AM HD reception

[rbrucecarter5]

Even with an excellent AM HD receiver like the Sangean HDT1X, the little loop that they give you is totally inadequate for HD reception. No local HD signals could be heard on Dallas stations in suburban Plano.

However, the situation changed dramatically when I hooked it to a two foot tuned box loop. The Sangean is among the most sensitive AM radios I own, a real station magnet particularly on the top half of the dial. It was really tough, however, to get reliable decode on local HD, but it was successful on most of the AM stations.

Almost no HD radio owners are going to go to the trouble of making a two foot box loop - much the less bothering to retune it every time they change frequencies. So I tested with something readily available - a Terk AM advantage. It wasn't nearly as sensitive, but actually managed to lock onto HD on most AM stations. However, it still had problems with maintaining lock. To get reliable HD reception on local AM, I still need a two foot loop which is how I will use it. This is not good news, though, for the average consumer.

 

[Len14043]

Another problem you will find in your area is lightning. A severe storm obliterated WLW about 30 miles from the tower. Under ideal conditions however, the HD signal locked in at 200 miles. It would be nice to hear a report on how a graveyard performs at night in HD. I surmise that the signal would fail within 2 miles of the tower on nights when the skip is strong.

 

[Tom Wells]

Even with an excellent AM HD receiver like the Sangean HDT1X, the little loop that they give you is totally inadequate for HD reception. No local HD signals could be heard on Dallas stations in suburban Plano.

However, the situation changed dramatically when I hooked it to a two foot tuned box loop. The Sangean is among the most sensitive AM radios I own, a real station magnet particularly on the top half of the dial. It was really tough, however, to get reliable decode on local HD, but it was successful on most of the AM stations.

Almost no HD radio owners are going to go to the trouble of making a two foot box loop - much the less bothering to retune it every time they change frequencies. So I tested with something readily available - a Terk AM advantage. It wasn't nearly as sensitive, but actually managed to lock onto HD on most AM stations. However, it still had problems with maintaining lock. To get reliable HD reception on local AM, I still need a two foot loop which is how I will use it. This is not good news, though, for the average consumer.

Is the box loop inductive-coupled or capactive coupled? If it's loose-coupled and variable, have you tried inner loop phasing both ways?

My box loop needs all the connections at the binding posts re-done. It is a squashed-box with upper points, and long vertical sides.
It's from about 1924, and I use a Crosley "book" condenser at the base to tune it. My Collins R390 and 1936 Philco 116-X scream
signals from every which way when this thing is hooked up to them.

I have been able to connect longwires to various points on the balanced/unbalanced inputs, and/or the loop, cancelling signals better
than with the loop alone.

Only thing it won't do is mulit-axis cancellations, but the combinations of main-loop angle to inner-loop and phase have allowed me to pull some real muddy impaired AMs out of the mud for fun. I last sent for a QSL in 1972.


Hey! If that loop tunes too sharply, it may be suppressing sidebands enough to hurt HD reception.
Also it would be critical to tune, as you seem to have confirmed. Maybe add a wee bit of resistance in the loop to lower the Q and see if the HDs decode better!

 

[KB1OKL]

I'm also a BCB DXer and used to use a 4' tuned and balanced box loop which I still have, these kind of antennas are used by people to get transatlantic radio signals I'm sure you know, so having trouble getting local IBOC signals to lock in on a supposed sensitive radio does not bode well for IBOC. I now use a 400' LW and a 160M dipole with a Misek Phaser to null the noisy sidebands with my 390A's, 390's etc. I can also really lock onto these stations of I want to obviously but I don't see Joe Six pack using either a box loop or 2 LW's with a phaser. I picture Joe Sixpack as my 78 year old father who listens to WBZ on his clock radio at night, he has complained to me that it doesn't come in very well anymore, I wonder why?

 

[R.F. Burns]

What part of the country does old Grand Dad live in? If he's havnig trouble with WBZ IBOC has nothing to do with it. While WBZ runs IBOC I don't believe there's a 1120 Khz or 1140 Khz station running IBOC. Tell Grand that the problem is overcrowding on the AM band. Too many daytimers allowed to operate post sunset and also tell him that today's noisy environment with computers and such cause havick to the AM BCB. Funny though, I'm here near NYC and on my GE super radio WBZ comes in about the same way it always has over the past year or so. IBOC at night has had no effect on WBZ here in NYC. Another funny thing is that nobody I know has said anything negative about their reception since IBOC has been allowed to operate at night. Honestly, I wouldn't use a 78 year old males ears as a litmus test for anything. Better luck next time.

