Coax ??

[Captain Kilowatt]

Well what was said was it took 3 feet to do a half wave I think. It’s just junk obviously. Just wanted to clear some things up by asking u guys. Great info from all u guys .. thanks

Don't listen to those guys. Since 11m has a wavelength of about 36 feet a half wavelength would be about 18 feet and allowing for most typical coax cables velocity factor the actual physical length would be somewhere between 12 and 13.5 feet...........nowhere near 3 feet.

 

[Captain Kilowatt]

Then you most likely were not aware that you could tune the antenna by putting several inches of aluminum foil on the coax and sliding along the coax while watching an SWR meter to get a 1 to 1 match. Not much of a Tech are you. LOL

LOL I remember when we used to make a stub out of 300 ohm twin-lead and attach it to the cable TV coax and use a piece of foil to tune the stub to descramble the pay channels. LOL

 

[OldTech03]

LOL I remember when we used to make a stub out of 300 ohm twin-lead and attach it to the cable TV coax and use a piece of foil to tune the stub to descramble the pay channels. LOL

Yea I remember those cable boxes they had a long row of switches and some had a channel selector knob. I Remember modifing one for my Dad he was concerned it might be illeagal but it didnt stop him from using it.

 

[Redbeard U812]

Little short on time right now , but I will definitely read the link.

Can't always rely on internet access, so download it!

It's not a link, it's a download (a book actually), save it and READ IT!

By saving it you can research your antenna topic first and then discuss any topics which you don't understand. Realize, that relying on instant internet remedies is not learning, research what questions you have, and make some calculated assessments. These guys are great, willing to help, share information, guide you along...but do realize it's tax season, and most of us are really cranky right now.

You can download the ARRL Antenna Books from the web, but here is the Hall again and Reflections by W. Maxwell. The latter to me is better read, explains a lot through laymen's terms, kinda......

"Riddle me this Batman...".....and others out there in DX land....

Now....... did you know that there IS a twenty-one foot rule?

I'll really be stirring things up with this!

 

[S&W357]

Only three foot rule here is a couple of yardsticks.

 

[Mudfoot]

Yea I remember those cable boxes they had a long row of switches and some had a channel selector knob. I Remember modifing one for my Dad he was concerned it might be illeagal but it didnt stop him from using it.

Buddy of mine got sketchy with cable. Somebody stooled on him. Judge made him buy complete cable package including Showtime and HBO for a year. Lol, we were just talking about that a few weeks ago.

 

[M0GVZ]

The correct answer for the length is what is required to go from radio to antenna. If altering the length of the coax alters the SWR then you have a problem. It means that you have a poor RF ground so the antenna system is using the coax to try to compensate and by altering the length you therefore alter the tuning of the antenna system. In a system using either a balanced antenna like a dipole or using a properly installed antenna with a decent RF ground you will find no difference in SWR if you alter the length.

CBers and indeed some hams who found that altering the length reduced their SWR both believed the rubbish and perpetuated the myth because they didn't fully understand what was happening.

 

[Captain Kilowatt]

Buddy of mine got sketchy with cable. Somebody stooled on him. Judge made him buy complete cable package including Showtime and HBO for a year. Lol, we were just talking about that a few weeks ago.

When we first got cable out by home I got it without the two scrambled channels which back then were TMN (The Movie Network) and Family Channel. I made up a box that included a powered line amplifier and distribution board to run out to another cable line in the house going upstairs to the bedroom. It also had an old tunable FM broadcast band trap that was meant to be used on a receiver in an off-air relay site to avoid picking up other signals. It was meant to be used as a bandpass configuration and I set it up as a band stop configuration. I modified the tuned circuits in that trap so it covered somewhere around 135-155MHz since that was where the two scrambled channels were on the cable. There were a couple access holes in the case for tuning. It worked GREAT as the trap had such a high Q it would tune out the scramble pulses without affecting the video quality..........basically the same thing as the cable company installed inline for those who subscribed to those channels. All was going great until we had a problem with the cable. I forgot to remove the box before I went to work on the day the service tech was due to arrive. Thank goodness my wife was on the ball that day. The guy looked at the box sitting on top of the TV and asked suspiciously what it was for. The wife responded "My husband is a ham radio operator and he used to mess up the TV until he installed that thing and now he can talk on the radio and not mess it up. All I know is that now we are both happy". WHEW!! He could see by the tower and antennas in the yard she was telling the truth....or at least part of the truth. LOL He just said "Oh....cool" and continued to troubleshoot the issue. Good thing he didn't check the pay channels. LOL The problem ended up being outside in a splice on the main trunk line

 

[Beetle]

When we first got cable out by home I got it without the two scrambled channels which back then were TMN (The Movie Network) and Family Channel. I made up a box that included a powered line amplifier and distribution board to run out to another cable line in the house going upstairs to the bedroom. It also had an old tunable FM broadcast band trap that was meant to be used on a receiver in an off-air relay site to avoid picking up other signals. It was meant to be used as a bandpass configuration and I set it up as a band stop configuration. I modified the tuned circuits in that trap so it covered somewhere around 135-155MHz since that was where the two scrambled channels were on the cable. There were a couple access holes in the case for tuning. It worked GREAT as the trap had such a high Q it would tune out the scramble pulses without affecting the video quality..........basically the same thing as the cable company installed inline for those who subscribed to those channels. All was going great until we had a problem with the cable. I forgot to remove the box before I went to work on the day the service tech was due to arrive. Thank goodness my wife was on the ball that day. The guy looked at the box sitting on top of the TV and asked suspiciously what it was for. The wife responded "My husband is a ham radio operator and he used to mess up the TV until he installed that thing and now he can talk on the radio and not mess it up. All I know is that now we are both happy". WHEW!! He could see by the tower and antennas in the yard she was telling the truth....or at least part of the truth. LOL He just said "Oh....cool" and continued to troubleshoot the issue. Good thing he didn't check the pay channels. LOL The problem ended up being outside in a splice on the main trunk line

"Splice on the main trunk line", eh? Did he then cut the "green wire"?

 

[Captain Kilowatt]

"Splice on the main trunk line", eh? Did he then cut the "green wire"?

IIRC it was more chartreuse.

 

[Rwb]

Back in the mid 70s i loaded at a small manufacturing plant in arizona.it was very small sat lite dishes and a control box with wire,it was all in a box about 18"x10"x6". Was named cable bandit.i talked them out of 3 units.i rigged 1 on my truck as i had an inverter,1 for home and an extra. It picked up the movie channel and 2 others. 1 on house lightning killed,second 1 just quit and 1 on truck,some truckstop thief took the dish off back of my truck.but they worked fin.1 on truck was on a pole i made push up n twist a thumb screw when set proper,had nuff line on tv id set it where i could see it n tune the fish.i wrote approxamite aim via location as i ran basicly same routes