homade dipole for vhf - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 78 Old 06-25-2009, 06:43 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Howdy all I'm new and don't know if I'm butting in ,in the wrong place. I lost my channel (3, kiem Eureka CA) in the digital switch. They are now 3.1, but still VHF. The digital signal is too weak. As I'm only after one channel I want to try a custom dipole instead of an amp. We are off the grid and any fraction of an amp adds up. I have lots of room, lots of coax, and lots of copper, (solid core, maybe 12G)

Question, if I make say a 12, 25, 50 foot simple "T" dipole could that help? I know their direction, but not the MHz Any thoughts? On that scale would the length be specific for their VHF brodcast? Thanks, Don.
thatdonguy7 is offline  
Sponsored Links
Advertisement
 
post #2 of 78 Old 06-25-2009, 08:10 PM
AVS Special Member
 
ChrisPC's Avatar
 
Join Date: Sep 2005
Location: Nashville, TN
Posts: 1,248
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
You could definitely make a VHF dipole out of copper. Plenty of people have done it. According to the FCC, KIEM is on Channel 3, which would need a dipole of about 92 inches, for a half-wavelength. You could cut a quarter-wavelength of 46 inches, too. That's what most commercial antennas use.
ChrisPC is offline  
post #3 of 78 Old 06-26-2009, 01:22 AM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
92 inches THANK-YOU Chris! I've been googleing everywhere and calling Kiem. Came up with a complicated equasion that needed the MHz that I don't have. Now that I've tapped the bottomless source of all the info I seek: can I get a stronger signal by going longer? ie 92x8 is 61.3 feet? Does the gap in the middle matter much? and should I expect any cirtian resiistance parameter between the center copper and the outer?

For your info I offer this next post in return. It works.(54Mbps at the moment)
thatdonguy7 is offline  
post #4 of 78 Old 06-26-2009, 01:32 AM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hi. Some of you will not be interested in this techno-gibberish that follows. Longer story shorter, I now have relatively high speed Internet at my place roughly 6mi. from the border and 6 mi. to the water, with no conventional power or wires. Marcia my friend/tenant/neighbor has Hews-net satellite Internet . It's $70/Month. So that split is $35.
Firstly there is the dongle. I'm learning / told that is what you call any thumb sized thing you stick in a USB port. wireless network adapter is the key line for this. I put a newer N band router on Marcia's Hews-net modem. That works great for her house and one or two hundred feet . I'm 500 feet, through the trees , so I Mgivered something.
I cut a roughly 3X 3X 2 block of redwood and screwed it to the center of an old dish-network dish I got at the dump. In that block I drilled a hole to fit a ¾ PVC pipe that run's Long.
One rare Sunny day last week put soapy water on the dish and stuck foil on it, then pointed it at the (rare), sun. With welding goggles, (very bright on bare eyes), I figured the focal point of the probabla. ( those dishes are not truly parabolic, they flatten the area where the LNB fits.) That done I cut the pipe and attached the dongle to the pipe in the area of the focal point.(and to a ten foot USB extention)(foot-note, I simply felt the heat with my finger, also I got it wet and watched to see where it dried out first).
.So, anyway, with this I get four bars, and speeds ranging from 11 to 56 Mbps. I'm tethered to about six feet of USB .
I'm using a G band adapter on the N band router. I'm told that maybe I lose speed, but not distance with this Miss-match.
Next is the powering up of Marcia's modem and router. (I can't expect her to get up at midnight to turn on her inverter) I solved this by putting a double pole, double through switch at Marcia's house. I ran about 540 feet of wire from my inverter to the two upper poles of her switch. The lower two she can power from her system. The middle throw can be up or down. (hooking Miss-matched AC is reserved for the Fourth of July). Never the twain shall meet
So she leaves it up, switched to my power untill she wants to log on, then puts it back when she's done. Ether Way the router is on when we want it!
Lastly, get this . YOU got 500ft+ of wire handy? I had a 1000 foot spool of coax in the barn. I taped one end to a pool cue. Used that as a shuttle to push the coax through the thick brush 500 feet to Marcia's. Thankfully it was a cool drizzley day. The yellow-jacket hive I went past left me alone as I was moving like a sloth then. I wanted it on the ground so falling trees and limbs won't hit it. Also though on the rodents. They can chew into the outer webbing, but are unlikely to get through or cause a problem. First I checked voltage here, 111V, then I went there 111V. Then I hooked up the load,(router&modem), SAME! 111V!
NOW I'M A YUPPIE TOO !!!' Don.
thatdonguy7 is offline  
post #5 of 78 Old 06-28-2009, 12:18 AM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Tried 184 inches-nothing. Cut it to 92 and got a 17 -18 signal, not really watchable. Thinking of a "butterfly" of 6, 46" ? Don
thatdonguy7 is offline  
post #6 of 78 Old 06-28-2009, 07:51 AM
AVS Special Member
 
