[opendtv] Re: Zenith box at Radio Shack
- From: Richard Hollandsworth <holl_ands@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 28 Feb 2008 12:24:19 -0800 (PST)
Since no one has figured out what is inside Digital Stream SD-STB,
why not take a look inside and post numbers for
tin can tuner and big chips both here and on avsforum's
CECB SD-STB COMPARISON thread....
BTW: Zenith/Insignia tin can tuner designs seem to be typical
single conversion superhets with only one varactor input bandpass filter:
https://fjallfoss.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=406918&fcc_id=\\\'BEJ9QKE00710\\\
[LG and Sanyo tuners may be a guaranteed dual source situation...]
The double conversion MicroTune MT2131 chip is reportedly
used in the Sansonic FT300A and FT300RT CECB SD-STBs
with the 6th Gen Auvitek AU8515 ATSC Decoder/Display chip:
http://phx.corporate-ir.net/phoenix.zhtml?c=121862&p=irol-newsArticle&ID=1090989&highlight
http://www.microtune.com/products/pdf/mt2131_11.pdf
PS: MT2131 also used in TiVo HD-DVR, LG DVR Recorder, et. al.
If they eliminate the varactor input bandpass filter (as shown in
some app notes), the input mixer may be more prone to
out-of-band overload desensitization:
http://rfdesign.com/images/archive/0601Norsworthy67.pdf
When Sansonic boxes become available (still looking...) we'll
have a chance to see if double conversion helps...or hurts....
holl_ands
==================================
Cliff Benham <flyback1@xxxxxxxxxxx> wrote: Manfredi, Albert E wrote:
>>
>> It would indeed be ironic if the DTV convertor boxes perform
>> better than integrated TVs.
>
> I don't think they do. Cliff says that his new Radio Shack box performs
> the same as the Philips DVDR3575H/37. If that's the case, then it also
> performs like new LG TVs. At first, I thought the Philips was slightly
> better, maybe, but in more recent comparisons, they both did the same
> with marginal stations. Hard to say which is better.
>
> Even if they did perform better, the only logical next step would be for
> TV manufacturers to use those good and cheap front ends on their updated
> products. (After re-enabling the NTSC tuner.)
There are three STBs connected to the roof top antenna using RG-11 all
the way.
The first box is in the basement, a Samsung DTB-H260F. The second and
third boxes are upstairs in the living room by the 38 inch TV, at least
35 feet of coax distant from the Samsung.
The second box is a Philips DVDR3575H/37 DVD Rec/Rcvr and the third is
the newly acquired Digital Stream DTX9900 which outputs 480i only.
Reception on the Samsung is much better than any previous STB I've tried
over the years, but now the Philips beats it easily and I now think the
Digital stream STB is a little better than the Philips. All this
considering that the Samsung is getting the antenna signal directly, the
Philips second and the Digital Stream last.
The Samsung and the Philips both have RF through-puts and I'm using
those to feed the antenna signal to all three boxes.
The interesting thing I have discovred over the last week is that I now
*believe* overall reception through the Digital Stream box is slightly
better than the Philips. This is based on checking reception of all the
channels at various times of day and night and during varying weather
conditions.
The Samsung never found two of the channels that both the Philips and
the Digital Stream found when they were first setup.
The Digital Stream STB has better reception of the two weaker channels
than the Philips.
So after a week of playing, I think the Digital Stream STB performs the
best of the three.
Cliff
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