Base Antenna Problems/Questions

[dss56]

Radio is a Kenwood 440s im original owner
Radio has been used on the Shakespeare antenna with antenna tuner for 20 yrs plus. And worked well contacts all over the world.
Kinda got out of using it but just recently went down to turn on and I think im having problems with the radio or the antenna.

This is what im trying to find out I dont have another radio to try on the antenna so here is what is happening.

measured the radio connector center to ground.

radio off 2.5 ohms
radio on 3.8 ohms

radio on 00.6 mili vots
radio on 000 VDC


Here is the problem I found.

I checked all the cables inside the house going to the SWR meter and radio and all seem to be ok.
Here is what I noticed I'm using a Shakespeare big stick 176.
I just tried the antenna cable into the radio and noticed when I do not connect the ground ferule on the pl259 and only stick the center of the connector into the radio and not have any of the antenna ground touch the signal is good.
The minute I push the connector all the way and screw the ferule on it sucks the signal right down.

Antenna is about 40 ft on the house and mast and is not easily accessible until this weekend. Will need a ladder to get up and lower the antenna and see.

Do i have a short or an open at the antenna connector pl259?
I put a fluke digital meter on the connector ohmed it out no short from center to ground. no short open
Would the symptom be bad connector at the antenna or the antenna being bad?
I thought I should of read about 50 ohms at the coax in the house end.

Either the antenna is bad or the coax connector is bad and I'm getting no center or ground up to the antenna that's my guess.

I might just get an Antron 99 and change out the antenna and new connector on the coax.

Any suggestions?

 

[RatsoW8]

I'd say the antenna system. If you've had the same antenna and coax in use for 20 years it's a good bet the issue is in one of the two. I'd start by reworking both of the PL-259's and then go from there.

 

[dss56]

Howdy

I am also suspecting the antenna or the connector on that end. Since Its a hassle to take the antenna down I thought I would do this weekend I will wait I ordered a Antron 99 $65.00 so if its the antenna I will have a replacement I would of got another Shakespeare big stick 176 but not made anymore.

Also have 80 feet of rg 213 and all new clamps so when I take it down if either the antenna or coax I will be repaired to replace either one.

Thanks for the reply

 

[W5LZ]

From the information you've supplied there's no 'sure' way of saying what the problem may be. I think that 'receives better' without both connections to the antenna being connected (that make sense) is noremal, happens with all antennas. It very basically changes that 'tuned' antenna into a simple wire as long as the feed line and antenna together.
Until you can do some checking of the antenna it's self and the connector there, you can't honestly say there's a problem there or not. If I had to guess, it's a likely spot though.
Good luck.
- 'Doc

 

[Shockwave]

I've seen at least 3 of those antennas fail over the years. Moisture somehow gets in the matching coil at the base. It starts with a high SWR only when it rains or conditions are right for due to form. Over time it becomes worse until the antenna always has a bad SWR.

It's also normal for many antennas and radios to show a near short across their connectors. This is because your ohm meter works at DC and the 50 ohm impedance is only seen at RF frequencies. The condition is called "DC grounded" since the short is only seen at DC.

 

[hotrod]

i agree with what others have said. imho if ya gotta take it down to
replace it id go ahead and replace coax also with some good lmr-400uf
or belden 9913uf.also could try coax first its cheaper to buy than a new
antenna. bad thing is if it doesnt cure your issue then you,ll have to take
the antenna down twice.

 

[dss56]

Update

Weather was so good Sunday I decided to take the antenna down. Took a bit of work doing this on a ladder. I got the antenna down and the coax seems to be ok. I shorted out the end in the basement and and used the ohm meter on the antenna end and it seemed to be ok I got continuity so both the shield and center seemed ok.

I wish there was a way to check the antenna end but i read the big stick will read open on its connector end and that is what I got.

The fiberglass was kinda rough and fuzzy. I used good leather gloves and still the fiber glass got through to my hands.

I am expecting a new Antron 99 this week and I will put that up and replace the rg8 coax with new rg 213 double shielded and hope this will cure all my antenna problems.