ProjectSHO89's Avatar
 
Join Date: Feb 2009
Posts: 2,688
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 72
Post your TVfool plot so we have some idea of what signal you're trying to work with.

using a longer wire won't give you any additional gain. For that, you'll need to add a reflector and one or more directors in echelon in order to achieve any increase (gain) in the signal strength.
ProjectSHO89 is offline  
post #7 of 78 Old 06-29-2009, 12:13 AM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thank-you Project. I need to do research on "TV fool plot" and "echelon" , before I can post an intelligent reply. #1 has all I know about KIEM CH 3 in Eureka CA. D.
thatdonguy7 is offline  
post #8 of 78 Old 06-29-2009, 04:59 AM
AVS Special Member
 
ProjectSHO89's Avatar
 
Join Date: Feb 2009
Posts: 2,688
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 72
Quote:
Originally Posted by thatdonguy7 View Post

Thank-you Project. I need to do research on "TV fool plot" and "echelon" , before I can post an intelligent reply. #1 has all I know about KIEM CH 3 in Eureka CA. D.

www.tvfool.com

http://www.hdtvprimer.com/ANTENNAS/types.html

These will get you started.
ProjectSHO89 is offline  
post #9 of 78 Old 06-29-2009, 11:28 AM
AVS Special Member
 
Rick_R's Avatar
 
Join Date: Dec 2000
Location: Simi Valley, CA USA
Posts: 3,213
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 12
When setting up my son's TV in his apartment I used a FM dipole antenna taped to the wall and got all OTA stations solid. This was 3 years ago before the transition. FM dipole antennas are cheap and already made.

Rick R
Rick_R is offline  
post #10 of 78 Old 06-29-2009, 04:12 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hi Rick. I put the 92 in. dipole I made with Chris's info half way up my mast. (as high as I could safely go), It does better than the Sears unit at the top. D.
thatdonguy7 is offline  
post #11 of 78 Old 06-29-2009, 11:46 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Holey Cow Project! TV fool (.com) is a tad enlightning ! amazing. Bedtime.Thanks again.D.
thatdonguy7 is offline  
post #12 of 78 Old 06-30-2009, 11:09 AM
Member
 
josrq's Avatar
 
Join Date: Jan 2008
Location: Simpsonville, SC
Posts: 141
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 10
Don,
From your location description, it sound like you are not far from Smith River. Is that right? If so, I would like know your successful antenna setup and which channels you recieve. I have a daughter in Brookings who needs a home brew antenna in order to get some channels.

Thanks for your help!
John
josrq is offline  
post #13 of 78 Old 06-30-2009, 11:58 AM
 
BCF68's Avatar
 
Join Date: Apr 2009
Posts: 2,463
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 19
I have a question. I made a simple dipole and when I hook the pre-amp to it seems to make the signal worse not better. The pre-amp works fine when attached to my DB4.
BCF68 is offline  
post #14 of 78 Old 06-30-2009, 12:02 PM
Member
 
kedirekin's Avatar
 
Join Date: Jan 2009
Location: Minnesota
Posts: 146
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I'm assuming the dipole is for a VHF channel. DB4 is a UHF antenna. Is your amp perhaps UHF-only?
kedirekin is offline  
post #15 of 78 Old 06-30-2009, 12:10 PM
 
BCF68's Avatar
 
Join Date: Apr 2009
Posts: 2,463
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 19
Quote:
Originally Posted by kedirekin View Post

I'm assuming the dipole is for a VHF channel. DB4 is a UHF antenna. Is your amp perhaps UHF-only?

