Why can I get FM and not DTV?

[SlcDX]

Here is the situation...

With my FM-6 being the only antenna I have for both FM and TV up right now, I am getting KQSW 96.5 Rock Springs, Wyoming often clear (the clearest its been is right now at this very moment) @ 152 miles via tropo, troposcatter or knife edge (I don't know the difference). It does fade out after short periods of time but comes back in.

The thing is, in Rock Springs, less than two hundred feet away from the very FM station transmitter above sits KGWR Channel 13 DT.

Why am I getting KQSW so clear yet on my DTV box there is no hint what so ever of channel 13?

Is it the FM-6 being a poor TV antenna, or does tropo/troposcatter/knife edge favor just FM for me :mad:

I have left the box on 13 for a few days and no decodes from KGWR even though I get KQSW almost daily now.

The FM-6 picks up all of my local UHF and VHF DTV stations as well as a few analogs that are local (the farthest being 43 miles).

Also, if I had both an FM-6 and my real TV antenna hooked up in series, would it effect much?

[cd637299]

Maybe I can help here....

I had to toss my old TV antenna a few months ago, and for a while, all I had was my FM-6 element.

I could be mistaken here, but it seemed that the best reception for TV was "off the back." Seemingly my best off-and-on reception of WTVX DT 34, which is due north of me, was when my FM-6 was pointed south! or near south.

It may be due to the structure of the antenna. It's worth a try to point the FM-6 the opposite way, to try to bag your wanted station(s).

Keep in mind, also, that DTV stations don't run near the power that they were allowed as analogs. Let us know how that works.

cd

[SlcDX]

Good to know. I have the FM-6 pointed away from a majority of the local TVs and they come in clear... minus one that is southwest about 40 miles.

A few minutes ago I hooked up my old Quantom FX antenna I had from the summer in series with the FM-6 and noticed no difference in TV stations decoding from before. Looks like a majority of the work is being handled by the FM-6. FM hasn't changed either with the addition of the new antenna riding piggyback.

I did see some analog Es off of the Quantom though so it can't be THAT bad. I might as well keep it up there for some time and see if I can get KGWR.

On another note, I know KGWR's coverage is weak compared to when it was analog as I have parents who live near it. When I was home testing with a set of rabbit ears, I could barely get it less than 15 miles from my house. That station is the biggest fail ever.

[Russ-PA]

For any given co-located FM and VHF DTV, presuming powers aren't minimal, the FM will propagate far further than the DTV. It's the nature of the beast.

At that distance, I wouldn't expect to see that DTV absent some decent tropo.

[Danny]

Justin, DXers don't always like my comments. The honest truth is that DXers who do well with DTV use large, expensive *TV* antennas. Analog TV was easy to DX with smaller, less-expensive, second-rate antennas. This is the reality of the brave new world of DTV DXing.

I understand that money and space are problems for many people these days. If you are serious about DTV DXing, and you have the room, maybe you can save up some money and buy a real TV antenna.

The good news is that Saul Chernos has received DTVs via *Es* on rabbit ears.

[SlcDX]

I can't afford a huge antenna though, the best I can make do with is my cheap one for now until my financial situation improves. The FM-6 actually works fairly well as a TV antenna (for locals anyway) as far as I know, but I won't know until this summer if it really can pull them in.

[indysteve]

Justin, a few months ago I was confused why a large low band TV antenna (Winegard YA-1026) http://www.solidsignal.com/pview.asp?mc=03&p=YA1026&d=Winegard-YA-1026-10-Element-Loband-Yagi-TV-Antenna-(YA1026)&c=TV Antennas&sku=615798304850 worked very well for TV channels 2-6 (analog and digital), but could barely receive some of my local and area FM stations. I then connected the FM receiver to a $5 closeout antenna (large Antennacraft UHF/VHF ant.) and immediately I was receiving FM stations up to 100-125 miles at the time.

Most antennas are channel/frequency-specific and some are designed not to pass other frequencies, like some pre-amps. I haven't owned an FM-only antenna for a long time, so I don't have one to test your issue.

Steve

[Danny]

Most antennas are channel/frequency-specific and some are designed not to pass other frequencies, like some pre-amps. I haven't owned an FM-only antenna for a long time, so I don't have one to test your issue.


Steve is correct. And yes, I have a ten-foot long FM antenna, a twelve-foot long channel 2 yagi, and a thirteen-foot long low-band (channels 2-6) yagi. I can assure you that they are all *poor* performers on the frequencies for which they were *not* designed. At the same time, they all perform well on the frequencies for which they were designed.

I also have an old-style CM 8-bay, which some people claim is good on high-band TV. Compared to my two VHF-only antennas (both low- and high-band; one is 15-feet long, the other is 16-feet long), the 8-bay stinks on the high-band.

(Unfortunately, I don't have enough space to have all of those antennas up at once.)

[Robert Grant]

I can't afford a huge antenna though, the best I can make do with is my cheap one for now until my financial situation improves. The FM-6 actually works fairly well as a TV antenna (for locals anyway) as far as I know, but I won't know until this summer if it really can pull them in.

The ironic thing about DTV is that for all the buzz about how some people have difficulty receiving DTV, it is also true that the nature of DTV can actually hide the fact that an antenna is lousy. In DTV, if the signal is merely strong enough, with not too much multipath, and with not too much interference, you will get a perfect picture, indistinguishable from what one would receive with a fine antenna aimed right at a transmitter across 2 miles of desert.

It may very well have been true that when local analog stations were still on the air, your FM-6 would have given you a mediocre signal (moderately snowy, some ghosting, and moiré patterns caused by interfetence from something in your house) from the same transmitter sites.

BTW, whenever one talks about using a complex antenna designed for one particular band (e.g., FM broadcast) for any other band, almost all bets are off. Simple relationships that work with a dipole or a vertical (odd harmonics, or add inductance if the wire is too short) fall apart when applied to more complex antennas.

One good case in point is the frustration experienced by many who tried to use UHF-only antennas in markets where at least one desirable station is on VHF. A two-bay bowtie seemed to almost work, so going to a 4-bay would make everything just hunky dory, right? WRONG, in a four bay UHF bowtie, the top and bottom bowties are connected out of phase (which assures its voltage is applied in-phase after the shorter wavelength UHF signals travel along the phasing bars), but, with longer VHF waves, the top and bottom bowties are closer to canceling out the VHF signals from the "inside" bowties. Hence, the 2-bay was actually better for VHF than the 4 bay (though, for VHF alone, a pair of windshield wipers from a 1958 Edsel would be even better!).

[cd637299]

I'll echo the above, as far as picture-perfection, if there is such a word.

Recording analog TV DX can be a nuisance, especially if you wanna put it on DVD. When I bought my first DVD recorder in 2005, I was sad to find out, that when I tried to dub my DX from VHS to DVD, almost *nothing* would show up, due to the data not being able to catch up.

Although I have yet to dub any DTV DX from my VHS to DVD, I don't think I'll see a problem....at all. With a good picture, everything goes smoothly.

cd

[Michael-NJ]

Again echoing what people have already said above, with some of my own input...

The FM-6 is cut for a specific bandwidth, with the highest gain usually near the center of the (FM) band. Will it work on other frequencies (TV) sure, but results are far from optimized with your pattern ending up being all over the place (even off the back). The reason why you can hear FM, but not see DTV is, as people above said they’re two totally different animals. Analog FM can be heard in a weak form hundreds of miles away with the right equipment, meaning a very weak signal can still give you something listenable. DTV on the other hand requires a certain amount of signal before it can even decode, meaning the threshold is much higher.

As a comparison between the two, think of it almost like a CD (DTV)… that’s digital, it can read through scratches (weak signal), but once it reaches a certain point, too much of the data is lost and you start hearing skips (breakups), or the thing won’t play at all (no decode). Now compare that to an analog record (Analog TV), you can have a totally scratched up record (fuzzy picture), it might squeal like crazy (banding/CCI), but you’ll still be able to hear what’s left of whatever was on it (weaker DX).
I have a similar situation here with New York City. The ESB is 90 miles away, using a yagi antenna I can hear FM fine… even using something as small as rabbit ears. DTV on the other hand, same location, yet it’s trop only. And rare trop at that.

As for improving your antenna situation, it depends on what you want to receive. If you want to catch E-Skip there really isn’t a clear answer because of the varying signal levels that come in. In strong E-Skip (as Saul did) it’s possible to use even simple rabbit ears to log something. While weaker E-Skip will require a larger, more elaborate antenna. As for trop… personally I have received trop DTV on rabbit ears from Norfolk, VA and northeast NC from 200-250 miles away. Your mileage will vary there though, because trop does tend to get very intense along the coast here, something that as far as I know does not out west. That said, to get in on any UHF trop you don’t necessarily need anything “huge” (in terms of a giant VHF antenna), especially being UHF. I know some who have had luck with various bowtie antennas, 8, and even 16 bay. If you’re technical enough and want to save money, you can even build yourself. There are instructions all over the internet on how to build one. As for other modes like meteor scatter, or even AU (which I don't think has even been done on DTV yet?), you need a high gain antenna- even on FM.

[SlcDX]

Thanks for the suggestions guys. I guess it points to the fact that I still need a separate antenna for TV if I am going to get DTV DX in the summer. I'm thinking I will see how things are financially in about April and then I will probably invest in a better antenna for TV. I also might be in a different location by that point so the possibilities might be different.

[spunker88]

I can't afford a huge antenna though, the best I can make do with is my cheap one for now until my financial situation improves. The FM-6 actually works fairly well as a TV antenna (for locals anyway) as far as I know, but I won't know until this summer if it really can pull them in.

There are tutorials on youtube on how to build a UHF antenna from wire and coat hangers. Its very cheap to do and will work just about as good as an expensive antenna. Afterall, an antenna is just metal at the right size and distance to receive a wavelength.

Its the other equipment that people use like preamps, etc that get expensive.