DigitalStream DTX9950 - Page 3

The FCC site will also list the RF frequency if you enter the station's call letters.
http://www.fcc.gov/fcc-bin/audio/tvq.html
Many of these will be changing frequencies in Feb. also.

At the FCC site posted above, you can also just enter the City's name in the "City" field to search for all TV stations in a particular town.

However, that listing is according to the site of the license, not the location of the transmitter.

Several Chicago stations are licensed to other nearby cities, and a search of that site for Chicago, Illinois, will not turn them up.  They're there under the cities of their licenses (Aurora, Gary, Hammond, or Joliet).

True. Good point.

I am amazed at the time and energy that the members of this blog have spent on such a trivial matter! Hey, with the government discount of $40, this a/d converter box only costs $20 plus tax - it's not like you were spending thousands of dollars on a new car that you were planning to drive for five years. Get a life! There are so many factors in signal strength that it's not worth quibbling about - the converter box, the antenna, the position/height of the antenna. the distance to the transmitter, the terrain (ghosts, etc.), ad infinitum.

I purchased a DTX9950 (at Radio Shack) and using common sense, attached it to my TV, replacing the use of the Cox Cable with OTA via the DTX9950. I used a Phillips MANT410 amplified indoor rabbit ears/UHF loop set-top antenna. I have a line of sight access to Mt. Wilson on which are located 90+ per cent of the Los Angeles/Orange County TV station transmitters, approximately 40+ miles away. The antenna was sitting a TV set height above ground.

I made all the connections necessary, turned the converter on, and went thru the scanning process, where it picked up every digital signal channel/sub-channel among the LA/Orange County stations (total approx 40), missing those stations located in neighboring San Bernandino and Ventura Counties. I feel positive that if I had a roof-top rotatable antenna, I would have gotten more, perhaps even as far away as San Diego.

I then ripped thru all of channels/sub-channels - no video or audio problems were encountered. I then pushed the A/D button, and punched in the actual VHF/UHF broadcast stations in order to observe the analog signal reception. Due to the limitations of the VHF portion of the indoor antenna, the analog signals from the lower freqs were not good, however the UHF stations came in fine. That was my experience with the pass-thru - I have no complaints.

For $20, this unit is a real bargain. It does its job well.

Now for those of you who are knowledge-challenged about digital TV, let me throw in a few facts:

(1) In some cities, TV stations that are currently broadcasting their analog signals on UHF channels have in many cases been assigned VHF frequencies to use for their simulcasted digital signals. (Fresno, CA for example - all analog stations there are UHF, so for those who are contributing their experience to this blog, please identify your geography.) Receiving digital signals at lower VHF signals involves other factors than UHF signals. So, my experiences with an indoor antenna receiving UHF signals would not be relevant for a Fresno resident - they're trying to capture VHF signals!

(2) Come Feb 2009, MOST US TV stations will abandon their temporarily assigned alternate frequencies and start broadcasting a digital signal on their currently assigned analog frequency. However, those stations currently assigned to channels 52-69, will be assigned new transmission frequencies as this portion of the broadcast spectrum will be abandoned by the FCC to other than TV usage. Any station currently using these frequencies for TV will move, whether they are broadcasting a digital or analog signal on that freq. They may or may publish their move, since with the NTSC tuners, the viewer really isn't aware that their TV is tuned to channel 31 when the screen says 5, for example. The point is, just because my DTX9950 works today very well with a small indoor UHF loop doesn't mean anything regarding this configuration after Feb 2009. Here in the LA area, the "big"/network stations are all VHF, and use 2,4,5,7,9,11,13, all of which are not received well with my "rabbit ears" - I will have go shift to a better VHF antenna, probably an attic-mount or roof-top.

(3) Low-power stations (there are 3 in LA) are NOT required to cease their analog broadcast in Feb 2009, so the analog-pass-thru feature is valuable here for those who desire to watch them.

(4) The analog-pass-thru feature will also be VERY important for the millions of US TV viewers who live in San Diego, Detroit, Buffalo, El Paso, and other US cities located along borders with Mexico and Canada. Those two countries have completely different plans regarding the shift to digital TV signals. Canada has a date, I believe two years after the US, and in Mexico, the shift to digital is on a station-by-station basis. Some stations, for example, in Tijuana (just across from San Diego) already are simulcasting and will follow their US counterparts. Actually at least one of the "network" channels serving San Diego is physically located south of the border ( a Mexican licensee) and will definitely be shifting in Feb 2009.

Bottom line, for the price of 4 super lattees at your local Starbucks, this box does the job very well. And your experience with it today may change dramatically come Feb 2009, so be prepared.

Dude, I did not read your first post bloggie past the initial paragraph but you are telling US to get a life ?