No it's for both. In fact it says it has more gain for VHF than UHF. And yes I'm using it for VHF. Mainly for Ch 5( RF 5 ). Ch 4( RF 10 ) and Ch 8 ( RF 8 ) seem to come in as good as one can expect, but they also come in with my DB4 so really I only need the diploe for Ch 5. So I'm trying to tweak this thing for Ch 5 if it gets in the other 2 that's a bonus.
BCF68 is offline  
post #16 of 78 Old 06-30-2009, 05:12 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hi John, yes. I can see the Oregon coast from here. You might be betting on a plug horse though. I'm pretty green relative to this company! I will post my (eventual) result, but I AM at 1400 ft. Brookings of course is not. Don.
thatdonguy7 is offline  
post #17 of 78 Old 06-30-2009, 05:24 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
John. I CAN tell you that KEET 13.1/13.2 publick (PBS) is VHF, and south, and that the dipole I made with two slightly shorter than 46" pieces, (for a 92" with a small gap for connecting) DOES work barely for KIEM 3.1 UHF, also south. That does nothing for UHF.D.
thatdonguy7 is offline  
post #18 of 78 Old 06-30-2009, 09:10 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hey John, I got the VHF and UHF backwards. KEET is Ultra, and KIEM is Very high freq.D.
thatdonguy7 is offline  
post #19 of 78 Old 06-30-2009, 10:42 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
OK Project, I'm now on the same page. I happen to have a really nifty piece if stainless steel the right shape for a reflector. Since winds here (rarely) hit 100mph, I'm thinking of trying the echelon design at 92 for VHF Ch 3 instead. I'm a bit confused over those stupid? 75 ohm or 300 ohm resistors I normally put ON the antenna, to the coax. I'd rather solder that bullet-proof and deal with ? Impedance? Down here. I happen to have an old SWR meter from a CB guy. Don't know if that could help. I know enough about waves to understand cancellation. I would think there might be an issue with multiple horizontal elements. Maybe I'll find help in, http://www.hdtvprimer.com/ANTENNAS/types.html Any thought's? Don.

My dog of 12 years has gotten so good at figuring out where I'll go next, then being in the way, now all I need to do is check the dog to see where I'm going! D.
thatdonguy7 is offline  
post #20 of 78 Old 06-30-2009, 10:54 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I should have said,"any thoughts, anyone?" Don.
thatdonguy7 is offline  
post #21 of 78 Old 07-01-2009, 06:44 AM
Member
 
kedirekin's Avatar
 
Join Date: Jan 2009
Location: Minnesota
Posts: 146
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
The 75 ohm/300 ohm things aren't resistors, they're matching transformers and baluns (or both).

Baluns match balanced sources to unbalanced loads (I can never remember if the antenna is balanced or if the cable is). Without a balun, your cable effectively becomes part of the antenna, with unpredictable (and often bad) results.

A 75-to-300 ohm balun also acts as a matching transformer. Antenna's are often 300 Ohms. Shielded coax cable (for TV) is usually 75 ohms. This impedance mismatch will reflect a lot of the signal back to the antenna, preventing it from getting to your TV. A matching transformer minimizes the reflection, maximizing the amount of signal getting to your TV.

Shielded 75 ohm coax is much easier to deal with than unshielded 300 ohm twin lead, and it's a good idea to have some sort of balun up on the antenna. Since your going to want some kind of dongle up on your antenna, you might as well make the dongle a matching transformer and take advantage of the simplicity of coax.
kedirekin is offline  
post #22 of 78 Old 07-01-2009, 01:18 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks Kerirekin. Now I'm thinking of a Yagi reflector, although I don't know when I'll have time to whittle one of those. Was looking for dimentions of Channel Master 4248 when I found this general antenna info.
http://www.scribd.com/doc/7167010/An...gn-Other-Style
thatdonguy7 is offline  
post #23 of 78 Old 07-02-2009, 04:16 PM
AVS Special Member
 
