Topband: cutting coax stubs for 80 meter 4-square

[terry burge]

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