broken antenna question.

[carry2018]

Greetings and happy holidays everyone. Not a newb, but don't know this answer.
I have a discone with a horizontal element and the larger cone shaped down pointed elements.
One element of the cone or lower element group just fell off.

I use it for scanning of course, but it also doubles as a over the air digital antenna for my smart tv and before my move we got at least 40 solid digital channels OTA. At my new house we are in the country and were receiving 13 strong channels which was great. Then over the last couple of weeks of winter weather, reception dropped drastically. I went outside and noticed one of the cone elements had fallen off at the mount joint, which I knew was weak when I re-installed it.

Question is, can one missing element degrade the signal across the range?

Thank you for any input. I have rescanned for channels many many times as well.

 

[carry2018]

Quick edit to the above.
I was referring to the long radial or single plain rod extending from the hub, not any extra 'element' or coil.
Hope I was confusing.

 

[K4EET]

carry2018,

A photo would help to clarify what you are talking about. But based on what you've shared, it sounds like you lost one of several of the ground plane radials. Losing one would cause the antenna's RF pattern to change to some extent. Would it cause such a drastic reduction of received TV channels as you have noted? Maybe and maybe not. If it was a radial, can you reinsert the piece that fell off into its mounting hole? It sounds like it broke off and fell to the ground. Am I right on that?

Cheers! Dave

 

[N8IAA]

Quick edit to the above.
I was referring to the long radial or single plain rod extending from the hub, not any extra 'element' or coil.
Hope I was confusing.

Sufficiently confusing.

Sounds like metal fatigue to me. The fact that you had the antenna at a different location, then moved it to another, makes me think of other factors.

One: Where you live now may have a different signal path to the towers. Trees, buildings, and other natural/man made interference.

Two: You might want to invest in a new antenna per my first sentence. Especially since you experience winter weather. Changes in seasons cause all kinds of problems for outdoor antennas.

Just my thoughts.

Larry

 

[Ubbe]

One element more or less makes no big difference. Most probably it has happened something with your coax. They don't last forever and need to be replaced after some years. The protectiv plastic might have broken and let water into the coax.

RG6 coax are cheap so buy a new lenght and inspect the antenna adaptor for corrosion, if it's easily accessable, or buy a new as well and change while switching the coax.

I'm surprised that you manage to receive any channels at all using a discone.
Did you notice that your scanner listening also got worse, or if that is still as it was before the loss of TV signal, then it might be something wrong with the splitter you are using. Try to switch outputs or coaxes from splitter to TV.

/Ubbe

 

[cmdrwill]

TV signals are Horizontally polarized. Discones are Vertically polarized. So the mismatch in polarization will have a great signal loss.

 

[majoco]

Depends on how many ground plane rods there were in the first place - one of eight won't make much difference - one of four probably will. Replace the rod at your earliest convenience depending on how it was fitted. Mine are secured with a nut'n'bolt through the ali casting and through the rod.

 

[K4EET]

Lots of good information has been stated here. Now we need to hear back from the OP, carry2018, to let us know what configuration of an antenna system they have (antenna model, coax type and length, splitter model, etc.). Some photographs might help as well. Pictures are worth a thousand words... :lol:

Cheers! Dave

 

[carry2018]

lol.. meant hope I wasn't confusing...

Thank you all for the replies and I will address them in order. The signals were satisfactory until a couple weeks ago and I noticed the radial on the ground. If I stuck that one in the ground pointing up, could it help?
j/k.

K4EET: Yes exactly. The one rod fell off the lower cone, and it was operator error as I twisted the wrong piece as I was attaching it into the threaded hole and the shaft became loose from the threaded male part.

N8IAA: Yes-sorry about the typo. Tried to solder the small male thread insert back into the rod end, but apparently not so successful. It held up in the installation up on my roof, and when freshly mounted up there, we got 14 OTA's clean and solid.
No, 9 solid, 5 intermittent. Coax is newer-less than 2 years old from the previous owners dish sat rig in a single run from my discone to my smart tv. The advice of a new one makes sense once I'm convinced the loss of one lower radial could cause breaking up of the digital signals across the bands/channels.

Ubbe: Coax is utilized from the previous dish sat with a straight run from the discone to my TV. No tap that I know of. But this needs investigating as this is a new house, we've had electricians in our basement updating a mess of stuff down there. It's all in the same time frame and now I could suspect the eletricians may have run a fresh house wire by or around this cable, if that could be a problem. The more I think of things, the more I come up with. I have not hooked up any scanners at this point, only the tv. Back in my old neighborhood, hundreds of miles south of me in a large metro area, the same antenna pulled in 30 something channels. Of course, mostly religious and shopping, but high def preaching.
I think this model, basic discone was rated for 75 to 2000. It picked a lot up, tv and scanning and also used it for computer radio scanning.

cmdrwill: Thanks for reply. That doesn't sound good. But, this discone has a horizontal part with 8 short radial (12") and lower cone part also with 8 longer radials, minus one.

majoco: That's exactly correct. 8 per section. Went out to double check the count. And the end came off that is machined pressed onto the radial rod. The rod appears to have some sort of insulation on the inside as well.

