Hi Ed,
Unfortunately I don't get any indication per the Rig Experts manual with an
open. The R/X just does not get any indication from 1982Khz all the way to
10,500+ KHz. On my MFJ-259B (old one) with a short I get at 7.234 Mhz (or
about) R=1 and X=0. Suspect the R indicates the short of course but the X=0 is
what I am looking for. I'm going to start cutting a little bit at a time and
see what happens. I have already verified the coax is not shorted with my ohm
meter till I put the gator on it so the coax appears alright.
I am wondering just how 'critical' is getting the lengths exact? One thing I
did not quite understand was why the RE said to cut for 20% lower?
Terry
KI7M
> On June 9, 2018 at 2:09 PM Ed Hughes <kg4w@comcast.net> wrote:
>
>
> Hi Terry, see page 16 of this site
> https://www.rigexpert.com/files/manuals/aa170/aa-170-manual.pdf
>
> when looking for a 1/4 wave, leave the far end of the coax under test open.
> when looking for a 1/2 wave, short the far end of the coax under test.
>
> Your 57'7" pc of would be 1/4 wave at 3750 if the vf is 87.77
> at vf .76 = 49.85 ft
> at vf .80 = 52.48 ft
> at vf .84 = 55.10 ft
>
> Set your rig expert on freq 3750 and have it in the RX mode and you
> should see something that makes sense.
>
> Good Luck
> Ed
> KG4W
> On 6/9/2018 3:55 PM, terry burge wrote:
> > 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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