[300ohm]



Quote:
they had a garbage can full of 38 inch un-cut arrow shafts and as I was looking the stock girl said I have some bigger stuff in the back if you want to look

and I almost fainted three cans full of aluminium tent poles she said the tents rotted but she saved the poles , and most tents use fiberglass now ,

just to shorten the story 20 dollars and I had a truck load !!

Great deal.

But arent the aluminum tent poles like 1/2 inch or larger in diameter ?

 

[kagolu]

Is there a definitive guide/glossary/post that covers the basics someone could point me to I'm a little lost(which is normal).

Thanks


edit: I made an wooden eight bay but it needs some refinements/tweaks.

 

[rabbit73]

What topics are you interested in?

 

[kagolu]



Quote:
Originally Posted by rabbit73 /forum/post/16902458


What topics are you interested in?

I'm lost with some of the terminology and if there are specific measurements I should following.

 

[rabbit73]



Quote:
Originally Posted by kagolu /forum/post/16902445


Is there a definitive guide/glossary/post that covers the basics someone could point me to I'm a little lost(which is normal).

Thanks


edit: I made an wooden eight bay but it needs some refinements/tweaks.

Unfortunately, this is a very long thread to read through, and the comments on construction are spread throughout it. There has been some talk about organizing the information, but it would be a huge task.


The way our north-of-the border friends have handled it is to break a long thread into mini threads each covering a different topic:
http://www.digitalhome.ca/forum/forumdisplay.php?f=186


I don't think that is the best way for this thread, which should stay intact to show the progress of technique, have an introductory post that describes various UHF antenna types with links to examples and gain charts, and become a sticky because of its popularity. (Like with Antennas, rotators, boosters/preamps... for wide-band VHF/UHF & EV's Best Top Rated DTV Indoor Antenna Review Test Round-Up Guide.)


If you could show us a picture of your 8-bay, mclapp, 300ohm, IDRick and others could make some suggestions about improving it. At least give us a description of the construction. If you mount the elements directly to the wood with screws there is usually some loss because the mounting point is at a high impedance which is the most sensitive part to loss. Are you using a reflector?

mclapp's design works well and he has posted dimensions and has a site with drawings & etc. When he gives the dimensions of the whiskers and bay spacing he states it as 10" x 9.5" which means the whisker length each side and the vertical spacing between the bays in that order:
http://www.frontiernet.net/~mclapp/Antennas/


There is a problem with 8-bay designs: When you combine the two 4-bays together there are good and bad ways to combine them. The Channel Master 4228 8-bay has been a popular antenna but the way the two 4-bays were combined was not optimum. In my case, the 4228 was only 1 dB better than the 4221 on one channel, most of the rest were about the same, and a few were weaker. However, my situation is unusual because my antenna is in an enclosed area. Which outdoor balun I used also made a difference because the feedpoint impedance varies a lot across the UHF band. The main advantage of the 4228 is the narrower horizontal beamwidth which helps a lot with some multipath problems.


If you give us the tvfool results for your location and tell us what channels you are interested in and what success you have had so far, we can give you better advice.

 

[kagolu]



Quote:
Originally Posted by rabbit73 /forum/post/16902546


Unfortunately, this is a very long thread to read through, and the comments on construction are spread throughout it.


If you could show us a picture of your 8-bay, mclapp, 300ohm, and others could make some suggestions about improving it. At least give us a description of the construction. If you mount the elements directly to the wood with screws there is usually some loss because the mounting point is at a high impedance which is the most sensitive part to loss. Are you using a reflector?


mclapp's design works well and he has posted dimensions and has a site with drawings & etc. When he gives the dimensions of the whiskers and bay spacing he states it as 10" x 9.5" which means the whisker length each side and the vertical spacing between the bays in that order.


There is a problem with 8-bay designs: When you combine the two 4-bays together there are good and bad ways to combine them. The Channel Master 4228 8-bay has been a popular antenna but the way the two 4-bays was combined was not optimum. In my case, the 4228 was only 1 dB better on one channel, most of the rest were about the same, and a few were weaker. However, my situation is unusual because my antenna is in an enclosed area. The main advantage of the 4228 is the narrower horizontal beamwidth which help a lot with some multipath problems.


If you give us the tvfool results for your location and tell us what channels you are interested in and what success you have had so far, we can give you better advice.

Thanks,

I think I can learn alot just from your post. Thank you.


Yes I did screw into the wood, no I'm not using a reflector. I didn't copy the 4228 I just essentially built a long single 8 bay antenna with 7" whiskers and spaced 7" apart.

I'm looking for good performance overall, if there is such a thing, 2.1 to 56.1.

The local I'm interested in stations are primarily east and south east everything else is probably to far away(Tampa), I live about 20 mile east of Olrando on a 140ft hill(a mountain in FL).


Edit: I have the antenna in the attic facing east.


I'll check out Mclapps's design/page also

 

[rabbit73]

7" is too short.


A well constructed 4-bay might be all that you need for your signals from the E and SE.


Attic loss is hard to predict. If your coax downlead is long you would need a preamp to make up for the coax loss.

 

[kagolu]



Quote:
Originally Posted by rabbit73 /forum/post/16902795


7" is too short and you will need some VHF sensitivity for NBC on real CH 7.


A well constructed 4-bay might be all that you need for your signals.


Attic loss is hard to predict. If your coax downlead is long you would need a preamp to make up for the coax loss.

I am using a preamp at the tv. The coax is probably about a 75ft run. 12db preamp if that sounds correct.

 

[rabbit73]

What preamp are you using? It should be the kind that comes in two parts and has a low noise figure.


The preamp should be near the antenna and its power injector (power supply) near the TV to amplify the signal BEFORE it goes down the coax.


A reflector would help.

 

[kagolu]



Quote:
Originally Posted by rabbit73 /forum/post/16902867


What preamp are you using? It should be the kind that comes in two parts and has a low noise figure.


The preamp should be near the antenna and its power injector near the TV to amplify the signal BEFORE it goes down the coax.


A reflector would help.

It's a one piece powered signal booster i picked up form Lowes. I could put it, or a proper booster if this isn't a good one, in the attic no problem.

 

[kagolu]



Quote:
Originally Posted by rabbit73 /forum/post/16902867


What preamp are you using? It should be the kind that comes in two parts and has a low noise figure.


The preamp should be near the antenna and its power injector near the TV to amplify the signal BEFORE it goes down the coax.


A reflector would help.

Would expanded metal like this make a good reflector? Ive got some around work.

 

[300ohm]



Quote:
It's a one piece powered signal booster i picked up form Lowes.

A Phillips amp ? They are one or two input distribution amps, that have a huge amount of noise. I tested one (because I got it on clearance for very cheap) and immediately took it back for another, it was way too noisy and distorted the picture. The second one did the same and I took it back for a refund, it wasnt even worth keeping for $10, heh.

Quote:
Would expanded metal like this make a good reflector?

Is that the flat stuff and not rounded/slanted out ? Its pretty heavy, but in an attic that doesnt matter. If you turn it sideways than its pictured, it would work better. The wires are wavy and not straight, but they are close enough together to act like a solid sheet at uhf, if the hole distances are about 1/2 inch.

 

[kagolu]



Quote:
Originally Posted by 300ohm /forum/post/16903067


A Phillips amp ? They are one or two input distribution amps, that have a huge amount of noise. I tested one (because I got it on clearance for very cheap) and immediately took it back for another, it was way too noisy and distorted the picture. The second one did the same and I took it back for a refund, it wasnt even worth keeping for $10, heh.



Is that the flat stuff and not rounded/slanted out ? Its pretty heavy, but in an attic that doesnt matter. If you turn it sideways than its pictured, it would work better. The wires are wavy and not straight, but they are close enough together to act like a solid sheet at uhf, if the hole distances are about 1/2 inch.

Yes it is a Philips amp. I'll check the thread for better recomendations.


Yes the expanded metal is flat and the space is about 1/2 inch wide. Weight isn't an issue like you said because I have to put it in the attic.

Thanks for the help.

 

[akahooper]

OK, HDP-269 amp on order - Check.


Been rummaging around on DHC for NARODs and I think I got the dim's I need. Will settle of 30.25" lg with reflectors 11.5" back. (Since I'm shooting for 7 & 11)


I think what I used for the layout is called a Gen1 GH6. (See attached) Question is, can I just add the collinear rod reflectors as per dim's on my attachment, and then the NAROD/NAROD reflectors from [DBGH_VHF_hi_Antenna.pdf] on this page?
http://www.digitalhome.ca/forum/show...t=99907&page=7


There seems to be so many different versions; GH6, GH8, GH10... with the NARODs, with/without reflectors, etc, etc... and info is all over the place - it's making my head spin!

So a few other questions...

