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post #10141 of 10423
Quote:
Originally Posted by Calaveras View Post

The last few days of near constant rain has provided a very good time to check your reception under nominal conditions. With stable temperatures and no inversions signals should have been stable for days.

My temperature since mid Saturday has been 50F +/- 1 degree. I don't think I've ever seen such a small variation over almost 2 days. Signals have also been remarkably stable. I carefully monitored Sutro, Fremont and Salinas signals, especially UHF on the higher antennas. I can positively say that rain has no affect on the signals at all.

Chuck

I, too, noted the stable temperature. I thought my thermometer was stuck, since it sat at 57 degrees night and day, but this morning it had dropped down to 53.

Signals were very steady here this past weekend, too, but I sure didn't get the great signals that you did. Some of your signals from Sutro are quite impressive! If anything, mine were below what I consider "normal". Only 31 and 58 were coming in from Walnut Grove. 3, 6, 10, and 13 were all below the cliff edge at about 13.5 dB SNR. KAXT 1 was hovering around the cliff edge at 16 dB. Signals from the other South Bay stations 14, 36, 48 and 54, 42 and 52 from Mt. Diablo and the three stations from up north, 22, 50 and 68, were all about a dB or two lower than normal. If these are the signals I get under nominal conditions, I must be experiencing the affect of inversion quite a bit of the time here, since the signals are usually higher.

Larry
SF
post #10142 of 10423
Quote:
Originally Posted by Calaveras View Post

I've seen the following SNRs since Saturday: Sutro - KPIX 17 dB +1/-2 (some dropouts), KQED 23 dB +/-1, KMTP 21 dB +/- 1, KRON 17 dB +/- 1, KCNS 16 dB +/- 1 (lots of dropouts - interference from KMMD), KTVU 16 dB +/- 1 (lots of dropouts), KBCW 26 dB +/-1 (amazing signal).
Chuck

I was just looking over your signal report from Sutro and noticed something interesting. The three stations on the west antenna, 2, 4, and 5, were all 16-17 dB, while the ones on the north antenna were 21-23 dB with the exception of KCNS where you have interference. 44 transmits from it's own separate antenna on the southeast tower below KGO's. Could antenna placement make that much difference?

Larry
post #10143 of 10423
Quote:
Originally Posted by dmfdmf View Post

I thought this was a folded dipole too but I think it is something else. Here is a description...

The branches of the T are 31" long for a total length of the 62" across the top. There is no balun. So my question is what kind of antenna is this and what frequency would it be optimal for?

That is correct... it is a half-wave folded FM dipole....should be 55" to 67" long, and you indicate 62" ............... optimal for? ......90.5 FM
My antenna building book says make it around 5 feet (60 inches) for FM
The calculations are something like this...............
For 99 MHz .......4'-8 23/32"
For 100Mhz ......4'-8 5/32"
For 101 Mhz......4'- 7 19/32"
For 102 Mhz......4'- 7 1/16"
.......and so on.

Now .... back to the tv channels (RF) real channels
Half-wave folded dipole..... for tv

For Channel 2 ..........8'-2 17/32"
For FM band .............5'
For Channel 7 ...........2'-7 23/32"
For Channel 12..........2'-4 1/2"
For Channel 51 ........0'..8 3/32"
Edited by 888CALLFCC - 2/11/14 at 1:54am
post #10144 of 10423
Quote:
Originally Posted by Larry Kenney View Post

I was just looking over your signal report from Sutro and noticed something interesting. The three stations on the west antenna, 2, 4, and 5, were all 16-17 dB, while the ones on the north antenna were 21-23 dB with the exception of KCNS where you have interference. 44 transmits from it's own separate antenna on the southeast tower below KGO's. Could antenna placement make that much difference?

Larry

Apparently it does or it has something to do with the characteristics of that antenna. Maybe there's less RF getting up to the top of Mt. Diablo which it has to refract over. KCNS is actually the strongest of the three stations on that antenna but KMMD is stronger still.

