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.

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.

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)

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 3”X 3”X 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.

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

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.

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.

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.

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

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.

Holey Cow Project! TV fool (.com) is a tad enlightning ! amazing. Bedtime.Thanks again.D.

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

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.

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

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.

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.

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.

Hey John, I got the VHF and UHF backwards. KEET is Ultra, and KIEM is Very high freq.D.

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.

I should have said,"any thoughts, anyone?" Don.

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.

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/Antenna-Design-Other-Style

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

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

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.

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.

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 (http://en.wikipedia.org/wiki/KIEM-TV#Translators), only 3 of which are listed in the FCC database (which TVfool gets its data from), according to the entry.

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.

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_12605_05710296000P?vName=Computers%20&%20Electronics&cName=Televisions&sName=Accessories&psid=SHOPPING01&sid=IDx20070921x00003d

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

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.

I’m looking into Rhombic antenna’s. One article suggests leg lengths be multiple’s of ( the lowest) wavelength. Doesn’t mention subtracting 5% for that. I’m still looking for info on the resistor and balun. Thank you, D.

I’m looking into Rhombic antenna’s. One article suggests leg lengths be multiple’s of ( the lowest) wavelength. Doesn’t mention subtracting 5% for that. I’m still looking for info on the resistor and balun. Thank you, D.

The 5% won't make much of a difference for a rhombic. You definitely need a balun (the rhombic is balanced), and I believe that your terminating resistor should be 300 ohms (by symmetry).

Thank you Tvtray. I wonder if the same applies to a Rhombic antenna. There are some angles instead of ends. I still haven’t got a figure for the resistor on the end “terminating?”
Also weather a Rhombic antenna uses a standard matching transformer at the “business end”. I bought an $8 matching transformer from Radio Shack today. My meter shows an open circuit all around. I’m going to bring down my Sears ( LPDA), (cris, crosed), put the new transformer on it, then raise it yet another 7 feet then check that. My thanks to all.D.

And thank you nybbler,D.

Honestly I would just suggest getting one of these:

http://www.solidsignal.com/prod_display.asp?PROD=Y5-2-6&xzoom=Large#xview

and be done with it...No more aggravation and less dangerous going up and down on the roof...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_12605_05710296000P?vName=Computers%20&%20Electronics&cName=Televisions&sName=Accessories&psid=SHOPPING01&sid=IDx20070921x00003d

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

Thank you Tvtray. I wonder if the same applies to a Rhombic antenna. There are some angles instead of ends. I still haven’t got a figure for the resistor on the end “terminating?”
Also weather a Rhombic antenna uses a standard matching transformer at the “business end”. I bought an $8 matching transformer from Radio Shack today. My meter shows an open circuit all around. I’m going to bring down my Sears ( LPDA), (cris, crosed), put the new transformer on it, then raise it yet another 7 feet then check that. My thanks to all.D.

Yes, i would make each leg 5% shorter than the physical wavelength. With regard to the terminating resistor, i would use a 1 watt non-inductive carbon resistor with a value of between 330 to 390 ohm. The antenna's impedance should be very close to 300 ohms which will allow you to use a 4:1 balun and run 75 ohm RG-6 to your TV.

Don,

Belated thank you for the info!

John

Hey all, My thanks to every one of you. I learned loads from this, my first foray into a forum. I’m saving it and all the invaluable links that you all took the time to provide me. I ended up using the same RCA LDPA, (that has a UHF thingy), straightened VERY straight, on a (now) 40’ mast, with the matching transformer in the right place. Never did put an 89” dipole at the top with a known 75 ohm , balun? I now get the “target” 63Mhz KIEM Ch. 3.1 with a signal from 17 to 40. (not really watchable below 20 for me) TV Fool has it at 80 miles.

Now I WANT MORE! The Yagi, the rhombic ,as well as reflectors on a dipole all sound worthy. When I reappear I hope it will be a thread, “effective rhombic antenna for uhf/vhf/”. Again, really, thanks all for your time. Don

John, splicers,suggestion of the yagi might be good for your daughter for KIEM http://www.solidsignal.com/prod_disp...om=Large#xview since she might have a straight shot over the water an 89" folded dipole with that thing that converts to coax, a balun, or matching transformer might work. Do really want her to have more company over to watch
TV?

