View Full Version : 7 Foot Dish at 108 ft.

Robert Grant
01-20-2008, 04:11 PM
I recently bought a Toshiba MW20H63 set (a 20" CRT TV w/NTSC, ATSC and QAM tuning, a built in DVD player and built-in VCR) as a Christmas gift for a relative.
Not to disappoint the recipient, I checked the set to make sure it worked, and observed it's DTV reception.
The instruction book states one should to an automatic channel scan after attaching an antenna to the set, and then delete any unwanted channels after the scan is completed.
It does not mention any provision for the direct entry of a DTV station by a station's actual RF channel (I might mention here that NO instruction book I have ever read mentions the existance of actual channels, and actual channels seem to be a well-kept secret among non-DXers.)
Attempting to enter an actual channel by number and enter key automatically sets the channel back to the channel one had already been on (much like entering "70" on an analog set would be rejected as a "bad entry")
After considerable experimenting, I found a way one CAN enter actual RF channels on this set:
1) touch the digits of the actual RF channel number you wish to access, for example, (4) (5) for channel 45.
2) touch the (-) key.
3) touch the (1) key.
Now DON'T! hit the ENTER key, just wait. (If you touch the enter key, it will revert to the last channel).
In my case, this brings up WDIV-DT, displays "4-1" on the OSD, and automatically commits WDIV-DT to memory as virtual channel 4.
A logical assumption would by that the same would apply to many Toshiba sets, especially those that use a CRT.
This is actually of importance beyond TV DXing. Without this knowledge, it would have been impossible to have WBGU-DT (actual 56, virtual 27) and WTVS-DT (actual 43, virtual 56) both accessible. The set would not have loaded WBGU into it's memory when aimed at WTVS, and vice versa.
This would even affect those using an indoor antenna for local stations.
Say one could not get WTOL-DT if the antenna is in "just the right spot" for WTVG, and vice versa. Doing a channel scan to catch either station would exclude the other.

Robert Grant, N8NU
Temperance, MI

01-21-2008, 10:56 PM
Did you get a feel for how decent either analog or digital reception capabilities were on the set?

Robert Grant
01-23-2008, 09:18 PM
I did not have time to give it a side-by-side test with anything else I had, or any technical test.
If memory serves me correctly, it did not stand out as being particularly better or worse than my Sylvania 6427GFF (which, in turn, is comparable to the RCA ATSC-11 STB in actual receive performance, though the RCA STB is better at bringing up the call sign when only a PSIP is available).


01-24-2008, 10:33 AM
I have been going into the local Sears late in the evening and doing “rabbit ear” test on various sets. The Toshiba 32” LCD HDTV had good sensitivity compared to many others. It was the only one that picked up a local DTV with the in-store demo RF cable connected, perhaps that particular cable was leaky and/or it was in a good spot(?) The thing that bothered me was it didn’t display the PSIP DTV call letters.

The only brand I’ve found *so far* that has an “add-to digital channels” scan that doesn’t delete the previously stored channels are the Sony sets. But with that same rabbit ear test using a local analog UHF station they had poor sensitivity, this proved true on more than one Sony in various locations in the display area. I would like this weak sensitivity finding be proven wrong because functionally the Sony’s are DX friendly. BTW the Sony's display the call letters, unlike the Toshiba & Sharp sets I've tried out.

Robert Grant
01-26-2008, 05:03 PM
My Sylvania 6427GFF 27" CRT TV with SDTV tuner (made by Funai) has direct entry by actual RF channel, and allows the addition of channels to the memory after an automatic scan has been completed.
Unlike the RCA ATSC-11 STB, the addition of a channel to memory is not automatic, that is, for example: entering "58" when a viable signal from WJBK-DT is present will case the set to show WJBK-DT, and the OSD channel display will briefly show "D 2-01" in magenta text.
If one does not go the menu->DTV channel set->ADD to add the station to memory, the link between RF channel 58 and virtual channel 2 will not stay - if one were to turn the set off (and on again), change tuning mode to analog (and back again), of change channels (and hit channel return again), the OSD will display "D 2-01" in magenta, it will try to tune an ATSC signal on channel 2, and no program will be seen (unless, very unlikely, WKYC-DT or KOTA-DT happens to have a viable signal at the time!)
Adding a channel to memory will change the color of the OSD channel display to cyan, and pressing "2" will bring up WJBK-DT (58) every time (but a channel can also be deleted from memory easily, and WJBK usually is all summer :-).
I think you're right about the Toshiba display not showing the PSIP call letters, and yes, this actually is a significant drawback (I had dismissed this, as I thought it was a lack of PSIP on my relative's CATV system).
FWIW, PSIP does not always show call letters. WMAQ-DT, for example, was simply seen as "NBC5".

We really shoud be studying this matter further, making up a scheme to classify the features of a DTV device's tuning options, and gradually putting together a database of which sets feature which features.

Last, my Sylvania was purchased in December, 2005. I don't know if current sets have this flexibility. Many sets sold as ILO seemed to have the same tuning menu.

73 de N8NU

01-27-2008, 01:35 AM
As you both know, many DTVs these days are putting names like "ABC26" into the PSIP data rather than using calls; but it sounds like both of you have come up with something that is being done by the TV. I wonder if that will be common in the future. I also wonder how the PSIP ID data will be displayed on those government-approved soon-to-be-available DTV converters.

01-27-2008, 03:42 PM
Thanks Robert for the Sylvania notes, I think Sears here has current models; I'll try one or two out. And yes to the feature database idea!!

I've been in the process of programming a new Samsung (2353H) and it's very difficult because new scans are destructive, and once an analog channel number is programmed in a given channel number you can't get a new digital on that channel without doing a scan. Fortunately, the destructive scan starts on whatever channel you are on and you can quickly hit stop, but it's hard to not run over to the next RF channel and delete a programmed virtual DTV channel residing there. Another problem is that %^$# "LNA" that becomes active when you do a scan, it overloads frequently and does no good on a weak channel. Once a channel is added you can turn it off which I make a point to do for all channels.

What I've been doing is attempting to get a DTV station programmed in for every RF channel and have all but a few. It will only hold one virtual number at a time for each RF channel. So, you can control RF channel selection by selecting the currently programmed virtual channel number. I made a spreadsheet and entered all the received stations as I get them and can sort the columns to find the desired RF channel.

One example of operation is there are three RF=ch32 DTV stations in this area (Shreveport “6” /Little Rock “4” / Alexandria “31”) I can tune to whichever station/virtual channel is actively displayed and the set will dynamically change (and go to) the newly received station’s PSIP call letters and virtual channel(s) as I move the antenna rotor.

I like the set in many ways, good sensitivity & dual RF inputs, of course one is cable format only, but it works for the analog VHFs. From what I've seen just looking at the menus in the store all current Samsungs are this way, sad because they are good sets. I may see if I can get through to someone there and tell them their competition Sony has an “add digital channel scan” and see if that motivates them to change.

Yes, the PSIP data really varies. The state PubTV network here in Louisiana I work for insists that we display "LPB" instead of the each transmitter/station’s call letters, Mississippi & Arkansas PubTV use the call letters.

I dug and asked around to see if there was an FCC rule that stations enter their call letters in the PSIP for display, so far it seems not, so it's like the wild west, and sometimes just on the whim or the station engineer or programming dept as to what they enter/display. It was decided up front to limit them to 7 characters because of character space limitations within on-screen program guides.

01-27-2008, 10:55 PM
Channel Master Parabolic at 108 feet????? Goodness, please post some pictures! When I had that antenna back in the 70s, it caught so much wind it kept bending any mast I attached it to, even plumbing pipe.

01-28-2008, 07:46 PM
That happened to me too in the 70’s back when I first had this antenna up :-(
I had a CM Crossfire VHF on the bottom, the CM 7’ UHF in the middle and a CM Probe 9 on the top, it was a beauty. I got up after a storm one morning and found it bent over, fortunately the Crossfire hit the tower and braced it enough to keep it from tumbling down. That was using a standard 10’ and 5’ antenna pole put together to get enough length. I should have reinforced it with something inside it.

This time I used fence pipe, the length was good and the gauge is better than store-bought antenna poles. I had to ream out the neck in the top of the Rohn Tower for it to fit. Glad I still had that CM Parabolic in storage; the rotor is a CDE I bought back in the late 70s around the same time as the antenna and my first Rohn 20G sections that were only $35ea.

I’ve attached a couple of photos, sorry I didn't flip them over.

Wish I lived west of here up in the hills, we have a river here and the side I live on is flat and around 80'ASL, but on the other side it gets up to 200-300'ASL.

01-28-2008, 07:52 PM
ps, I'd like to put some wire on the back of that monster like some of you have done to increase the not-so-good F/B ratio, but afraid of it increasing the wind resistance to a dangerous amount for this tower.

I’ve spent a lot of time rotating 180 degrees to see if I’m being fooled by something from the rear, and often it was. It’s a tradeoff I guess.