It didn't take long for the inversions to return. The valley is fogged in and it's sunny up here. No Sutro this morning except for KGO and KBCW but KKPX is in. Salinas is strong. KEMO is SNR 31 dB.

Chuck
post #10145 of 10423

Hi,

 

It looks like the single wire branch FM antenna has an impedance of ~ 75 ohms so the F - Connector is the correct one.

 

Plain Wire, Fancy Reception

http://home.earthlink.net/~schultdw/antenna/PlainWireFancyReception.html

 

Suggests an improvement for FM.

 

SHF

 

I also find lots of construction details for making a FM antenna using 300 ohm twin lead but little on the theory.


Edited by SFischer1 - 2/11/14 at 5:52pm
post #10146 of 10423

@SHF_

 

Good find on that link. So it sounds like the FM antenna I found is a half-wave, dipole at 62" across, tuned for 90.5 MHz as 888CALLFCC stated (there is an equation on Wikipedia).  Its interesting to me that the impedance is 75 ohms unlike the 300 ohm folded dipole which is more common.  So this antenna is perfect for my FM radio once I get my TV antenna fixed.  I trim the T elements from 31" down to 26 7/8 to optimize for 104.5 MHz (happens to be KFOG). Most of the stations I listen to are at the high end of the dial 101.3, 104.5, 105.3, 107.7 have a lot of static with an indoor antenna. I have a spare coax cable that runs behind my receiver and this antenna already has the F-Connector so all I need is a balun for input to the receiver.   I am looking forward to a sunny day so I can fix my TV antenna and test out this new FM antenna.

post #10147 of 10423

@888CALLFCC

 

That FM T antenna is a half-wave dipole (not folded), but I think the equations are the same to calculate optimal frequency at 90.5 MHz as you say.  I found a formula on Wikipedia and figure I'll need to trim the T elements down to 26 7/8ths inches per branch (4' - 5 3/4" on your table) to optimize for 104.5 MHz (higher up the FM scale). See my reply to SHF.

post #10148 of 10423
Quote:
Originally Posted by Larry Kenney View Post


Looks like you've got plenty of signal in your area from KNTV 11 and with the alteration to the T antenna you're getting some of the UHF stations, so you don't have signal strength problems. All you need to do is find the best spot for your ANT751 where it will receive KNTV and all the UHF stations. Have someone watch as you move the antenna around. A foot or two left or right, up or down, can make all the difference in the world, so you just have to find that good spot. Good luck.

I wouldn't mess with the antenna by bending the elements. It will throw off the overall impedance of the antenna and will affect the UHF reception as well.

Larry
SF

 

I agree, plenty of signal. However, as I was watching the Olympics last night even with the T antenna doing better I noticed very slight pixilation, almost like silver sparkles that wave across the screen. Its usually from bottom to top and occurring in about 30-40 minute intervals and lasts less than 5 minutes. One time the audio did drop out. The ANT751 was worse, so I think I just need to find a sweet spot on the roof to minimize this flutter which I suspect might be airplanes from SFO. 

 

The VHF elements are hinged so they can fit in the shipping box, so angling them back into a V can be a non-destructive test :-) which is part of the fun.  I am curious to try it and see if it helps, easy enough to put it back if it makes things worse.  Clipping the element is a different matter that I'd really have to think about because there is no going back after that hack.

post #10149 of 10423

Hi,

 

"5/8", this is perhaps not the website I saw it first and was the most compelling, but it has some of the same words.

 

Quote:
For some reason that is beyond my understanding, antennas built to multiples of 5/8th of the wavelength get the strongest signals ...

 

http://www.cyberpoet.net/writes/web/infwiz/spant.html

 

I would use some unused 300 ohm twin lead to try various lengths. Once you cut wire off you cannot add it back.

 

SHF

 

Cyber Poet :cool:  Where is my co-worker (A EE) to help with the name of Cal Ohme. (Really) We programed CDC Cyber Computers. 


Edited by SFischer1 - 2/11/14 at 10:29pm
post #10150 of 10423
Hams frequently use a 5/8th wave vertical on VHF/UHF because it has a small amount of gain over a 1/4 vertical but it has to be matched to 50 ohms. A 5/8th wave dipole fed in the center is not going to perform better than a 1/2 wave dipole because it's not much more wire plus it would have to be matched. A 5/8th wave folded dipole will not be 300 ohms.

From your link:

The lead down wire does act as an antenna, but since it travels vertically, it receives significantly less signal than the antenna loop, which should always be placed horizontally (i.e. - parallel with the ground), preferably as high up as possible. If you really want to insure that the antenna is perfect, make the lead down wire a 5/8ths of a wavelength too...

This is not correct. The transmission line does not act as an antenna. It's a balanced line feeding a balanced antenna. The whole point of using a balun to feed a balanced antenna with coax (unbalanced line) is to keep the line from radiating. No balun is required when feeding a balanced antenna with a balanced line. Same is true for an unbalanced antenna such as a ground plane which can be fed with coax directly. No balun required.

A useful formula for making an FM folded dipole is:

Length in inches = 5540/Frequency

This is about 1.4% shorter than the standard dipole formula but takes into account the length of wire at the ends of the twin lead that counts as part of the total length of the antenna.

Chuck
Edited by Calaveras - 2/13/14 at 8:23am
post #10151 of 10423
Here is a link to a story in "TV Technology" magazine about KRON-4's move to the ABC Broadcast Center where KGO-7 is located. They're going to sell the building they're in now on Van Ness Avenue. Since KGO and KSFO radio have moved out, I guess there's plenty of space available.

http://www.tvtechnology.com/article/media-general-to-relocate-kron-tv/223615

Larry
SF
post #10152 of 10423

Hi,

 

Schedules Direct and Zap2It now have "GetTV" on VC 14.3 RF 51. (And other Tribune Media Services based program listings.)

 

Now starting to check if the listings and on air match. Please report if you see incorrect listings.


First Success, a movie I have never seen before.

Quote:

18:20 - The Notorious Landlady 14-3 KDTVDT3, ends 21:05 Suspense (started 59 minutes ago)

A U.S. diplomat (Jack Lemmon) tries to help his London landlady (Kim Novak) in a mix-up over jewels and her husband's murder.

Rating: 3/4

colour no

producer Fred Kohlmar; Richard Quine

length 123 units: minutes

date 1962

 

"Bounce" is incorrect still on Schedules Direct and Zap2It VC 66.3 RF 34, "GetTV" listings still shown incorrectly.


 

TitanTV does NOT have "GetTV" on VC 14.3 RF 51 but it may have "Bounce" listings on VC 66.3 RF 34.

 

EDIT: I have NOT signed up with TitanTV so MMMV. One report that both are correct.


TVGuide does NOT have "GetTV" on VC 14.3 RF 51 and "Bounce" is incorrect , "GetTV" listings still shown incorrectly.

 

SHF


Edited by SFischer1 - 2/13/14 at 7:21pm
post #10153 of 10423
post #10154 of 10423
Quote:
Originally Posted by SFischer1 View Post

Hi,

Schedules Direct and Zap2It now have "GetTV" on VC 14.3 RF 51. (And other Tribune Media Services based program listings.)

Now starting to check if the listings and on air match. Please report if you see incorrect listings.


First Success, a movie I have never seen before.

"Bounce" is incorrect still on Schedules Direct and Zap2It VC 66.3 RF 34, "GetTV" listings still shown incorrectly.
TitanTV does NOT have "GetTV" on VC 14.3 RF 51 but it may have "Bounce" listings on VC 66.3 RF 34.

EDIT: I have NOT signed up with TitanTV so MMMV. One report that both are correct.
TVGuide does NOT have "GetTV" on VC 14.3 RF 51 and "Bounce" is incorrect , "GetTV" listings still shown incorrectly.

SHF

I see the same. If I use the broadcast EPG data for Bounce, it is correct, but the SchedulesDirect data shows the GetTV listings.

