built a 6m Halo today... something is not right.. but it looks good at least

[mr_fx]

Anyways I built this little beauty today...

the analyzer shows 2 reactance and 0 ohms at 51Mhz no matter how I adjust the gamma match the result is the same

the gamma match is built out of some old RG8 (the big stuff not the mini),heat shrink tubing (over the RG8 foam) and some tubing that is just big enough for the RG8 to slide into...

NOTE: I have never built a gamma match before, never felt the need to use one...


also it is about 25" x 25", give or take

 

[n0zna]

great job,73 de JW

 

[mr_fx]

great job,73 de JW

lol, it looks nice, it just does not work... so I am open to idea, I think the gamma mach might be too big

 

[midnight special]

on my 6 meter halo the halo part was not divided, it is a complete loop just not touching where i connected it to the pvc piece i had connected to the tower,, the gamma was just like yours only i didnt put the rg8 in shrink wrap, it is still up with 1.3 swr now 3 years,,,,

 

[mr_fx]

on my 6 meter halo the halo part was not divided, it is a complete loop just not touching where i connected it to the pvc piece i had connected to the tower,, the gamma was just like yours only i didnt put the rg8 in shrink wrap, it is still up with 1.3 swr now 3 years,,,,

it's not divided, he part in the middle is slightly smaller diameter aluminium, so it electrically joins the 2 halves

 

[The DB]

An X of two but 0 ohms? I'm guessing by "ohms" you mean the value of R on that analyzer?

Is it possible you have a short in the gamma?


The DB

 

[mr_fx]

An X of two but 0 ohms? I'm guessing by "ohms" you mean the value of R on that analyzer?

Is it possible you have a short in the gamma?


The DB

yes that is what I mean, and no, it's not shorted... already checked for that

 

[Captain Kilowatt]

It looks to me as if you are using a complete piece of coax for the gamma match complete with the shield and outer sheath. You should just be using the inner piece of coax inside the gamma arm. No need for heat shrink and NO shield. Just slide the inner piece of cable with dielectric inside the gamma tube.

 

[mr_fx]

It looks to me as if you are using a complete piece of coax for the gamma match complete with the shield and outer sheath. You should just be using the inner piece of coax inside the gamma arm. No need for heat shrink and NO shield. Just slide the inner piece of cable with dielectric inside the gamma tube.

Its just the center conductor, the foam and some heat shrink tubing.... no braid

 

[Captain Kilowatt]

Oh....OK. It looked like the black vinyl insulation was still on it. Must have been the heat shrink.

 

[mr_fx]

Oh....OK. It looked like the black vinyl insulation was still on it. Must have been the heat shrink.

Yes sir

 

[mr_fx]

Another thing I had noticed is if I lay a wire on the loop going to the center conductor that the analyzer will start to show something on R

 

[mr_fx]

well I think I know what is going on... I think something nearby is wacking out the antenna, reason I think this is that my SWR meter shows a 5:1 @ 51Mhz and the analyzer shows a 25:1

the meter also shows a 4.5:1 @ 54Mhz

that being said adjusting the gamma does not seem to help much, if at all...

I have also built 3 different gamma matches for this thing, some with smaller tubing, this most recent one has a much thicker gamma tube and is about 11" long, also much closer spaced than the last one

 

[mr_fx]

 

[Captain Kilowatt]

well I think I know what is going on... I think something nearby is wacking out the antenna, reason I think this is that my SWR meter shows a 5:1 @ 51Mhz and the analyzer shows a 25:1

the meter also shows a 4.5:1 @ 54Mhz

that being said adjusting the gamma does not seem to help much, if at all...

I have also built 3 different gamma matches for this thing, some with smaller tubing, this most recent one has a much thicker gamma tube and is about 11" long, also much closer spaced than the last one

Got any high power transmitters nearby....as in within a few miles? Those MFJ antenna analyzers will not read correctly in the presence of a really strong signal from a broadcast station especially AM or FM. I know a ham, well actually my former boss, who cannot use one at his QTH because he is practically in the shadow of a 100 Kw FM station and it plays havoc with his readout. The irony is that he used to be an engineer at that very station. LOL.