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eHam Forums => Misc => Topic started by: KB1TBE on November 05, 2012, 08:02:14 AM



Title: Reception/Transmission Question
Post by: KB1TBE on November 05, 2012, 08:02:14 AM
I'm not on the air on a regular enough basis to be able to tell whether I have an equipment problem -or if a sudden and dramatic loss of reception from one day to the next - or even within a single day - is a normal phenomena with HF???  In example, yesterday afternoon I was enjoying a wide range of contacts all across HF.  Around dinner time I shut the rig down, returning two or three hours later to virtually no contacts across all bands - and yes, a lot of static!  I have a G5RV plus a Transworld TW 2010.  The phenomena was typical on both antennas.  It doesn't seem logical to me that the rig would act up from being shut down and then being fired up again - so is there any other explanation?  Is a total reduction in activity common to HF?  I'm in a fairly benign area for outside interference - buried utility lines and country environment, with no nearby commercial/industrial facilities.  The rig is a TS 2000, operating barefoot.  I'm not yet proficient enough to be using code so all of my contacts are voice.  Any thoughts on what I might be experiencing?


Title: RE: Reception/Transmission Question
Post by: K8AXW on November 05, 2012, 09:17:12 AM
TBE:  Welcome to the world of HF communications!  On HF the band can "go out" in just a few moments.  By the same token the band can come alive just as fast. 

After using HF for a bit you will notice that the band(s) change for one particular part of the world (or country) and another part that wasn't being heard is now coming in.

Then there is the time of the day for each HF band when it is "open" and time of the day when the band is totally dead.

This is all covered under something called "Propagation" and hundreds of books have been written about this.  It's very interesting reading and I suggest you get one or perhaps better for you, look it up on the Internet.

To make sure you haven't developed a problem, check the bands each day and see if everything is OK.  If you're radio is dead every day and all day, then you have a problem.


Title: RE: Reception/Transmission Question
Post by: KB1TBE on November 05, 2012, 10:29:01 AM
It was the lack of propagation across all bands simultaneously that had me wondering???  I understand how the loss of one or two bands is quite normal.


Title: RE: Reception/Transmission Question
Post by: AG6WT on November 05, 2012, 10:47:23 AM
That is not unusual. Sometimes the higher bands will be open all night and you can work 20 meter DX well past midnight. Other times even local work on 80 meters will poop out.

Last night around 8pm a few locals in San Francisco I know were working a friend in OR on 80m CW. The OR station started out 599 and within 20 minutes he was below the noise. Then suddenly he came back, perhaps 579, just long enough to say the band was dying and he was having a hard time copying then he was gone. Of course everything above 80m was dead too.

Something you might read up on is MUF (Maximum Usable Frequency).


Title: RE: Reception/Transmission Question
Post by: NO2A on November 07, 2012, 10:08:01 AM
20m can fool you into thinking it`s dead,just like 17,15,10m. On bands like 80/40,the noise can actually change from early night to later at night. Try listening at different times to see if there`s any difference. A few weeks back,80 was in good shape,noise was low,and I worked a station in Seattle. If the band had been noisey that would have been very difficult. Always call cq,even if you don`t hear anything. The worst that can happen is you don`t get a call.


Title: RE: Reception/Transmission Question
Post by: G3RZP on November 08, 2012, 12:47:01 AM
A solar flare can result in Dellinger fade out, where the bands go dead in a minute or two and stay that way up to 24 hours


Title: RE: Reception/Transmission Question
Post by: SWMAN on November 08, 2012, 07:00:10 AM
 I know that at times things are great on HF in the afternoon and evening up into night time one day, then the next day everything is dead on all of HF on all bands. My receiver is ok and always has been, but mother natures ways can change in a heartbeat. I just turn it off and watch TV, turn on the handie talkie or go bother the neighbors.


Title: RE: Reception/Transmission Question
Post by: WB2WIK on November 08, 2012, 08:30:26 AM
Propagation can do many things, but it's unusual for "all bands" to be dead at the same time.

When ionospheric propagation disappears on 20m and all the higher frequency bands, usually there are still signals on 40m; if not, then usually there are still signals on 80m.

A big solar flare or CME can wipe out the whole spectrum for a while, but there wasn't one yesterday or in the past few days.  80m has been open at night every night.

Did you listen there?


Title: RE: Reception/Transmission Question
Post by: KB1TBE on November 08, 2012, 04:30:27 PM
I believe that there was one station open on 80!  That still registered so pathetic with respect to the other bands that I just didn't give it much credit.  Nice to know that "it ain't just me or my rig!" I'll have to learn to be more patient.


Title: RE: Reception/Transmission Question
Post by: G3RZP on November 08, 2012, 10:36:21 PM
On the few occasions that I've operated HF from the US, it's always struck me how relatively quiet and uncrowded the bands are in comparison to operating from Europe.


Title: RE: Reception/Transmission Question
Post by: WB2WIK on November 09, 2012, 09:08:45 AM
I believe that there was one station open on 80!  That still registered so pathetic with respect to the other bands that I just didn't give it much credit.  Nice to know that "it ain't just me or my rig!" I'll have to learn to be more patient.

On the TW antenna I wouldn't expect you to really hear anything on 80m.  But the G5RV + antenna tuner should.

The only times I've not heard a LOT of 80m activity at night has been following huge solar storms, which might occur a few times a year.  There hasn't been one lately.  The band is "packed" here from about 7-8PM all through the night and the "wee" hours.  Always, except those rare occurrances when there's been a big solar storm.