 

[Marconi]

Update

Weather was so good Sunday I decided to take the antenna down. Took a bit of work doing this on a ladder. I got the antenna down and the coax seems to be ok. I shorted out the end in the basement and and used the ohm meter on the antenna end and it seemed to be ok I got continuity so both the shield and center seemed ok.

I wish there was a way to check the antenna end but i read the big stick will read open on its connector end and that is what I got.

The fiberglass was kinda rough and fuzzy. I used good leather gloves and still the fiber glass got through to my hands.

I am expecting a new Antron 99 this week and I will put that up and replace the rg8 coax with new rg 213 double shielded and hope this will cure all my antenna problems.

56, I agree that the SP 176 should show an open at the feed point shield to center, it is a coaxial CF 1/2 wave dipole. I would better describe it as a coaxial sleeved dipole. It may have a small disc-cap at the feed point, but it is not an end fed 1/2 wave which should show a short at your feed point due to a matching circuit.

If this one has been up for years, then I suggest that maybe the feed line shield is the problem due to water. It can still show DC continuity, but the RF can be severely attenuated and little signal will get thru the line.

Put a dummy load with an RF meter at the antenna end and put a few watts into this line. If you don't see ~90% of the watts at the RF meter and dummy load end of the line...that is likely the problem you note. In my experiences with a similar feed line that has dried out, the SWR was very low due to loss. Of course it you catch this line full of water during a rain...then you'll likely see a bad SWR. If you watch close...you might even be able to copy faint signals that your neighbors only heard as noise.

Other symptoms of this antenna with a bottom feed point allowing water directly into the feed line is...unuasually wide bandwidth, a very quiet receive, and maybe a noticeably less TX/RX signals.

 

[dss56]

Marconi

Thanks on the dummy load try I will do that. When I took the connector of the antenna end it was tarnished out side but inside was nice and clean no tarnish and Like I stated I did a continuity test from shield toe shield and center to center all was good.

then I shorted out the end inside the shack and read the out side end and looked ok on the fluke meter.

Im going to cut open the big stick tomorrow and see if I can find anything.
I have a new antron 99 on its way and that will get installed since the big stick has been up 25 yrs plus the glass is all frayed and ruff. I think I got my monies worth on that antenna.

Going to replace the antenna and the coax, the coax was old Tandy Radio Shack rg58 bought back at the same time of the antenna.

Her is what I have been doing to make me really think the antenna is bad.

I have been using my 2 meter fiberglass antenna with my mfj 949d antenna tuner just for receive no transmit and Im getting better receive with the 2 meter because I cant get anything with the regular BS 176 and the mfj 949D I tuned both antennas and the 2 meter has plenty of receive. I just did that as a check against the BS 176.

By next week I will have the new antenna up but will get all the equipment ready for the re-install during the week.
thanks N1HGA

 

[Marconi]

Maybe you can take some pictures. I would like to see how that antenna is done. If it's as I described, or does it have a matching device in the bottom similar to the end fed A99.

I imagine the insides of this one to be a mesh sleeve sort like the shield, and folded back over the center conductor, or maybe embedded within or glued to the inside of the bottom section. The center conductor going up through the middle of the bottom section and connecting to the tip element at the ferrule in the middle of this 2 piece antenna.

I think it looks this way, because IMO SP has always referred to this one as a coaxial 1/2 wave.

If there is nothing but shield type mesh for the sleeve inside the fiberglass bottom section, then I would image the antenna could also be bad for the same reason.

Did you just notice this go bad over-night, more or less, or was the antenna sitting without working for a long period?

 

[dss56]

I have a kenwood 440 and have not used much over the years so I decided to go down the basement and try the radio and all my memory channels were gone and display going crazy so I took front of radio off and replaced the cr2032 lith battery. Of course I then tried the radio and wala no receive very low and this all leads to me replacing everything.

I have not used the radio often in the past few years as much as I should of because of the quiet bands here in Boston area.

I will take pictures of the antenna disect and will up load. I am very curious in why it is not working if the antenna is the culprit.

Gonna run the new coax rg 213 tomorrow when I get home from work and have that waiting for the new antenna.

thanks N1HGA