Splicer, since my first post the plot has thickened http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d618a8da8d26298 has "broadened my horizions" Don

Hi Tray. I just discovered that there is a "page two", just found your post. I've got the fire goen good and my swiss army knife here. I didn't get the details on how exactly to widdle that 1 watt non-inductive carbon resistor, Is that like a briquette? Seriously though, so multiples of 89” for 63 Mhz, as my lowest with regular cable and a standard Radio shack Balun? No mention of 4to 1 on the package. All I can see is “connects 300 ohm to 75” and “matching transformer” I really do want to try the rhombic antenna. To get higher then the six , what 370,000 volt power lines that feed Northern Ca. I’d need to put it 7-800 feet away. Wonder if that hair thin copper wire for motor windings could carry a signal that far. There is no other local interference unless I’m running the mower.

.

Hi Tray. I just discovered that there is a "page two", just found your post. I've got the fire goen good and my swiss army knife here. I didn't get the details on how exactly to widdle that 1 watt non-inductive carbon resistor, Is that like a briquette? Seriously though, so multiples of 89” for 63 Mhz, as my lowest with regular cable and a standard Radio shack Balun? No mention of 4to 1 on the package. All I can see is “connects 300 ohm to 75” and “matching transformer” I really do want to try the rhombic antenna. To get higher then the six , what 370,000 volt power lines that feed Northern Ca. I’d need to put it 7-800 feet away. Wonder if that hair thin copper wire for motor windings could carry a signal that far. There is no other local interference unless I’m running the mower.

.

It would be multiples of 178". If you have the space i would make each leg at least 4 wavelengths each. The 75 to 300 transformer is a 4:1 balun.

Fist question, is a “leg” straight, or is it one side? Without loosing any blood I was able to come up with two 100’+ , un spliced, lengths of 10 G insulated copper. Six 178” ‘s makes an even 89’ per/side.
Next question, besides weight and aesthetics, does the insulation matter?

Insulation is fine, it will protect the wire from the elements. With 2 100' lengths of wire you can make a 3 wavelength antenna. Each leg will be 44.5' long (3x178"/12). A leg is a straight section with 2 per side and 4 total.

Rhombic
I found one article that says the side angles should be 130 deg. I’m laying out wire and looking at my situation. It’s complicated with the slope, driveways, location of trees, and the size of the thing.
Stupid question, can I make it backwards with the terminating away from the signal and the balun towards it? I wouldn’t ask but with that I would only need <40ft of coax and the trees could be right.
TVFool it has a column “Power (d Bm)”. Could that be the frequency ? KIEM says they are about 63 Mhz, , TVFool has a “62.9” there.
Lastly, on TVFool they have designations, 1 edge, 2 edge and Los. That made me curious because the channels I’m getting have “1 Edge”, but it looks as there are closer stations with other designations closer.
Again, my thanks.

Here's a good link for a dual rhombic that matches to 300 ohms (a regular rhombic is around 600 ohms and would require an 8:1 balun).

http://www.cebik.com/content/a10/vhf/rh.html

You will have to sign up first, but it's free.

Ron

OK I carefully cut and made loops for connecting the two 89’leinghts of solid 14G copper, and marked the middle’s at 441/2’. TVFool’s direction is a bit off for two reasons. They have my address IN Crescent City, whereas I’m about five miles east. Also my magnetic declenation is 19 1/2 Deg. , witch doesn’t seem to mach their info. Anyway my target’s” are dead south. I ran about 140 feet of coax to a nice big Dug. Fir that happens to be a little over 100’ north of me. In the dark, with a little headlamp I pulled out the “hips” as far as I could. I’m sure I didn’t get close to a parellagram, or a rhomboid. The wrinkled wire is laying up and down across misc. wood , brush, and an aluminum canoe. Came in the house, flipped the switch , IT WORKED! Barely for a bit. This with an “open” where the terminating resistor should be. I tried it with them connected, no help there.
I spent more than a little time researching “rhomboids”, and rhombotic antennas. Really all I think I need to know now is how far so I spread the “hips”. (and how to whittle a one watt non conducting carbon resistor) So far I found that a rhomboid differs from a parallelogram only in that it’s sides are the same length, a leaning cube. One article gave me 130Deg. For the “hips”, that would put the ends at 50Deg. I solved Rubik’s Cube on my own, got “A’s” in algebra, but…no geometry. With those angles and 44 1/2 ft. legs. I still don’t know how far to spread the hips.
And thanks also to you Dock. I did log on and look. Don

You don't need a one watt resistor. The directions for stuff like that are for transmitters, not receivers.