We only get TWO coupons and many here have been screwed out of one or both thanks to the NTIA. Additional converters will cost us full price. Careful selection IS important.

Not to mention that many here are relied upon by family and friends to provide expert advice.

No, not "most."  Some, but not most.  You're assuming parochially that the rest of the country is a clone of your home town.

Most will keep their current digital channel assignments and stay where they are.  Some will move their digital signals to their legacy analog channels; some (mostly those that were assigned digital channels 52 or higher) will move them to channels that are neither the station's legacy analog channel nor its temporary digital channel.

And I'm with Gerhard911 on the other matter.  Anyone who can post something that long is in no position to deride others for their interest in this topic.

I find that my DTX9950 has to be on a channel for a few minutes before it will download the PSIP synopses of the current and upcoming programs.  This isn't a case where the channel doesn't provide them; then they'd not come in at all.  Rather, the channel (this happens on several channels, in fact) does send them, and my Magnavox TB-100MG9 and my TV with a digital tuner can display them within seconds after being tuned to the channel, but the DTX9950 will show the program title and times but "No information acquired" for the synopsis until it's been on that channel for several minutes.

Is my unit messed up or do everyone else's DTX9950s act that way?

Ah HAAA, the Lurkers and Trolls have landed.

No, it's not brain surgery, but fun anyway... Thanks everyone who placed their 2 cents and, some spent more, 3 cents worth of knowledge... and Thanks Hankjeff for adding to our knowledge base.

Dennis

Indeed on time spent
A quick glance at your post
seems to be about a thousand
words.. Good work Troll.. Haha.


John

This is true. All the stations in my area (SW-FL) will be remaining on their new digital channels. They have put up expensive new antennas in some cases whole new towers and are not going to abandon them. And nationwide very few low-band (ch 2-6) VHF stations will return to their old channels because low VHF chs are considered ill-suited for digital transmission.

And drive-by trolls. The worst

None of my main DMA market stations are changing frequencies on 2/17/09.

All of my frequencies in my market are remaining on their pre
transition frequency.. well actually one is "flash cutting" to
their original analog frequency Channel 34 Binghamton DMA.


John

I have been doing more comparisons between my DTX9950 and my LG tuner equipped Zenith DTT900.

I live in the northern suburbs of Cincinnati,OH and have always had excellent reception of the Cincy stations but could never pull Dayton stations in with decent analog reception. This in spite of using a roof mounted CM3020 fringe rated antenna with rotator.

So I decided to give the Dayton digitals a shot. I added a CM7777 preamp and replaced some old RG58 & RG59 cabling with RG6. Turning the antenna toward the Dayton transmitters I can now successfully pull in most of the digital stations plus all of my previous Cincy market channels.

This has uncovered an apparent weakness with the Zenith's LG tuner. It had already been reported that the LG was less sensitive than the Sanyo tuner used in early DTT900s. It also appears to be inferior to the Thomson used in the DTX9950.

The DTX can successfully tune the NBC affiliate from Dayton and shows signal strength @ 70%. The DTT cannot pull that station in and checking it's RF frequency with the signal strength tool shows @30%. Also, the Kentucky PBS affiliate suffers from macroblocking, dropouts and freeze ups on the Zenith that do not occur with the DTX9950.

I see a lot of talk here comparing signal readings of different boxes- this one get 40% signal- versus that one gets 70% or whatever. You should realized these are purely arbitrary figures produced in the converter only to give relative readings when comparing or aiming antennas. These readings tell you nothing about the actual sensitivity of the converter. For that you would need to measure the microvolt input to antenna connector of each converter thats required to produce a stable decode. This is generally done using calibrated signal generator.

I realize that. I only indicated what the converters each showed for comparison purposes. The DTX9950 had sufficient signal at an indicated 70% whereas the DTT900 did not at an indicated 30%. It should have been obvious that each box was receiving the exact same signal from my antenna feed.


Or observe if a channel can be properly tuned.


Thanks for that helpful tip

I just bought one today & was wondering about the heat issue. Is it really a problem? If so, is there room to strap a heat sink on the tuner? I was also thinking about drilling bigger ventilation holes in the lid. I looks as if it snaps off with a flat screwdriver on those 4 tabs...is that correct? Thanx for your review!

I was also thinking of putting a heat sink on the tuner, or heat source but I'm not sure what is causing all the heat. Is the tuner or the
LGDT1111D chip that is causing all the trouble? I still don't have mine yet.

I think the bigger holes and heat sink would help a lot as would placing something under the unit to lift if off of the surface it is setting on. This would help with air circulation under the unit.

