AVS Forum banner
1 - 20 of 76 Posts

·
Registered
Joined
·
69 Posts
Discussion Starter · #1 ·
I got north view window on top floor that is facing the Mt Wilson (35 miles) north direction where towers are (no obstructions to line of sight). *I made my own 8 wisker type HDTV antenna via instructions on internet made with 12 gauge copper wire instead of hanger (diagram picture attached). *Results are good for UHF channels which average strength is 50-60%. I even get a station 63 miles away in San Bernadino KVCR ch24 (17% strength bar) slightly north eastern direction. Strength bar for high vhf channels of 7 9 11 13 are 40-60% . But, there is a station called KFLA ch 8.1, 8.2, 8.3, 8.4 that eludes me with 0-10% which gives some intermittent of video and audio. KFLA is located at Mt Wilson. So distance is same as other UHF and VHF stations but signal is weaker - ? I am currently considering the winegard YA 6713 with an A/B switcher ($70) . I have my current home-brew antenna right up against the window. *I am not allowed to put antennas on the roof or outside wall (apartment building). * What is your opinion? Is there a specially tuned high vhf antenna I can build to solve this? The YA6713 is to huge to hang in my bedroom.

thank you*


Pete
 

·
Registered
Joined
·
10,880 Posts
You can try t his good cheap pair of VHF rabbit ears (leave off the UHF loop), or build a large 24" circular copper tubing antenna for VHF. Combine it to the UHF antenna you built, with a UVSJ



The problem with VHF is that indoor reception is often difficult, due to poor wall penetration and lots of interference sources in the VHF band from other electrical and wireless crap in your home.
 

·
Registered
Joined
·
16,749 Posts
Do you know if KFLA is a low or high powered digital broadcaster?

What data do you get about it using Antennaweb.org or TVfool.com for you addresse?
 

·
Registered
Joined
·
69 Posts
Discussion Starter · #5 ·
ARXAW thank you, I will give the circle loop and rabbit ears a try.

For the circle - do both ends go to balun? I always wondered if connecting like that causes short?


ProjectSHO89 thank you - the programing on this station is unusual - 8.1 Australian TV, 8.3 Old movies, women mud wrestling - very odd mix. I will give up if the antenna is too huge or expensive.


Walford thank you - TVfool reports: Max ERP: 0.300 kw Eff. Pwr: 0.190 kw

When I go to website of the station it says: KFLA-LD is a digital low-power television station licensed to Los Angeles, California. The station broadcasts digitally on VHF channel 8, and is the first station located at Mount Wilson to broadcast solely with a digital signal. KFLA went on the air on October 17, 2007. http://www.kfla.tv/index.html


Does that mean they are putting out a lower signal the any other station?


Attached pics: my window, Antennaweb and TV fool.




 

·
Registered
Joined
·
101 Posts
If arxaw's suggestions don't work, since you are interested in building one, I would suggest looking at these:
http://www.avsforum.com/avs-vb/showthread.php?t=1024739 . Post #11 has pictures showing the dimensions of the antenna (roughly, with a ruler placed alongside the elements); http://www.ham-radio.com/k6sti/vhftv.htm , plans for a simple high vhf yagi. I haven't tried either of them, but they're pretty simple and short. I have had problems with vhf 11 and 13, both low-powered, and I made a short 4 or 5 element antenna that seems to pull in 11 (I haven't yet tried it on a regular basis for consistency) built on measurements that I got from k7mem's yagi calculator: http://www.k7mem.*********/Electroni.../yagi_vhf.html . You could try making one tuned just for channel 8; his designs call for long booms, but you could just try the length of boom that you want and see what you get. Finally, the RCA Ant751 has received good reviews from a number of people, and I believe that the boom is about 15 inches shorter than the 6713. It may be available locally, and if it is returnable it would be risk-free. Good luck!
 

·
Registered
Joined
·
16,749 Posts

Quote:
Originally Posted by pvotlucka /forum/post/18280264


Walford thank you - TVfool reports: Max ERP: 0.300 kw Eff. Pwr: 0.190 kw

When I go to website of the station it says: KFLA-LD is a digital low-power television station licensed to Los Angeles, California. The station broadcasts digitally on VHF channel 8, and is the first station located at Mount Wilson to broadcast solely with a digital signal. KFLA went on the air on October 17, 2007. http://www.kfla.tv/index.html


Does that mean they are putting out a lower signal the any other station?


Attached pics: my window, Antennaweb and TV fool.

Yes, they put out a lower powered signal as shown by much the power level in your TV fool listing and as indicated by their status as a low powered station.
 

·
Registered
Joined
·
3,282 Posts

Quote:
Originally Posted by walford /forum/post/18279606


Do you know if KFLA is a low or high powered digital broadcaster?

What data do you get about it using Antennaweb.org or TVfool.com for you addresse?

I looked it up at the FCC's website (which serves as the database that TVfool and antennaweb.org accesses).


Here is the license data: http://www.fcc.gov/fcc-bin/tvq?list=0&facid=28566
 

·
Registered
Joined
·
10,880 Posts

Quote:
Originally Posted by pvotlucka /forum/post/18280264


ARXAW thank you, I will give the circle loop and rabbit ears a try.

