. 

The proof is in the pudding as the old saying goes. 

Donnie / WA9TGT for the past 47 years. 

Sent from my iPhone


On Feb 7, 2013, at 2:49 PM, "Rick - DJ0IP / NJ0IP" <Rick at DJ0IP.de> wrote:

> Steve,
> 
> A quarter wavelength long piece of wire has about 50 Ohms.
> A half wavelength long piece of wire has about 2500 Ohms.
> 
> An 80m dipole has about 50 Ohms on 80m.
> If you try to use it on 40m, it has about 2500 Ohms.
> 
> If you would like advise about a tuner, you're gonna have to be a little
> more specific than "wire antennas".
> 
> If you mean an 80m resonant dipole, fed with coax, and tuning from 80 cw to
> 75 phone, then just about any tuner on the planet will do, including the
> Orion II's tuner.
> 
> 73
> Rick, DJ0IP
> 
> 
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Steve
> MIller
> Sent: Thursday, February 07, 2013 4:38 AM
> To: Discussion of Ten-Tec Equipment
> Subject: [TenTec] Tuner for the Orion II
> 
> I am thinking of purchasing the internal tuner for the Orion II and am
> looking for comments on how well it works.   It would primarily be used to
> match the wire antennas when tuning from cw to phone segments or vice
> versa.....not to try to match wet ropes!    Thanks very much for your help
> and comments.  73 Steve N0SM _______________________________________________
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