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Author Topic: 10 meters having problems, or is it just my antenna?  (Read 1817 times)
K2RLH
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Posts: 23




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« on: December 16, 2011, 10:18:34 PM »

We put up a 10M dipole/inverted V in the attic a couple of weeks ago. We tuned it up with our AIM antenna analyzer and it worked great - my son was getting contacts in Europe, the southern hemisphere, etc.

Then, abruptly, 10M went dead. I can still hear a couple of what sounds like telemetry stations, but otherwise no voice copy at all anywhere in the band. True day and night. Fair amount of background noise, but no intelligible signals.

I couldn't believe the band could die like that, so I've been over everything. I went up in the attic to visually inspect the antenna and it's exactly as I left it. I confirmed our LMR-400 jumper has good continuity and no short. So too with the LMR-400 that runs from the wall to the attic and the antenna. I ran the AIM analyzer and it has exactly the same curves as before. Our FT-857D isn't complaining about SWR or anything else. Listening with a broadband handheld confirms we are putting out signal, though we're so close it doesn't really say anything about propagation.

We have a cedar shake roof, so it's possible it's become moist and is shielding the antenna somewhat. But there's no snow buildup right now, and it hasn't been raining, so the most it could be would be overnight condensation.

Is 10M that dead right now? Or is there something else I should check in our equipment?

Thanks for the sanity check....
« Last Edit: December 16, 2011, 10:20:41 PM by K2RLH » Logged
K4RCH
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Posts: 18




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« Reply #1 on: December 16, 2011, 10:29:11 PM »

Yep, the band pretty much dies at night.  If the band is open, you'll generally hear the psk ops down on 28.120.  If not, you can assume the band is done for the day.

Chris, K4RCH
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ONAIR
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Posts: 1732




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« Reply #2 on: December 16, 2011, 10:32:30 PM »

We put up a 10M dipole/inverted V in the attic a couple of weeks ago. We tuned it up with our AIM antenna analyzer and it worked great - my son was getting contacts in Europe, the southern hemisphere, etc.

Then, abruptly, 10M went dead. I can still hear a couple of what sounds like telemetry stations, but otherwise no voice copy at all anywhere in the band. True day and night. Fair amount of background noise, but no intelligible signals.

I couldn't believe the band could die like that, so I've been over everything. I went up in the attic to visually inspect the antenna and it's exactly as I left it. I confirmed our LMR-400 jumper has good continuity and no short. So too with the LMR-400 that runs from the wall to the attic and the antenna. I ran the AIM analyzer and it has exactly the same curves as before. Our FT-857D isn't complaining about SWR or anything else. Listening with a broadband handheld confirms we are putting out signal, though we're so close it doesn't really say anything about propagation.

We have a cedar shake roof, so it's possible it's become moist and is shielding the antenna somewhat. But there's no snow buildup right now, and it hasn't been raining, so the most it could be would be overnight condensation.

Is 10M that dead right now? Or is there something else I should check in our equipment?

Thanks for the sanity check....
  10 was relatively quiet today.  It has been booming for a while, but every so often it will have a low.  Wait a few days and see if it comes back.
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KC4MOP
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Posts: 728




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« Reply #3 on: December 17, 2011, 05:15:44 AM »

We are not having a really big Sun Spot event as in the past. The upper bands have a little more life now.
10M is basically kinda like a day time band.
40M whimps out a lot for some grey line work. One time last week I heard a VK station S-9 and I wasn't ready to try to make contact. The amplifier wasn't on and it takes 5 minutes to warm up.
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AC4RD
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Posts: 1236




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« Reply #4 on: December 17, 2011, 05:59:17 AM »

Ten was great for a while; the last few days, even 15m has not been great, when I've had the radio on.   One GREAT way to tell what the band is up to is the IARU/NCDXF beacons.  Listen to 28.200 CW for 3 minutes--the cycle repeats every 3 minutes.  Beacon stations around the world transmit, and if you hear, say, the one in Kenya, you know 10 is open between Kenya and your area.  There are even apps you can run so you don't have to be able to read the Morse code to know which beacon is on.  :-)   It's a great resource for all the higher bands!
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2E1CLS
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« Reply #5 on: December 17, 2011, 06:01:59 AM »

Solar activity has been very low this past week and the sfi down to 121 whereas the weeks before up at 160+ this will be a big factor in the propagation for 10m.

Carl.
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M6GOM
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Posts: 861




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« Reply #6 on: December 17, 2011, 08:20:05 AM »

We put up a 10M dipole/inverted V in the attic a couple of weeks ago. We tuned it up with our AIM antenna analyzer and it worked great - my son was getting contacts in Europe, the southern hemisphere, etc.

Then, abruptly, 10M went dead. I can still hear a couple of what sounds like telemetry stations, but otherwise no voice copy at all anywhere in the band. True day and night. Fair amount of background noise, but no intelligible signals.