01-28-2008, 11:53 PM
Most impressive! I had a CM 3617 VHF Crossfire with a Probe 9 above it on approximately 45 feet of Rohn 25, and the CM parabolic was mounted on approximately 30 feet of Rohn 25 - when it would stay mounted. But I'll say one thing - it was a "signal pulling in" antenna! Truthfully, so was the 3617. Wish I still had those two - although I doubt my neighbors share my wishes, even if I am in a "country" subdivision. And I wish I had one of those towers, too. Ah, to long for the days before antennas were considered an "eyesore" by the uninformed public...

01-31-2008, 11:36 PM
Sounds like you have a similar antenna history, too bad you got rid of them, I was lucky and had some storage space at work and kept the UHF parabolic, but sold two different CM VHFs I had to a friend who lives in the country, he may still have one of them up, I’ll have to ask...

Too bad you can’t get the antennas you have now up higher, I had complaints from neighbors after putting mine up but they’ve now accepted it. We had a crazy windstorm a couple of days ago and it held up well, it seems the wind resistance is not really that bad.

I was curious about your Alliance Rotor and found this: http://www.rotorservice.com/press3-alliance.htm I almost sent a rotor to these guys but ended up cleaning it up myself.

Are you familiar with DVB Satellite? It can be done with a reasonable small KU dish and there’s a lot of international TV & Radio up there. I purchased one just before the Iraq war began in ’03 and was able to see Iraqi TV going on and off the air. I don’t have a blind-search receiver yet so I have to look up the frequency info and enter it before scanning. Receiver and dish packages are really inexpensive as they are mass produced for use in many countries where these are popular.

A lot of what’s available are foreign TV broadcasters, but there’s a good bit of English language programming up there too. On the weekend the non-english music programs are cool, a universal language I guess you could say. On the news in English there is Russia Today, Al Jazeera, & PressTV. Here’s a good site on “free-to-air” DVB: http://www.ftalist.com/

02-01-2008, 11:28 PM
I put up the 3617 VHF and Probe 9 up when I graduated from high school in 1976, and they were still on the tower at my parent's house when we were selling the house two years ago. The realtor said he had someone to safely remove the tower and the antennas (the tower had gotten quite rusty and didn't look safe to climb but I wanted those antennas). Well, those bozos cut the tower down and needlessly crumpled the antennas into the dumpster we had onsite. I really think the antennas made it down in decent shape, but those guys just trashed them. GRRR! I really wanted those antennas, even though the 3617 might have been too much to put up at my current house and still keep neighborly peace. Interestingly the rotors I used back then were good ole Radio Shack models, and those things never hiccuped at all turning ANY antenna, including the 3617/Probe 9.

The reason I bought the Alliance rotor (from Norm's 3 years ago) was my recent luck with newer Radio Shack models was poor. So, I decided I would buy a ham rotor even though all I was turning was two TV antennas. It's certainly been able to handle them with no problem.

I've heard of DVB from a fella that was selling receivers, but I didn't take the time to research. Maybe I thought satellite reception isn't out of the ordinary like DXing???

02-02-2008, 11:11 AM
Antennanut wrote:

The reason I bought the Alliance rotor (from Norm's 3 years ago) was my recent luck with newer Radio Shack models was poor. So, I decided I would buy a ham rotor even though all I was turning was two TV antennas. It's certainly been able to handle them with no problem.

Rotor quality has gone down the sewer the past few years. I got burned with RS rotors and even C.M. three wire rotors, so two years ago I looked at ham rotors and ended up buying an Alliance HD-73 (N.I.B.) from Rich Wertman. Sure it cost more than a cheap rotor but hopefully it will last more than a couple of years.

02-04-2008, 11:54 PM
[/I]Rotor quality has gone down the sewer the past few years.

I have a bunch of RS control boxes if anyone wants 'em!! That assumes they are working any better than the motors...

Robert Grant
02-10-2008, 03:00 PM
whole replay was unnecessary, this was a response to what apparently is a server glitch

08-08-2016, 10:40 PM

I am curious if you still have your parabolic in the air.

I am in Toledo and thinking about commissioning the 4251 soon.

08-10-2016, 02:17 PM
Rotor quality has gone down the sewer the past few years. I got burned with RS rotors and even C.M. three wire rotors, so two years ago I looked at ham rotors and ended up buying an Alliance HD-73 (N.I.B.) from Rich Wertman. Sure it cost more than a cheap rotor but hopefully it will last more than a couple of years.

Wow! I wrote that back in 2008 when I had that rotor for 2 years already. So I put if up in 2006 it's 10 years old now. It's now 2016 and that HD73 just keeps chugging along with my VHF antenna and XG91 on top of it. I imagine I can get at least another ten years out of it. Hell, it may just outlast ME!

09-01-2016, 05:34 PM
This installation of a CM parabolic dish at 108 feet is a great accomplishment! Yes, indeed, please post some photos!

Dave Sinclair
Vancouver, B.C.