TomCat's Avatar
 
Join Date: Jul 2000
Posts: 2,406
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 12
Quote:
Originally Posted by thatdonguy7 View Post

Howdy all I'm new and don't know if I'm butting in ,in the wrong place. I lost my channel (3, kiem Eureka CA) in the digital switch. They are now 3.1, but still VHF. The digital signal is too weak. As I'm only after one channel I want to try a custom dipole instead of an amp. We are off the grid and any fraction of an amp adds up. I have lots of room, lots of coax, and lots of copper, (solid core, maybe 12G)

Question, if I make say a 12, 25, 50 foot simple "T" dipole could that help? I know their direction, but not the MHz Any thoughts? On that scale would the length be specific for their VHF brodcast? Thanks, Don.

I built my dipole by cutting it to the wavelength of 36, which is in the middle of the band I receive and the most problematic channel. It is basically twinlead taped to a 2nd-story window, and receives high-V and UHF great from 21 miles away. But 3 means a much longer dipole. I am not sure cutting to the wavelength will really buy you that much gain. Plus, a dipole only has about 3 dB of gain at the max, and is not very directional. Here is a little Java calculator to figure out the size:

http://www.qsl.net/w4hn/antennaCalc.htm

Channel 3 returns a dipole of 7 ft, 7 and 23/32 inches.

It is unlikely, but possible, I guess, that a station would choose a low-VHF channel for DT, as it is susceptible to impulse noise which could thwart reception. Almost all DT is high-V or UHF, and most of those who were originally allocated low V unfortunately (such as Chicago CBS 2, which was a nightmare to receive on 3) have gone to a better high-V or U channel after 6-12-09. I would check first very closely to be sure that their physical channel is indeed 3 (3.1 may be a virtual channel, a remap from any other physical channel).

Assuming it indeed is channel 3, if distance is your true problem (as yet undetermined), and as you say, you have the room, I would look into this:

http://www.tpub.com/neets/book10/42o.htm

http://kyes.info/antenna/build.html

Which is about rhombic antennae. Large, cheap and easy to build, and very good for DX-ing distant TV signals. All you need is about 300 ft or so square of land (they don't require height or line of sight). They can give 20 dB of gain. About the best antenna you can buy only gives about 12 dB. Slap a Channel Master preamp on the output, and it should pull in anything up to and just past the curvature of the earth. There's a good chance that you may be able to get away without a preamp, though.

If that is your problem (distance/low gain), then a rhombic is just what the doctor ordered. But that might not be your real problem, it might be multipath interference. Directionality is then what you are after. Typically the more gain the more directionality, and vice versa, but I do not know if this is true of the rhomboids; more research can probably determine that, however. Apparently, increasing the sides of the rhomboid to multiple wavelengths increases directionality, so build it as big as you can.

If a dipole really is the answer, you might find this article about how to build one interesting as well:

http://www.tackyliving.com/article.php?id=61

There's no place like 127.0.0.1
TomCat is offline  
post #24 of 78 Old 07-02-2009, 05:33 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Wow tomcat, thank-you. I'm getting really flustered that I still don't know KIEM,s Mhz. They are about 80 mi. but there is a repeater that I'm not sure channel fool shows. (red mtn.) I have 50 "irons in the fire" My tenant here can't blow dry her hair cause of some glich with her generator. The sky is falling. I'll call KIEM again. Thanks, Don
thatdonguy7 is offline  
post #25 of 78 Old 07-02-2009, 06:36 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I actually got on the line with KIEM finally. 63Mhz they say. An 86 7/8in. "folded" he said.
If I understood right he meant that is a loupe. Thinks it should work with a 75-300 balun.
Success at hand? M's hair is first. D.
thatdonguy7 is offline  
post #26 of 78 Old 07-03-2009, 10:02 PM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The link http://www.qsl.net/w4hn/antennaCalc.htm Is golden for a simple dipole if the actual Mhz. is known. (it also gives buildable Yagi dementions). Too bad tvfool.com doesn’t show Mhz. Gonna now try the folded dipole that the KIEM engineer described , (above), BUT


The RHOMBIC ANTENNA in http://www.tpub.com/neets/book10/42o.htm seems to have real potential. I need to find dimensions, angles, what resistor, and if I use a Balun. I’ve been here for 30 years. Thanks to Project and Tvfool I see that there are a number of potential “targets” I didn’t know existed. Thanks all. D.
thatdonguy7 is offline  
post #27 of 78 Old 07-03-2009, 10:47 PM
Member
 
NTNgod's Avatar
 
Join Date: Nov 2006
Location: SE Wisconsin
Posts: 194
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 15
Quote:
Originally Posted by thatdonguy7 View Post

I'm getting really flustered that I still don't know KIEM,s Mhz. They are about 80 mi. but there is a repeater that I'm not sure channel fool shows. (red mtn.)