Yes, that is exactly how it goes. As soon it goes dark, the band drops off a cliff. In the CQ-WW-SSB contest I was having a run of QSOs with the USA and then 20 minutes after sunset, bam - nothing.
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K2RLH
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Posts: 23




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« Reply #7 on: December 17, 2011, 08:36:10 AM »

Yes, that is exactly how it goes. As soon it goes dark, the band drops off a cliff.

Yes, I'm aware of that behavior. But the band has been dead for us 24 hours a day - and that was after outstanding performance for the first week or so. That's why I'm asking... I know our setup was working great, and then it just stopped. Yet everything technically checks out.
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2E1CLS
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« Reply #8 on: December 17, 2011, 09:07:18 AM »

Yes, that is exactly how it goes. As soon it goes dark, the band drops off a cliff.

Yes, I'm aware of that behavior. But the band has been dead for us 24 hours a day - and that was after outstanding performance for the first week or so. That's why I'm asking... I know our setup was working great, and then it just stopped. Yet everything technically checks out.

As I said above + check out the latest solar forecasts vs last couple weeks.

Carl.
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N3OX
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Posts: 8852


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« Reply #9 on: December 17, 2011, 09:30:01 AM »

Periods of high solar activity are also periods of high solar variability.    Things will be great for a while and then die.   Also, fall and spring are better than winter and summer in general.  Stick it out.

10m is pretty quiet here today by comparison to, say, last month and as others have said, a lot of that is probably the lower SFI.  Some propagation software can be helpful in these instances to tell you what paths might be open with a given SFI.

Quote
everything technically checks out.

Then it still works.  Always good to have some objective measurements about the antennas.   The absolute worst is when you make an antenna improvement and the band goes flat during the project, which seems to happen to me a lot Grin   But the thing is it's hard to mess up an antenna bad enough to explain a TOTAL lack of stations on 10m, and it's pretty much impossible to kill off all reception without affecting the SWR.  This is doubly true of a good-performing, simple antenna like a dipole.

It would be possible to get SOME reduction in performance if the roof was covered in wet snow or something, but you'd notice a change in the SWR curve and the performance reduction would be moderate, not a total cut-off.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
ONAIR
Member

Posts: 1732




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« Reply #10 on: December 17, 2011, 09:44:59 AM »

Ten was great for a while; the last few days, even 15m has not been great, when I've had the radio on.   One GREAT way to tell what the band is up to is the IARU/NCDXF beacons.  Listen to 28.200 CW for 3 minutes--the cycle repeats every 3 minutes.  Beacon stations around the world transmit, and if you hear, say, the one in Kenya, you know 10 is open between Kenya and your area.  There are even apps you can run so you don't have to be able to read the Morse code to know which beacon is on.  :-)   It's a great resource for all the higher bands!
     I keep an old CB radio on in the shack, tuned to a quiet channel with the squelch up.  When 10 opens up, a roar of CB traffic breaks the squelch, and I know it's time to jump on 10!
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K2RLH
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Posts: 23




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« Reply #11 on: December 17, 2011, 10:10:13 AM »

It would be possible to get SOME reduction in performance if the roof was covered in wet snow or something, but you'd notice a change in the SWR curve and the performance reduction would be moderate, not a total cut-off.

That's what I would have expected too, but shake roofs are weird things. Being dried wood, they soak up moisture in wet weather far more than other roof types and so have a lot more variability. This is the first time I've tried an attic antenna under a shake roof so I don't know how the variability affects things.

Thanks for the feedback. I guess we'll just be patient. Meanwhile, we're building and tuning traps for 15M, then 20M, then 40M so hopefully some of those bands will be open!
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KB4QAA
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« Reply #12 on: December 17, 2011, 11:38:06 AM »

Then, abruptly, 10M went dead. I can still hear a couple of what sounds like telemetry stations, but otherwise no voice copy at all anywhere in the band. True day and night. Fair amount of background noise, but no intelligible signals.

I couldn't believe the band could die like that, .......

Believe It!  The bands change all the time and yes they go flat dead.  Check the real time propagation websites.  The last week or so the sun has gone to sleep.
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W7ETA
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Posts: 2528




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« Reply #13 on: December 17, 2011, 12:16:36 PM »

One way to check your theory that moisture on your roof is blocking reception is to use internet spotting for just 10 meters.

If there are few-no spots, especially from your area your roof is not blocking signals.

Consider that since antennas for 10 meters are small, compared to the other HF bands, you could make another wire antenna that you install in a tree.  what comes to mind is a vertical dipole or ground plane.

Best from tucson AZ

And, congrats on having a father son hobby.

Bob
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K2RLH
Member

Posts: 23




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« Reply #14 on: December 17, 2011, 12:24:24 PM »

Believe It!  The bands change all the time and yes they go flat dead.  Check the real time propagation websites.  The last week or so the sun has gone to sleep.

There was a 10-10 contest a couple of weekends ago, and my son was getting quite a few contacts and could hear people all over the band. The very next time he tried the radio (might have been the next day), I swear I thought someone had cut the coax. It was that dead.
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