K4EET: Yes, been some great responses. And I appreciate all the valuable time you and everybody spent in looking at this. I just needed some insight whether my ham handedness caused my signal changes. Just reading this thread and site, it's apparent we can change signal strength given the weight of a fly on one of the elements. I had no real idea it could be so exact in architecture of an antenna.

Thanks for all the help so far.

 

[cmdrwill]

lol.. meant hope I wasn't confusing...

cmdrwill: Thanks for reply. That doesn't sound good. But, this discone has a horizontal part with 8 short radial (12") and lower cone part also with 8 longer radials, minus one.

Thanks for all the help so far.

But your discone antenna IS still vertically polarized. True NOT good for television reception.

 

[carry2018]

I'm sure you're correct, but my discone before this recent change was picking up 14 total, 9 solid and tvfool.com records I should only be seeing 5 main channels. But I was getting 9 different call signs OTA, but now only 5 scan in, precisely what tvfool shows.
Also, it was noted lately on one of the good channels that they were going to do some sort of alignment or something. Things change a lot on OTA now.
And at my old location as late as this summer, I was averaging 40 channels, probably 31 with the other subs. But for sure 31 call signs. My new house up until 3 weeks ago there a bouts was 9 to 14 scanned reliably. I believe this discone is fine for OTA newer digital range. Probably not at all for analog uhf/vhf, which is for all intents and purposes is defunct.
Thanks.

 

[N8IAA]

Coax is utilized from the previous dish sat with a straight run from the discone to my TV. No tap that I know of.

So, you have a 'F' connector to a PL-259 at the base of the discone. Another spot to fail. Been making and using antennas and coax for over 30 years. Some of it in northern Ohio. Familiar with hot/cold, freezing and coax/connectors being affected by rain and street salt. Including antennas.

Larry

 

[prcguy]

I had a Radio Shack Discone and one of the cone radials fell off after some time. I didn't notice any change in performance even though I know it had to degrade by a small percent.

Certain vintage RS Discones are known to have mechanical problems with elements falling off because they tried to crimp a stainless steel tubular element to a stainless steel threaded stud and the crimp just doesn't hold up. My fix was to replace all the cone elements with new threaded aluminum ones and give the whole thing a couple of coats of paint to protect the aluminum.

 

[carry2018]

@n8iaa
Sort of. It's a bnc/259 adapter which runs through a 3 foot pipe and attaches to the center conductor. I attached the antenna with 3 screws, there were holes drilled in the lower base part at the conductor threading. I filled the antenna end of the pipe with 100% silicone and mooshed it in.
I think I can find a real similar photo of my atenna if it helps at all.

Thanks

 

[carry2018]

Thats exactly what mine did. It's been 3 or 4 years and it's entirely possible I got it from Radio shack.

And I never thought that you could buy replacement radials. Guess I should check that out.

thank you.

 

[majoco]

All the ground plane radials on my commercial discone are filled with that expanding foam stuff. They appear to be 'dead' when tapping them where other antenna elements seemed to 'ring' a bit and howl in the wind, so I guess the filling is there to dampen any resonance to stop metal fatigue at the mounting point. Yours may have succumbed to that very problem.

 

[carry2018]

@majoco - Yes, mine were foamed and I can attest to that by the burning candle radial I had while trying to semi successfully solder it back on.

Anyways, it will be immensely easier to just climb up there and screw a new radial on.
The hard part is finding them. Radio shack doesn't even list a discone online any more. I will hope to find something with more online searching.

Either this discone is capable of pulling in digital tv channels or my coax is working very well as one heck of a convoluted antenna.

Thanks everybody and this is a great forum to belong to.

 

[Ubbe]

Don't bother fixing the missing element if it's the slightest work involved. If is for sure not detectable on the signal strenght meter on your TV if one of eight elements falls off. Infact maybe you will increase the signal if you remove all bottom elements so that the top elements works in horisontal mode and perhaps add maybe 5dB to the signal.

If the rod have threads it should be easy to find a fully threaded stainless steel rod and cut to the same lenght as the others. Probably cheaper than getting an original replacement rod with shipping cost added. But it will mostly be to fix its toothless smile apperance.

/Ubbe

 

[Frankhappyg]

Can buy a Tram1410 for around $30.
Solves all problems.


Sent from my iPhone using Tapatalk

 

[carry2018]

@Ubbe. Thanks. It wouldn't be that much trouble to go up there and remove the lower radials, but I intend on using a splitter and run a SDR with a dongle to my computer for SDR scanning like I did before I moved. But until I find out what proper splitter to use for a scanner/digital tv use, it would take me about half and hour to take those off and give the tv another scan. Might be worth it for the time being.
Here's a wacky thought, replace the horizontal ones with the longer cone ones. Probably wouldn't work because the elements are designed with a wave pattern or something. But I do know I need the whole antenna for good scanning results.

I've spent a few hours already looking for a replacement radial, or a online site that sells those kind of parts.
Radio shack didn't help.

Thanks again