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 <k...@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 > > > > 😞 > > _________________ > > Topband Reflector Archives - http://www.contesting.com/_topband > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband