TV DXing ain't easy anymore


I've always been an FM DXer. Well, at least since 1968 or so. But since analog television ended here in the United States a few years back, I've really become interested in seeing what television still exists on channels 2 through 6.


Everyone who gets into this hobby usually starts with a TV antenna and a television. So did I. That combination seemed to work okay until analog transmissions ended in the United States. All of a sudden all of the strong signals were gone. I found out that what I could see was just a fraction of the signal strength of what I was accustomed to. So, I had to make some adjustments and I did make a few. Some of them cost me money. Some were free.


If you're still DXing analog signals with just a television (or maybe a bunch of televisions) and maybe a VCR and nothing else, you are probably happy doing what you are doing. But if you really want the weak signals, you need to do much better than that.


I modified the Sabrent card easily. Could not get JB's mod to work with the PCTVPCI card. Both have the SAA7130 chipset.


First off, buy yourself a cheap analog TV card for your computer. You can find them for $20 or less. Plop it into your computer and connect your coax to it. If you still have an analog LPTV on the air locally, tune it in just to make sure the card is working.




Next, go online and download a program called dScaler. It's free and costs you nothing. The link is here. Here is why you should use it.


Video coming out of a TV card is probably of less quality than video you can see on your TV. It needs help, especially for weak signals. dScaler gives you that help. Dscaler takes the video out of your TV card, runs it through through filters (adaptive filtering is the most import one), takes out much of the noise and garbage and lets you either record it or just view it on dScalers own screen. Anything you record will be recorded with the filtering ON. 



This is the dScaler interface. This is where you watch TV, not on your TV Card software. The filtering works on this screen. Can you just do TV Dxing with a TV card? Sure, but just with the strong signals and you don't find many of then anymore, especially in the northern half of North America.


Click here for more information on setting up dScaler for watching and recording your TV DX.


Another thing you can do to help you see those weak DX signals is to find yourself an outboard analog TV tuner. There is just one available and it's in the UK. The link is here. What you are looking for is a TV tuner called the D100 (or the newer D500 which only covers channels 2 through 6.) This will cost you some money, probably around $150 but well worth it, in my opinion.


So, here is how this works. Your antenna coax plugs into the D100/D500. Output from the 100/500 goes into your TV card. Your TV card has to be tuned to UHF (ch31 on mine, not the normal ch3/ch4 a DTV box uses). Then you dial in the channel using the large calibrated knob on the right.

    What happens is that the Dxxx sends a signal with a narrow bandwidth to your TV card (or television, if you choose to use it that way). This bandwidth is adjustable using one of the knobs on the left side of the unit (but keep it narrow). You will be able to see very weak signals (S3-4 on an Icom R7000, for example) that you just cannot see using just an antenna and a color TV. When skip is in, you will know about it before anyone else.)


Click here for more information on what the dials on the D100 do and how to set them.


So, let's recap. If you are looking to receive weak signals (and double hop signals are weak) then the minimum you should do is use a television with a D100/500. If you want to go a bit further yet, get a D500, feed that into a TV card, tune channels with the card and watch the video with dScaler on your monitor. That's a step up in the right direction.


Next we have an option for those who want to take it one more step further. When you buy a TV card, buy one that has a Philips SAA7130/7134 for a processor. Usually this is a selling point on the card and is marked on the box (the chips on the board are marked also). Then download a small program called TV Controller from this website. Look for the following symbol for download.


If you have downloaded this correctly, you will be able to then throw your TV Card into "Free-Run" mode which disables your horizontal and vertical sync and leaves a picture "floating" on your screen. A small 10pf trimmer capacitor can then be soldered on your TV card between GND and the crystal to stop any motion to let you view an extremely weak picture. This method is used by top TV Dxers in Europe to watch distant TV DX when other methods fail. Read up on the material at JB's website for more detailed instructions and information.


A scanner can really be a valuable resource, if you haven't already got one. You need a scanner that will let you program in analog TV video frequencies. Enter 55.240, 55,250 and 55.260 for ch2. Enter 61.240, 61.250 and 61.260 for ch3. Enter 67.240, 67.250 and 67.260 for ch4. Enter 71.240, 71.250 and 71.260 for ch5. Hook up the antenna to your scanner and turn it on and let it scan. Since scanners are extremely sensitive radios, you will begin to notice weak E-skip when your scanner stops on a given frequency. By the way, of the three video frequencies per channel, the lower is called minus, the center is called zero and the highest is called plus (-, Z and +). You don't even need to turn on your TV or your card if your scanner shows no activity.


So there you have it. If you live in an area where you still can receive strong single hop TV DX, you may not care about any of this, and that's okay if strong DX and single hop Es is your thing. And it's even more okay if you lack the funds to purchase a piece of gear. It's completely understandable.


But if you're not and you're just afraid to try anything new then you should think about it. If you are out of single hop range for much of your analog TV DX, you really should help yourself.


©2012 M.Bugaj

No reprint without permission