I apologize for not being more clear about my observations. When Isay "dips"
I mean as measured with my antenna analyser directly at feedline- no tuner
involved.
I have about a foot folded over at the end of the legs. I think I can make
room to add 6 inches both ends. Is that worth while?
thanks
Tom
On Tue, Feb 15, 2011 at 2:32 PM, Rick - NJ0IP / DJ0IP <Rick@dj0ip.de> wrote:
> I haven't seen Tom's writing on this, Steve. I will read it. Thanks.
> You can't argue with his point.
> If the tuner is arcing across the C's, then the SWR is probably jumping all
> over the place too.
>
> The 974 is robust enough that it usually does not arc when running 100w.
> If it does, I immediately add 1/8 wavelength feedline to the feedline for
> the band that is arcing.
> It always cures the problem.
>
> At 100w level, I have found that the MFJ tuner can match a much broader
> range than the Johnson Viking (275w) Matchbox. The Johnson starts arcing,
> yet the MFJ matches the antenna and does not arc.
> At Field Day, our club used to use the Viking for years.
> It has been replaced by the 974 because we don't have to do so much
> feedline
> pruning with it as with the Viking.
> It also has the cross needle SWR bridge and watt meter built in, making it
> convenient.
> I don't know how the efficiency compares at the wild impedance areas, but
> it
> was certainly more convenient and we did not notice any poorer performance
> than in previous years.
>
> 73
> Rick
>
> -----Original Message-----
> From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> On Behalf Of Steve Hunt
> Sent: Tuesday, February 15, 2011 5:19 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Antenna follow up- asked for help in January- need
> more help.....
>
> Rick,
>
> I you use the T-match simulator at:
> http://fermi.la.asu.edu/w9cf/tuner/tuner.html
> you'll find that minimum tuner loss usually corresponds to minimum
> inductance.
>
> Tom (W8JI) has some interesting views on T-match adjustment. He argues
> that capacitor arcing due to high voltages should be of much much more
> concern than inductor heating and losses. Again, his advice is to use
> the minimum inductance possible. More here:
> http://www.w8ji.com/antenna_tuners.htm
>
> 73,
> Steve G3TXQ
>
> On 15/02/2011 21:43, Rick - NJ0IP / DJ0IP wrote:
> > Gerry, this is what MFJ states in its manual:
> >
> > "Maximum tuner efficiency is achieved with the most capacitance (settings
> > closest to 0) and the least possible
> > inductance (higher letters of the alphabet). This efficiency translates
> into
> > best power handling, broadest
> > bandwidth, and least power loss. The goal is always to operate the tuner
> at
> > the lowest Q for the LC
> > (inductance/capacitance) circuit."
> >
> > I was a bit confused about the antenna matching well at 7.025 but dips at
> > 7.500.
> > You should get it to dip at any frequency, but of course you might get
> some
> > dips better than others.
> > The problem is, the C's do not have a vernier, so it is sometimes REAL
> > sensitive when tuning.
> > That's why I put larger knobs on mine. Made it easier to fine-tune.
> >
> > Rick
> >
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--
"No matter how fast you miss, you still lose."
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