 

[KB1OKL]

My father lives 30 miles from Boston and he has excellent ears and an excellent mind, he's not basing it on how it sounds, he's basing it on how much fading he now encounters at night with the WBZ signal itself, I also live a mile from him and have noticed the same thing, it's just not solid anymore as it used to be, it sure throws the old iBlock sidebands around though. It has become unlistenable to him, they have lost a very loyal listener. Incidentally my father loves WBZ and used to brag to people about how he could receive it when he was in the service, I believe in NC. He is not a DXer at all and it does not interest him at all but he does know that you can get halfway across the country on AM radio at night as do many people. BTW he does not drink at all.

 

[R.F. Burns]

A fading carrier has nothing at all to do with IBOC modulation. When your father was in the service the AM BCB was a totally different animal. How long have you been DXing? I used to be able to receive AM stations from parts of the country which are no longer audible, thanks to deregulation. What happened to WOAI, WBAP, KXEL, KSL, or KOA? They were heard nightly here in NY. What about XERF and XEG? I used to hear XEG when WHN went off for transmitter maintainence sunday nights. I was able to null out CHUM from Toronto and XEG would come through with a listenable signal. What about the splits which were common place. St Pierre island on 1375 Khz, Radio Albania, Kvitsoy, Norway. I heard them all on the BCB. Today you're lucky to hear the heterodyne on 1521 out of Saudi Arabia. Fading on WBZ? IBOC has nothing to do with that and that is not based on an educated guess. It's based on experience.

 

[KB1OKL]

I started in 1977 and have heard most of the stations you mentioned here in MA, in fact I heard KSL my first night out on an RCA console with a LW, but it has been a long time for many of them. I did as I reported here hear R Sweden 1179 last week clearly and in English despite WHAM's IBOC.
Yes, Dxing was much better back then.

 

[Tom Wells]

Iboc does not and cannot cause fading. Grampa may have used this word to describe the same effect I have described as
sounding like a 250-w AM daytimer on a dark winter day 30 miles out in the "old" days. He hasn't nulled the hash on a perfect zero beat,
and sure can't be taught now about backlash.

What is missing is the full go-gettum 125% modulation +/- the whoops that gave everybody a big round signal.
The iboc will crash if carrier crosses zero, and by what I've heard, only WABC and WLS run a cautious 120% and have real close control
to be able to not worry. This makes em as bright as possible. Others, for sake of non-linearity or some ABC secret don't
seem to run as close to the limit, and sound dull and flat for it.

I can't for the life of me figure out why WGN must sound so. I mourn for some, any sibilant information to define words properly.

 

[R.F. Burns]

Are you saynig that the percentage of modulation effects frequency response? I'm confused here. If such was the case the Europeans must have very limited frequency response. They don't run anywhere near the levels of modulation or compression, stations in the US do. That's one of the reasons why we can hear a fairly robust carrier from some of the transatlantics, with low of no audio present at this end.

 

[amfmsw]

I'm confused how a staion at 1120 or 1130Kc would affect WBZ 1030 at all. I do know WBZ IBOC has rendered KDKA 1020Kc near useless in may areas. But I guess WINS doesn't help much eother at 1010Kc.

The AM dial is a total garbage can of noise in major markets. And skywave sees fit for them to strew their, my opinion, illegal HD stink and litter across the nation at night.

 

[w9wi]

What part of the country does old Grand Dad live in? If he's havnig trouble with WBZ IBOC has nothing to do with it. While WBZ runs IBOC I don't believe there's a 1120 Khz or 1140 Khz station running IBOC.

WHO does, though I wouldn't think they'd be strong enough east of the Appalachians to be much trouble for WBZ. What about WINS and WEPN? They're a lot closer, assuming the listener in question is in the Northeast.

 

[mimo]

As far as I know, WINS and WEPN are not running IBOC and it would be very difficult to implement on both stations.