Hi guys and gals,
Well, to make a long story short my Rig Experts AA-170 has quite working. Looks
normal but a 56 ohm resistor at the end of the 75 ohm coax reads infinite. On
the MFJ-259b it reads 56 ohms. Check SWR and the MFJ reads 7.499.2 Mhz 1.1:1
SWR R=56/57 ohms X=0. Coax is 55' 4 3/8" long when I got very near 7500 KHz.
With the shorted coax the MFJ-259b read 7.484.2 to 7.523 Mhz, 20.2 SWR, R=2
ohms, X=0. Seems like the velocity factor is considerably higher than what was
stated to me by DX Eng.. The velocity factor is some where around 0.84401... as
best I can figure it. So I guess that makes it 0.84 VF FWIW.
Anyway, I have it figured that 55' 4 3/8" will do the trick for my 80 meter
4-Square at 3.750 Mhz.
But why my RE analyzer went out today I don't have any idea. Back to the MFJ!
Terry
KI7M
> On June 9, 2018 at 6:59 PM terry burge wrote:
>
>
> Good point Wes. I will see if I can find a decent value of resistor. My
> Rig Experts AA-170 was purchased because I did not trust the readings my
> MFJ-259b was giving me while working on my hytower. Pretty penny for these
> antenna analyzers. But I will bet if it won't do the stub frequency checks it
> won't do the velocity factor and more. Did work pretty good for checking SWR
> and feedpoint impedance on antennas like the hytower. Really liked it until
> this.
>
>
> Terry
>
> KI7M
>
> > > On June 9, 2018 at 5:11 PM Wes Stewart wrote:
> >
> >
> > Since he said the coax was 75-ohm, a 75-ohm termination would be
> > better.
> >
> >
> > On 6/9/2018 5:07 PM, Richard (Rick) Karlquist wrote:
> > > > As a sanity check, terminate the coax with a 50 ohm resistor
> > and verify
> >
> > > > > that you have good coax. Flat line at 1:1 SWR, etc.
> > >
> > > Rick N6RK
> > >
> > > On 6/9/2018 4:57 PM, terry burge wrote:
> > > > > > I don't know what is wrong here but I keep getting in
> > > this situation where my
> > >
> > > > > > > typing starts running back over my writing. I
> > > will try again to reply.
> > > >
> > > >
> > > > Joel,
> > > >
> > > > I have tried all that the manual says without success.
> > > > All I see is the
> > > > horizontal solid and dashed lines of R and X. No
> > > > indication of a resonance
> > > > point anywhere from 1880 KHz up to 10,500 KHz. Go
> > > > figure? At least my
> > > > mfj-259b is working old as it may be. Rig Experts is
> > > > going to get a nasty
> > > > note I think. Disappointing, huh?
> > > >
> > > >
> > > > Terry
> > > >
> > > > KI7M
> > > > > > > > On June 9, 2018 at 2:54 PM Joel Harrison wrote:
> > > >
> > > > > > > > > Hi Terry,
> > > > >
> > > > > I replaced the 1/4 lines on my 80 meter 4 square
> > > > > this past fall and used
> > > > > my AA-170 to set the length with no problem.
> > > > >
> > > > > Just select "all" for the mode and set the freq
> > > > > you're aiming for and then
> > > > > trim the line until X equals zero with the far
> > > > > end open. Should work fine.
> > > > > I always calculate the length x VF then add a few
> > > > > feet to start.
> > > > >
> > > > > 73 Joel W5ZN > > Hi guys and gals,
> > > > > >
> > > > > >
> > > > > > > > > > I have got DX Engineering 75 ohm foam
> > > > > coax to make the
> > > > >
> > > > > > > > > > > stubs/feeders for
> > > > > > my Comtek 80 meter 4-Square and am finding
> > > > > > some difficulty.
> > > > > > Neither my
> > > > > > MFJ-259B nor my Rig Experts AA-170 seem to
> > > > > > indicate a 1/2 WL at
> > > > > > 7500 KHz
> > > > > > or a 1/4 WL at 3750 KHz? Or any frequency
> > > > > > up or down from there.
> > > > > > Seems to
> > > > > > me the last time I did this a few years ago
> > > > > > I didn't have a problem
> > > > > > getting a 1/2 WL dip indicating a resonance
> > > > > > location. But now I
> > > > > > just don't
> > > > > > get any indication of a resonance.
> > > > > >
> > > > > >
> > > > > > DX Engineering said they had got some 75
> > > > > > ohm foam coax that
> > > > > > instead of
> > > > > > 0.84 VF was more like 0.80 down to 0.76 VF.
> > > > > > But checking all the
> > > > > > way down
> > > > > > to 6000 KHz on 40 meters or 2500 KHz on 80
> > > > > > meters fails.
> > > > > >
> > > > > >
> > > > > > My test is to use either antenna analyzer
> > > > > > with a PL-259 installed
> > > > > > at one
> > > > > > end and an open or a short at the other. I
> > > > > > started with 57'7" of
> > > > > > coax.
> > > > > > Tried both with the coax in a roll and
> > > > > > strung out. What am I doing
> > > > > > wrong?
> > > > > >
> > > > > >
> > > > > > Terry
> > > > > >
> > > > > > KI7M
> > > > > >
> > > > > > 😞
> > > > > > _________________
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