You don't need a one watt resistor. The directions for stuff like that are for transmitters, not receivers.

Rhombic antennas used for transmitting lose nearly half the RF power in the termination system which use 200 to 400 watt resistors. A 1 watt resistor would be fine for receive only but not for transmitting.

So far it looks like the equation for the above triangle is a bit tough. Anyone building a rhombotic might be interested in this. http://www.mathwarehouse.com/geometry/triangles/.

I came up with for 37’7” width for a rhombic with 44 ½ foot legs, at 130 deg. in the middle and 50 deg. on the ends. This might work down to 63 Mhz. My thoughts on finding my right terminating resistor involve a strong brine solution, a slow drip of fresh water, and then sitting down and watching TV! I’m just a handyman but I think I can get from near zero resistance to near zero conductivity with this. (in a pill bottle) I have misc. nichrome wire and potentiometers somewhere, but I thought this might be interesting to try. Place your bets! I'm getting out the ladders.

Rhombic

Well, I got it up. The bugs and the light got me good.. I used plexy-glass for the ends. Self taping sheet metal screws seem to work OK. Would be better if I had some small nuts. Plexy-glass will split like a friend who owes money. Stop and come the other way ASAP while drilling the larger for cord.
I stopped with sort of a “cripoloed”. Three points are about 14’ up. The East “hip” I can reach at about 8’. Ended all out of wampus, not pointed right. Terminating is “open”, (plexigalss).
With this I am now watching the news on KIEM, which I couldn’t get when I started this thread. IT WORKS. The 14’th is my 50’th B’day. I might be away for a bit.
Trey, I’m almost $8 into this project already. (new balun). I’m in the dark on a one watt resistor. Could that be the capacity ? 330 to 390 ohms, I get. Here you can’t even get a decent radio from Radio Shack. Any thoughts? Don

Rhombic

Well, I got it up. The bugs and the light got me good.. I used plexy-glass for the ends. Self taping sheet metal screws seem to work OK. Would be better if I had some small nuts. Plexy-glass will split like a friend who owes money. Stop and come the other way ASAP while drilling the larger for cord.
I stopped with sort of a “cripoloed”. Three points are about 14’ up. The East “hip” I can reach at about 8’. Ended all out of wampus, not pointed right. Terminating is “open”, (plexigalss).
With this I am now watching the news on KIEM, which I couldn’t get when I started this thread. IT WORKS. The 14’th is my 50’th B’day. I might be away for a bit.
Trey, I’m almost $8 into this project already. (new balun). I’m in the dark on a one watt resistor. Could that be the capacity ? 330 to 390 ohms, I get. Here you can’t even get a decent radio from Radio Shack. Any thoughts? Don

If you are consistently getting the station you want, then i wouldn't worry about it. The resistor is used to give the antenna a more unidirectional pattern. If you want later on to add the resistor then i would recommend Mouser Electronics as they have no minimum order limitations.

OK . I got the rhombus fairly taught and straight. With an open at the termination point it does about ½ of what my Sears ant. does. (25/50). I strongly suspect that one of my variables it the signal transition. They have almost certainly been fiddling with their transmitter since June 12.
Another thing. My three wavelength (441/2”/leg)(for 62Mhz) rhombus is “downwind” of my nearly 40 ft mast , way lower. There is a little slope so it is 10 to 14’ up off the ground. Now on my sears it locks on to analogue Ch 14, which is Ch 28, Fox network. A bit fuzzy but a nice find!
As the puzzle unfolds I keep changing my goals. My next plan is to play around with the resistance at the terminating point. During the party I lost my bottle of brine. Don

An update on the rhombic. Today I got the all-time highest signal I’ve seen, a 70 from it! The Sears was also ranging in the 60’s but the rhombic still seemed to doing a tad better. I think Eureka was fogged in whereas it was hot here.
My goofy idea of the saline resistor in a pill bottle had the predictable result. On my first experiment today I came up with what would (consistently), read about 250 Ohm’s at first, then climb up past 800 within a minute or so. I can only guess that the current from the meter affects it. Lett’n that one go. It didn’t help, nor hurt much. Nor did connecting the terminating legs. So far “open” has been best.
Mouser did indeed have a 1 watt 330 Ohm resistor for about $2. Unfortunately they need $7 more to ship it to me. ½ the fun of the game for me here is to cook it up for nearly nothing. Now I’m thinking that if I refresh my memory of resistor color codes I might find one laying around somewhere. ( as a freshman in high-school Mr. Edwards had me tutoring that!). Also I guess I need to check it backwards. Won’t be hard.
If anybody has any thoughts on the questions in the above link # 44 that could be nice. If Tvfool is indeed giving the frequencies I might try a smaller rhombus inside the 89ft for Ch 28.