On a side note, just cut the "cord" today with DirecTV so starting tomorrow will be OTA plus on-line streaming. Thanks to various posters on this forum for the information, tips and tricks to get everything set up and working properly.
post #10155 of 10423
Quote:
Originally Posted by 4Crawler View Post

On a side note, just cut the "cord" today with DirecTV so starting tomorrow will be OTA plus on-line streaming.
Excellent!
post #10156 of 10423
Quote:
Originally Posted by WhiteWhiskers View Post

Excellent!

Thanks. Now I get to put up with the barrage of "customer service" calls to find out why I cancelled, how many discounts I could get if I come back, ...

Before I packed up the DirecTV equipment, I stuck it on my power meter. The small STBs use about 10 watts on and 3 watts off and the DVR is pulling about 30 watts on and surprisingly the same when it is "off". That DVR alone is using about 22 KWH/month. Funny thing is if you let the DVR auto-power-off and then turn it on, it says it turned itself off to "save energy". I guess those LEDs on the face plate must burn a whole load of power smile.gif

I recently saw a commercial where Direct was touting their Energy Star equipment:
- http://news.directv.com/2012/03/01/epa-recognizes-directv-with-2012-energy-star-award/

It is that same whole house DVR that I have, Granted, their older models may have used more power, so this new model might be an improvement.

Also checked out the power supply for the dish/LNB and that pulls 10 watts continuous. Adding up all those items totals up about what my main server PC uses, so it'll be pretty much an even trade, power wise.
Edited by 4Crawler - 2/15/14 at 12:40pm
post #10157 of 10423
I once had a Radio Shack stand alone tuner which when I opened up I discovered that "OFF" just shorted all of its outputs to ground.
post #10158 of 10423
Quote:
Originally Posted by 4Crawler View Post

Before I packed up the DirecTV equipment, I stuck it on my power meter. The small STBs use about 10 watts on and 3 watts off and the DVR is pulling about 30 watts on and surprisingly the same when it is "off". That DVR alone is using about 22 KWH/month. .

I believe the most power hungry tv equipment in "off " mode are DVRs and cable tv supplied boxes.
The worst (at my place) is a circa 1996 Mitsubishi 36" CRT Diamond-tron tv

19 watts ... Off
170-210 watts... On
2.1... Amps
Compare to a "Energy Star" Sony 13" Trinitron CRT

0 watts ...Off
36 watts ...On

SD-DTV converter boxes ..... 6 on and 0 off
Edited by 888CALLFCC - 2/18/14 at 2:00am
post #10159 of 10423
Quote:
Originally Posted by Larry Kenney View Post

Larry

New channel ?....... 38-6 ...... Works here...... (Boring bay slideshow) ?

And ongoing KTNC problems taking over KDTV's channel ....14-1....14-1.....14-2......14-2
....... They should charge rent....eek.gif for using "14"
post #10160 of 10423
I'm using a TiVo Roamio for OTA only and it uses about 14 watts when recording 4 different shows.
post #10161 of 10423
Quote:
Originally Posted by 888CALLFCC View Post

I believe the most power hungry tv equipment in "off " mode are DVRs and cable tv supplied boxes.
The worst (at my place) is a circa 1996 Mitsubishi 36" CRT Diamond-tron tv

19 watts ... Off
170-210 watts... On
2.1... Amps
Compare to a "Energy Star" Sony 13" Trinitron CRT

0 watts ...Off
36 watts ...On

SD-DTV converter boxes ..... 6 on and 0 off

Yes, lots of hidden power use in some of those devices. I was always wondering how the DirecTV whole house DVR "woke up" so fast when I would play back a recorded show off it. Turns out it really was never off or asleep, so did not have to wake up.