For the circle - do both ends go to balun? I always wondered if connecting like that causes short?

Leave about 3/4" gap in the loop. Connect a balun wire to each end of the tubing. 3/8" tubing works well. It would look similar to this . The balun would connect at the gap, which could be at the top or bottom of the loop.

Quote:
TVfool reports: Max ERP: 0.300 kw

Does that mean they are putting out a lower signal the any other station?

That is a very low power transmitter.


Additionally, your picture indicates that the "Vs" of your antenna whiskers are bent too close together. They need to be spread wider.
 

·
Registered
Joined
·
16,749 Posts
That looks like a UHF antenna.

You can get antennas that are combo upper VHF(channels 7-13) plus UHF that are not as wide as models that also receive the lower VHF channels (2-6)
 

·
Registered
Joined
·
10,880 Posts

Quote:
Originally Posted by walford /forum/post/18281689


That looks like a UHF antenna.

The antenna image I linked to in my post above is a UHF antenna. It was only for comparison, to show him that the whiskers on his homemade UHF antenna (below) were too close together.

 

·
Registered
Joined
·
16,749 Posts
If he is trying to receive channel 8 then the length of the dipoles on a UHF antenna are not long enough for VHF signals.
 

·
Registered
Joined
·
10,880 Posts

Quote:
Originally Posted by walford /forum/post/18282107


If he is trying to receive channel 8 then the length of the dipoles on a UHF antenna are not long enough for VHF signals.

That's why I suggested he try a VHF antenna and combine it with his homemade UHF bowtie.
 

·
Registered
Joined
·
5,414 Posts
Even if there's enough signal level to get a signal from VHF via a UHF antenna, the main lobe will not be straight ahead at those frequencies.


A UHF antenna will likely pull in any high-band VHF signals via two split lobes, about 60 degrees off axis. The null would be straight ahead, so no signal will be picked up from the direction the antenna seems "aimed".
 

·
Registered
Joined
·
69 Posts
Discussion Starter · #16 ·
Thank you all for the good ideas to catching ch8. I tried the following today:

1) RCA rabbit ears - 0% on signal bar

2) 24 inch circle of 3/8 copper tubing with 3/4 inch gap - 12% on signal bar

3) VHF bow tie -12 guage copper wire 31 inch length - 12% signal bar

4) Channel master 4221 copy -The eight wiskers antenna was widened to five inches and then antenna spun around slowly to see if it would aligned split vhf lobes. I added some four 31 inch wires behind the wiskers to see if that wire would tap into the split vhf lobes. The 1x1 screen is only sold in bulk at $35 or more - so I rejected that option. -10% signal bar. I will keep eye out for small piece of screen to complete the vhf section.


The antennas (except rabbit ears) all had a similar response was very similar across:

Ch 8.1 - business channel - clear picture and audio is very low and choppy

Ch 8.2 - infomercial channel - clear picture and audio

Ch 8.3 - entertainment channel - picture will come in clear but little choppy with red and green squares popping on and off. No audio.

Ch 8.4 - spanish -clear picture and audio


I believe 8.2 and 8.4 look and sound better because it is being transmitted with more power just by picture/sound quality and ignoring the TV signal strength meter.


I think the only option now is to give the yagi a try. Maybe it can be mounted along the wall or hanging from ceiling aimed out window at transmitter.


Thank you for your help, knowledge and inspiration Arxaw, ProjectSHO89, Walford, Lemmalone and Kenglish. I learned a lot for all your comments about antenna design.





 

·
Registered
Joined
·
10,880 Posts
All of your ch 8-n sub channels are broadcast on the same frequency and at the same power.


The circle antenna in the picture looks awfully small. It should be 24" across , or 75.4" of tubing.
 

·
Registered
Joined
·
965 Posts
You could try building a blind for the channel 8 antenna. I saw a picture of one someone built a couple of weeks back. He was using it to avoid nearby multipath reflections, but I suppose a blind might also knock down co-channel interference.
 

·
Registered
Joined
·
69 Posts
Discussion Starter · #19 ·
I got a 24" across 3/8 thick copper ring up against the glass window with duct tape. Channel 8.(1-4) came in at 20-21%. All the channels behaved same as in the last post.


The other VHF channels 7-13 are pulling in at 72% - which is good.


Question: Is this circular shape mean I am using a UHF to catch a VHF?
 

·
Registered
Joined
·
69 Posts
Discussion Starter · #20 ·

Quote:
Originally Posted by deltaguy /forum/post/18318519


You could try building a blind for the channel 8 antenna. I saw a picture of one someone built a couple of weeks back. He was using it to avoid nearby multipath reflections, but I suppose a blind might also knock down co-channel interference.

One of the posts mentioned that there may be a competing signal from San Diego on ch 8. I have a TV on the south side which does not pick up any signal from the south using Channel Master copy 4221 facing that direction. I believe that is what your saying. The poor signal on the south side forced me to run a 50ft cable to the north side. Deltaguy can you tell me what blind is or looks like? I did search but could not find. Thank you.
 
1 - 20 of 76 Posts
Top