Hi All, I was discussing this thread with a microwave engineer on 75 meters this morning and he reminded me that I had AM RF in my RX antennas at my previous QTH. So much that I used Hi-Pass filters on my beverages and pennants.
Terry, Do you have an AM radio station near by that could be messing with your instruments? Just a thought. GL, de George, K8GG > 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 >> > > > > > >> > > > > > ð >> > > > > > _________________ >> > > > > > Topband Reflector Archives - >> http://www.contesting.com/_topband >> > > > > > >> > > > > > > >> > > > > > > > > > _________________ >> > > > > > >> > > > > > > > > > > Topband Reflector Archives - >> http://www.contesting.com/_topband >> > > > > > > > _________________ >> > > > > >> > > > > > > > > Topband Reflector Archives - >> http://www.contesting.com/_topband >> > > > > > _________________ >> > > > >> > > > > > > Topband Reflector Archives - >> http://www.contesting.com/_topband >> > > > >> > > >> > > > > _________________ >> > Topband Reflector Archives - >> http://www.contesting.com/_topband >> > >> > > _________________ >> Topband Reflector Archives - http://www.contesting.com/_topband >> > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > _________________ Topband Reflector Archives - http://www.contesting.com/_topband