I was trying to duplicate that setup with my media server PC, making use of a wake-on-LAN magic packet to wake it up prior to accessing it remotely. That would work, but there is a 10-20 second delay in response as the server wakes up.
post #10162 of 10423
Quote:
Originally Posted by 888CALLFCC View Post

New channel ?....... 38-6 ...... Works here...... (Boring bay slideshow) ?
Last time I tuned through 38.6 they were showing color bars. That's even more boring! smile.gif

Larry
post #10163 of 10423

Update of my post of about a week ago:  Between storms I went on the roof and swapped out the balun with the broken spade connector.  I found a GE balun at Home Depot (RS doesn't carry them any more).  As a test, I tilted the VHF elements back 45 deg. because it was easy to get an equal alignment at that angle.  The math says it should be around 30 deg. to get an apparent length of 14" toward the towers to optimize reception of NBC at 207 MHz.  Everything looked good, got all my channels back and NBC seemed to be pixelation free (I can't rule out placebo effect, of course :-).  I live in a windy area and the wind just fatigued the spade connector to failure, took a year. I assumed that the wire pulled out of the crimp but it was definitely failure due to flexing in the wind.  Since this was an emergency patch job I figured the new balun wasn't going to last in the wind either, so while watching pixelation-free Olympics, I took the old balun and soldered and shrink wrapped a 24" twin-lead extension so I could tie-wrap the balun to the J-pole and it wouldn't be flailing in the wind and stressing the connection wires. 

 

So last Friday I come home looking forward to watching some Olympics and some Burn Notice and when I turn on the TV and I get no UHF stations, none, not a single one. Only RCH7 (KGO/ABC) and RCH12  (KNTV/NBC) which are VHF.  I poke my head up on the roof and the wires are still attached so its not a failure of the connection this time.  Luckily, I had my old balun with the twin-lead extension ready to go and even though it was about to rain I climbed up on the roof and swapped the balun out again. It works great and I think many of the channels are coming in stronger (higher signal quality per the TV tuner) possibly due to the twin-lead extension.

 

So a few questions, if you please...

1) Can a balun fail in a such way to only pass VHF?

2) Is it worth the money to buy the more expensive baluns online, $6 + ship vs $2 local?

3) Does anyone have a link for a radiation plot for an RCA ANT751 antenna?

 

Thanks!

post #10164 of 10423
^ ^ ^

I've never heard of anyone having so much trouble with a balun. smile.gif

I used to have an "outdoor" balun and it was constructed better than the typical balun. It looked like this, wire instead of twin lead.

http://www.solidsignal.com/pview.asp?p=CM3075&ss=29488

Try taping the body of the balun to the antenna boom to prevent flexing.

As far as I can tell there is no published pattern for the ANT751 but you can bet the pattern is very wide, probably in the range of 60 degrees and F/B ratio will be low. There aren't enough elements to expect much more.

Chuck
post #10165 of 10423
Quote:
Originally Posted by Calaveras View Post

^ ^ ^

I've never heard of anyone having so much trouble with a balun. smile.gif

I used to have an "outdoor" balun and it was constructed better than the typical balun. It looked like this, wire instead of twin lead.

http://www.solidsignal.com/pview.asp?p=CM3075&ss=29488

Try taping the body of the balun to the antenna boom to prevent flexing.

As far as I can tell there is no published pattern for the ANT751 but you can bet the pattern is very wide, probably in the range of 60 degrees and F/B ratio will be low. There aren't enough elements to expect much more.

Chuck

 

The wire breaking didn't surprise me, it gets awfully wind on the roof. But the failed second balun with only VHF was a surprise. I thought these devices were simple and bullet proof the way they are sealed up but somehow I got one that failed. Bad luck I guess.

 

I tried tie wrapping the replacement balun to the boom to prevent swaying in the wind and get some strain relief on the wires but when I checked my channels it wrecked my UHF reception on a number of channels so I dropped it back down.  I read somewhere that the balun/twin-lead should hang down away from the boom or it can interfere with reception but of course that configuration causes strain on the wires.  This result was why I decided to add the twin-lead extension to the old balun and also solder and reinforce with shrink wrap all the connectors to make it CAT5 Hurricane rated balun but I didn't think I'd need to install it until spring. 