Dennis

Okay, got my DTX9950 & modded it for better heat dissipation. Taking it apart is EZ, remove 2 screws, 1 on bottom & the other 1 is on the back. Then gently insert a small flat screwdriver in each of the 4 slots on the 2 sides. There's 4 plastic tabs that need to be pushed inward slightly while pulling the cover off. Disassembling the unit is fairly straight forward once the top cover is removed. Check my next post for link to mod fotos.

Okay, guess I can post URLs now.

http://picasaweb.google.com/willace1...ey=3sDQFnYO-Xc

Excellent, have you taken a temp reading after the mod and compared it to the before mod temp? How much did this help with the heat problem?

If one wanted to place a mufffin or pc fan in the unit, where would you hook up the wiring, or would you recommend doing this? Could you use the 3.3v thingy that KLM-TECH mentioned in his post to do this? Check out the photos on his post...

http://www.klm-tech.com/9950/index.html

Thanks for the info.
Dennis

After reading a number of DTX9950 reviews it was clear DS underestimated ventilation, mainly around the tuner box(power supply is inside the box too). So I just modded it before I hooked it up & will have no way to compare before/after. I'll report back here after I start to use it, I'm still looking over the manual.

If the heat is still a problem I may use a PC mainboard chipset cooling fan(12vdc). If I tap the 5.3vdc, it will run slower, but should work okay. Tho, I expect I could live with it heating up a bit before I would add a fan.

I was considering a DS as a possible second box option but the heat issue is a deal-killer. Bummer . . .

(Just a thought ) Depending on your point of view, adding a heat sink from a chipset mother board might make things worse.

What ever is generating the heat inside the tuner can may not be bonded to the shield. It just gets hot and radiates the heat to the shield. If they are like any other TV tuner, this is probably the case.

Putting something on top of the tuner can (heat sink in this case) could make things hotter inside the tuner because the surface of the tuner can is not totally smooth and neither is the heat sink surface. At the very least, need to have a thin layer of thermal grease to -help- make up for the small gaps/in between the two surfaces.

OK, so now the heat dissipation area is greater with added heat sink. This just means it will take things a little longer to heat up. Need to have some forced air flowing over it still. Drilling holes helps more but If I wrap the box up in a plastic bag for example, all the holes in the world won't help. Need to get cooler outside air in.

As for the heat of the 9950 in general. For those concerned, which includes myself, as I very much hate heat too, wait before purchasing your box if you can and see if there are any over heating reports. As a bonus, it will give the rest of us time to see if it has any audio issues.

Remember, the consumer seems to be the product research/testing department these days.

(Maybe some one some day will pull the tuner can apart and see what's inside heating up.)

- -
As for the post wondering if we are talking doubt heat on the LG chip or tuner- We are concerned about the heat from the tuner itself and not the LG chip.
- -
On another subject, I have a note here to watch the NBC nightly news this coming Tuesday and I will hear how the DTX9950 does sound issue wise.

Gook luck to all on your experiments!

John

I have a Zenith (April 2008) DTT900. It has a metal case that is well ventilated, implying excellent thermal design.
Yesterday I was testing it and it was powered up for six hours. This is the longest period I have had the Zenith DTT900 powered up. It was just a little warm. I think this confirms a good thermal design.

I specifically avoided the DigitalStream DTX9950 to wait for the Zenith DTT901 to arrive at my local Radio Shack partly because the Zenith DTT901 has the lowest power requirement of any Energy Star listed CECB, making it the coolest box available. Thomson tuner boxes have a history of running too hot. Note that future versions of the DigitalStream DTX9950 for release in August will have a lower power requirement, still not as low as the 3.9W Zenith DTT901. Also with regard to signal reception, per the Zenith DTT901 thread, the reception of the DTT901 is superior to the DTT900. So comparing the DTX9950 to the DTT900 is invalid, and it must be compared to a Zenith DTT901 when making decisions about which has better reception.

Power Consumption Data:
http://www.energystar.gov/ia/product..._prod_list.pdf

Zenith DTT901 to DTT900 Reception Comparison:
http://www.avsforum.com/avs-vb/showt...9#post14083089

Setup my DTX9950, ran it for over 6 hours...case felt slightly warm to the touch, but not excessively so. In the back where my RF cables attach was warm to the touch, I pinched the metal connector of one of these cables hard & held my fingers there for some time. Twas warm to the touch, but I would not call it hot & by no means did it cause any discomfort to my fingers. IMO there's no heat problem with this particular unit! Since I modded it before turning it on, I cannot really compare it before & after, tho it was certainly an easy modification.

I'm using it with my PC which has an analog TV tuner, 5.1 audio & a 23" LCD monitor. The picture quality was considerably better after conversion, the audio was about the same quality. I live in a large urban area & have a rooftop antenna(w/rotor). Setup was simple & remote was easy to use. IMO it was $25 well spent & I'm quite happy with my DTX9950...a keeper!