The wire I used is #6, (.162" dia) not #8 as I previously stated. (Brain fart) I should add the NARODs using the same size, yes? Then using between 5/16"-3/8" dia for the NAROD & collinear rod reflectors should be a reasonable relationship? If I come down to 1/4" dia would this have an adverse effect on performance?


Also, it would appear that the spacing between the elements has grown considerably (from many of the photo's I've seen of DB & SB builds) from the 44mm (1.732") dim I have on my attachment. Where are we here, 85mm, 89mm??? And does this effect the reflector gap?


Unlike so many out there I only want to do this once, and not make it a life-long labor of love...

Thanks for all the help!

In the meantime I'll work on the PVC frame in my head...

 

[mclapp]



Quote:
Originally Posted by kagolu /forum/post/16902986


Would expanded metal like this make a good reflector? Ive got some around work.

I built one using metal just like that for a reflector, it worked fine. Just be sure to try to keep the diamond pattern as 300 ohm stated although with holes that small it may not make a difference.


Looking at your TVfool plot you should be able to get away with a single 4 bay 9 1/2" whiskers and spaced 9" apart. If you want to use wood for the frame that's fine, just use some PVC fittings or short lengths of PVC pipe as spacers to attach the whiskers and phaselines to. I would try it without the reflector first so you have the best chance of getting stations from multiple directions.


If you must use that amp mount it as close as you can to the antenna. I would suggest attaching a short length of coax from the antenna to a single TV without the amp to see what you have then work from there.

 

[300ohm]



Quote:
I think what I used for the layout is called a Gen1 GH6. (See attached) Question is, can I just add the collinear rod reflectors as per dim's on my attachment, and then the NAROD/NAROD reflectors from [DBGH_VHF_hi_Antenna.pdf] on this page?

Yep, on the Gen1 GH6 that will be fine. On some of the other models you really couldnt, because they were optimized just for those reflector rods on those models.

Quote:
The wire I used is #6, (.162" dia) not #8 as I previously stated. (Brain fart) I should add the NARODs using the same size, yes?

#8 and #6 are close enough and will be fine. The measurement is center of wire to center of wire.

Quote:
Also, it would appear that the spacing between the elements has grown considerably (from many of the photo's I've seen of DB & SB builds) from the 44mm (1.732") dim I have on my attachment. Where are we here, 85mm, 89mm??? And does this effect the reflector gap?

Long ago it was discovered that a wider feedpoint of 85mm to 105mm gives more gain. (too much spacing could result in decoupling) 89mm is the distance across a 1 inch tee, which I used. No effect on the reflector gap.

 

[300ohm]



Quote:
I built one using metal just like that for a reflector, it worked fine.

Heh, I used metal just like that on an attachment for my bagging lawnmower for mulching up leaves. I only wanted leaves mulched up smaller than those holes to pass thru. The stuff I had was pretty hard to cut thru.

 

[kagolu]



Quote:
Originally Posted by mclapp /forum/post/16904841


I built one using metal just like that for a reflector, it worked fine. Just be sure to try to keep the diamond pattern as 300 ohm stated although with holes that small it may not make a difference.


Looking at your TVfool plot you should be able to get away with a single 4 bay 9 1/2" whiskers and spaced 9" apart. If you want to use wood for the frame that's fine, just use some PVC fittings or short lengths of PVC pipe as spacers to attach the whiskers and phaselines to. I would try it without the reflector first so you have the best chance of getting stations from multiple directions.


If you must use that amp mount it as close as you can to the antenna. I would suggest attaching a short length of coax from the antenna to a single TV without the amp to see what you have then work from there.

Thank you for the great info! I'll let you know how well it works and post some pics of the build as well. Looks like I need my A game with all good stuff around here.

Is it possible to use more than one antenna wired in parallel with the first but facing different directions?

 

[jwwm_2]



Quote:
Originally Posted by kagolu /forum/post/16907841


Thank you for the great info! I'll let you know how well it works and post some pics of the build as well. Looks like I need my A game with all good stuff around here.

Is it possible to use more than one antenna wired in parallel with the first but facing different directions?

You should watch my video for some possible ideas if you go with McLapp's plan.

 

[RONNIE KD5YTE]

still sorting my find some are 12mm and some are 6mm tube and solid sharpened on one end (we are talking about aluminum tubing )the 12mm tubes have a elestic shock cord run thru them ,I think the smaller ones were braces or something,one part looks like it went at the top has 12 sockets to insert the poles into ,,

I hope to get my camera back this week , the battery messed it up and they sent it off for someone to tell them to send me a new one !!