 

I was looking for a radiation plot to help me aim my antenna better.  San Bruno Mt and Sutro are aligned at ~340 degrees and is the direction my antenna is aimed. I pickup a number of station from the back of the antenna coming from Allison Mt in Fremont at 93 degrees. However, I am having trouble receiving a signal for KTNC coming from Diablo Mt at 42 degrees (VCH42, RCH14, I really want This TV because they show some good movies). I get KTNC but with a lot of dropouts and pixilation so I was hoping the ANT751 had a side lobe I could aim at 42 degrees, whereas the other station's signals are so strong I think cheating my aim East might improve KNTC without losing my other stations.

post #10166 of 10423
Quote:
Originally Posted by dmfdmf View Post

I was looking for a radiation plot to help me aim my antenna better.  San Bruno Mt and Sutro are aligned at ~340 degrees and is the direction my antenna is aimed. I pickup a number of station from the back of the antenna coming from Allison Mt in Fremont at 93 degrees. However, I am having trouble receiving a signal for KTNC coming from Diablo Mt at 42 degrees (VCH42, RCH14, I really want This TV because they show some good movies). I get KTNC but with a lot of dropouts and pixilation so I was hoping the ANT751 had a side lobe I could aim at 42 degrees, whereas the other station's signals are so strong I think cheating my aim East might improve KNTC without losing my other stations.

The idea of a directional antenna is to reject signals from as many directions as possible that are not in the main lobe. Have you tried pointing the antenna at about 10 degrees to see what happens? It might be good enough to get KTNC without losing SF stations. Who knows about Fremont.

Chuck
post #10167 of 10423
Quote:
Originally Posted by Calaveras View Post


The idea of a directional antenna is to reject signals from as many directions as possible that are not in the main lobe. Have you tried pointing the antenna at about 10 degrees to see what happens? It might be good enough to get KTNC without losing SF stations. Who knows about Fremont.

Chuck

 

Yes, that was why I wanted to see the radiation plot. I posted the same question in the antenna hw forum and someone posted a link to Winegard HD7000R plot which is almost the same antenna as the ANT751. Someone else said that Winegard makes this antenna for RCA/Audiovox.   The channel I am trying to pickup is RCh14 and this antenna has the widest beam width at that frequency so I think your suggestion will work.  Right now I am at 340 degrees and I think I might rotate toward North by 10 degrees to 350 degrees and that should allow me to pickup KNTC VCh42/RCh14 without knocking my main stations out of commission.  As far as Fremont towers are concerned I am not too worried as the only station that I care about is KICU VCh36/RCh36 but that station is so strong I am able to pick it up with a paper clip sticking out of the back of my TV input.  However, I am also picking up KGO VCh7/RCh35 from Fremont and it comes in handy as sometimes the weather knocks out KGO VCh7/RCh7 on VHF coming from Sutro or San Bruno so I'll just have to see how that goes.  Antenna tuning is a black art, not a science.

post #10168 of 10423
dmfdmf - Thanks for that other link. Glad to see my guess on the beamwidth and F/B wasn't too far off. smile.gif

Chuck
post #10169 of 10423

I noticed that VCh5/RCh29/KPIX/CBS out of SF has no sub-channels, does anyone know why they don't run sub-channels? Is this just a business decision or are there technical limitations?

post #10170 of 10423
Quote:
Originally Posted by dmfdmf View Post
 

I noticed that VCh5/RCh29/KPIX/CBS out of SF has no sub-channels, does anyone know why they don't run sub-channels? Is this just a business decision or are there technical limitations?

Hi,

 

A business decision.

 

Why it was made escapes me and others.

 

It is a national wide decision. You will note that KBCW also has no sub-channels which is also owned by CBS.

 

You can look up the ownership on RabbitEars.

 

http://www.rabbitears.info/market.php

 

"Historical, Ownership, Transition, and Translator Data" at the bottom when you click on a station after selecting a market.

 

SHF

 

Edit:

 

Quote:
Because of the tradeoffs, stations owned by CBS Corporation that are a part of CBS Television Stations (which include CBS O&O's, CW O&O's, and some independent stations) are not permitted to have digital subchannels.

http://en.wikipedia.org/wiki/Digital_subchannel

 

 

But this post says they are coming:

 

http://www.avsforum.com/t/1325575/cbs-o-o-stations-to-add-subchannels

 

Read past the first post, there are some made this month.


Edited by SFischer1 - 2/23/14 at 10:47pm
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