Wikipedia lists 10 translator stations for KIEM, only 3 of which are listed in the FCC database (which TVfool gets its data from), according to the entry.
NTNgod is offline  
post #28 of 78 Old 07-04-2009, 02:17 AM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Well, the 87 7/8 in. folded dipole I cooked up worked only slightly better then the 92in, plain, Di.Pole, or my Sears "Unit". I'm still knotted. I'm trying the diploe's on my mast about 8 feet up from the roof, where I can reach, but the other antenna is only 6 more feet up.
From what I have learned through you-all, as well as fidleing around a bit with the 92 (disconected) while changing to the folded, they seem to recoginize each-other. (putting the disonected 92 "in front", zeroed the signal.
As far as translators, If Crescent City is transmitting, I haven't picked that up. Maybe it's cable.
thatdonguy7 is offline  
post #29 of 78 Old 07-05-2009, 01:17 AM - Thread Starter
Member
 
thatdonguy7's Avatar
 
Join Date: Jun 2009
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Now nothing makes sense. I pride myself in being a “walking encyclopedia” , on most things that do something. Seems that antennas and there “tackle” are somewhat fickle.

I brought down my mast today. Back to basics. Make sure the wires are connected. The “thinge?/balun/ “ Is old ,large grey w/fine cracks, says matching transformer, Tawan. Has 2 ohm’s everywhere except lead to lead is .8.

A new one I have seems to be an open circuit, and yet another old one seems to be a short all around.

I carefully straitened the elements on my Sears Antenna, (because of what I’ve receintly learned.)

http://www.sears.com/shc/s/p_10153_1...0070921x00003d

and extended the mast, maybe 7 feet higher. Used the grey balun since it was not a short, or open. I think I have my mast almost at high as I can, so I cut 10 ft. Off my coax. AFTER that the week 13.1 (PBS, KEET) went away, but I now get anoluge 18 and a weak Dig. 29! (I love the Siempson’s) . From what I hear from tomcat, it sounds like my wire became part if my antenna.

I “offer” these questions. Can I check a balun, and what resistance might I seek? Even a plummer/carpenter/wire’er/mechinic can guess that this thing matters. And it’s a bitch to change!

The other is any thoughts on the Rhombic antenna. Sounds hi-gain and multy directional. Anybody actually built or seen one?

Lastly, there is a major power artery, two sets of three lines, maybe 50 up , running E/W less than ½ mile South of me. (370,000V? I don’t know) My signal is South also. If it’s not in the way, I’m not clearing it by much. Thoughts on that? I’m already on a modified sign-wave inverter.

Got this from tomcat. Took me a bit to see that it is “informative humor” D.

http://www.tackyliving.com/article.php?id=61
thatdonguy7 is offline  
post #30 of 78 Old 07-05-2009, 06:08 AM
Senior Member
 
TV Trey's Avatar
 
Join Date: Mar 2006
Location: Sebring, Fl
Posts: 279
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by thatdonguy7 View Post

I actually got on the line with KIEM finally. 63Mhz they say. An 86 7/8in. "folded" he said.
If I understood right he meant that is a loupe. Thinks it should work with a 75-300 balun.
Success at hand? M's hair is first. D.

At 63MHz the "electrical length" of the dipole will be 89". Due to what is called "end effect" the electrical length is approx. 5% shorter than the physical length. The impedance of a dipole is 75 ohms whereas the impedance of a folded dipole is 300 ohms. In either case make sure they are isolated from the boom and or mast.
TV Trey is offline  
Reply HDTV Technical

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off