PS. Project, if you are still out there I just figured out what you meant by "post your tvfool plot" Again my thanks, Don

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d618a8da8d26298

dr1394 I spent a bit more time here. http://www.cebik.com/content/a10/vhf/rh.html, Very informative, thank-you. D.

Another option if you have access to any surplus electronics (like an old tube TV) - harvest a handful of 3K resistors and bundle them in parallel. Small resistors are typically 1/8 or 1/4 watt, so eight in parallel will get you to 1 watt or higher. Nine 3K resistors will give you 333 Ohms.

Though frankly, I have no idea why you'd need a 1 watt resistor for an antenna. I can't imagine a received signal, or even all signals combined, would be even as much as one milliwatt. Is ithe resistor needed to bleed off static electricity or something?

Another option if you have access to any surplus electronics (like an old tube TV) - harvest a handful of 3K resistors and bundle them in parallel. Small resistors are typically 1/8 or 1/4 watt, so eight in parallel will get you to 1 watt or higher. Nine 3K resistors will give you 333 Ohms.

Though frankly, I have no idea why you'd need a 1 watt resistor for an antenna. I can't imagine a received signal, or even all signals combined, would be even as much as one milliwatt. Is ithe resistor needed to bleed off static electricity or something?

don't dig into old tv sets for surplus parts unless you are skilled. tv sets can capacitively hold high voltages in them for a very long time, enough to kill or injure depending on the circumstances. and don't dig into microwave ovens either.

you are correct in not needing a 1W resistor in a receive antenna (at least if you aren't sitting on the transmitting antenna).

don't dig into old tv sets for surplus parts unless you are skilled. tv sets can capacitively hold high voltages in them for a very long time, enough to kill or injure depending on the circumstances. and don't dig into microwave ovens either.

you are correct in not needing a 1W resistor in a receive antenna (at least if you aren't sitting on the transmitting antenna).

I recommended a 1 watt resistor for physical considerations.

you are correct in not needing a 1W resistor in a receive antenna (at least if you aren't sitting on the transmitting antenna).

I recommended a 1 watt resistor for physical considerations.

yes a 1W resistor has beefy leads.

any size resistor could be mounted on an insulator which would provide the structure.

Though frankly, I have no idea why you'd need a 1 watt resistor for an antenna. I can't imagine a received signal, or even all signals combined, would be even as much as one milliwatt. Is ithe resistor needed to bleed off static electricity or something?
The terminating resistor for the rhombic antenna is used to make the antenna uni-directional. Without the resistor the antenna is bi-directional, which is only a problem if you have a strong signal off the back of the antenna.
The resistor goes at the end of the antenna facing the transmitter. The power that is lost in the resistor is from the unwanted direction.

A static charge can build up on an outdoor wire rhombic antenna (even in a snow storm), and it needs to have a path to ground through a high resistance to protect the preamp or tuner. But, that's a separate problem.

For more information on the rhombic, borrow a copy (even an old one) of the ARRL Antenna Book (not ARRL Handbook).

Didn't do anything with it today. I should have made my handle "Gomer". From what I see one answer for post #44 might be "yes, it receives backwards with the wrong/(NO?) resistor. I might be able to squeeze in a fourth wavelength and raise it to 20 something feet. (assuming a one inch gently twisted and soldered splice would be OK). I
johnpost, Guess if I get killed by a TV that would only be redundant if the one I have now has already killed me, but I don’t know it yet. Likely that is more likely. (but thank you)

Got a regular 330 Ohm resisitror from my local computer fix-ti guy. Probably better I don't go up there in the dark, again. It's body is roughly the size of a carpenter ant. Result tomorrow.

Again my thanks to all. The 3/4 wavelength rhombic maybe works a tad better for 3 (as planed) and 13. With weather and other signals popping up, then fading, as well as transmitter's changing..... Hard to tell if the resistor helped much.(didn't hurt!). All in all a sucessfull experiment. I'm 10/10.