I just got that VF from a website that had several listed.
If it is, then the length of the 75 Ohm transformer would be 5.9675' or 5' 11-5/8" - yet shorter than before.
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h.brew cubical quad,2,3 or 4 element w/pics
- Thread starter johnny9
- Start date
If it is, then the length of the 75 Ohm transformer would be 5.9675' or 5' 11-5/8" - yet shorter than before.
Belden's RG11 has an 84% "nominal velocity of progation"...
Data Sheet from belden.com.
I've seen others between 82% and 85% as well... Nothing anywhere close to 66% or 75%. You guys have any sources for those?
The DB
Data Sheet from belden.com.
I've seen others between 82% and 85% as well... Nothing anywhere close to 66% or 75%. You guys have any sources for those?
The DB
"most" RG-11 is close to .75 vf
Belden HDPE 9292 is listed as .84 vf
http://www.google.com/url?sa=t&rct=...vILQDw&usg=AFQjCNF0zmQDNdc2pgYUqUfnLjpuqHabLw
http://www.google.com/url?sa=t&rct=..._YGICA&usg=AFQjCNGXcZndJIgTFQKuh6x3WeZzuo7kaQ
Now that I look further I find RG11 comes in both PE and foam PE so the stuff can vary with the VF between .66 - 85 it seems.
Here is the 17th edition of the ARRL I used:
Here is a link that might help calculate your VF using a 259b.
Calculate velocity factor with SWR Analyzer
So, if you're going to phase something using coax then it is best to test the coax to be used. If the test and the meter are accurate then you might get better results.
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maybe this will help the variations of opinions..as im learning and you guys have been there..
my calculations are for chanel 40..i talk upper ssb mostly and it will cover almost 1.5 mhz spread.
one side of my driven element will be 9.168ft or 110.017 inches..total length of 36.672ft
251 divided x 27.4 = 9.26
x .84vf = 7.78
.78 x 1.2 = .936
so im sticking with 7ft 8 1/2 inches..i can always shorten it it up to adjust swr,s but you can never lengthen it with the same coax.
thanks for that link marconi
my calculations are for chanel 40..i talk upper ssb mostly and it will cover almost 1.5 mhz spread.
one side of my driven element will be 9.168ft or 110.017 inches..total length of 36.672ft
251 divided x 27.4 = 9.26
x .84vf = 7.78
.78 x 1.2 = .936
so im sticking with 7ft 8 1/2 inches..i can always shorten it it up to adjust swr,s but you can never lengthen it with the same coax.
thanks for that link marconi
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Coaxial cable velocity factor information
I just buy the 6' 75 Ohm cables, put adaptors on each end, and enjoy my match. I center on 27.385 MHz
I just buy the 6' 75 Ohm cables, put adaptors on each end, and enjoy my match. I center on 27.385 MHz
I matched my five-band quad: one RG213 feed to a remote coax switch, and 1/4 wave sections of RG11 to each driven element. I used an MFJ-259B to cut the RG11, and it all worked perfectly from the start. This way, you don't have to look up the VF. The instrument figures out what it is in the particular piece of coax you happen to be using and does everything but actually cut the cable and attach the connector.
id have to win the lotto lol..i just got my first exspensive meter and its prob not all that when it comes to meters and cash spent.but i really like this diawa cn-801 and dont plan on replacing it with ny other unless it breaks..
may get my first real base radio today so the antena on hold till i find more time.
rci 2995dx seems like it could be a good choice for a beginner like me..wish me luck
may get my first real base radio today so the antena on hold till i find more time.
rci 2995dx seems like it could be a good choice for a beginner like me..wish me luck
What? You BUY your matching sections? The king of making stuff outta other stuff??? :tongue:
I have a bunch of 75 ohm cable laying in my attic from previousl cable/dish installs. Anything wrong with using it?
73,
Brett
Nope, Nothing wrong with using it. I have.
I am also the student of improvisation. I see using the jumpers for purposes other than intended as being in the spirit of repurposing.
nothing wrong with repurposing well today i finally got a lil but more done but not much.
got 50 more ft of wire stripped.
got 7 alum 1/8th thick u shaped pieces made to keep the wire tight in the end of the f.glass rods,with a set screw.not in pics yet.
got the part made up for the connections and its low profile,and can be takin apart compared to the ebay dipole that is permanitly put together.
the metal thing on top will be where the fiberglass rod rests inside to keep it centered and straight..
most i see have the coax input at the bottom so i put mine on the side,and used a elbow so the coax will be a straight shot up the spreader arm.
i should have waited to start this thread as i didnt think it would be so long before i got to get things ready.:headbang
well today i finally got a lil but more done but not much.got 50 more ft of wire stripped.
got 7 alum 1/8th thick u shaped pieces made to keep the wire tight in the end of the f.glass rods,with a set screw.not in pics yet.
got the part made up for the connections and its low profile,and can be takin apart compared to the ebay dipole that is permanitly put together.
the metal thing on top will be where the fiberglass rod rests inside to keep it centered and straight..
most i see have the coax input at the bottom so i put mine on the side,and used a elbow so the coax will be a straight shot up the spreader arm.
i should have waited to start this thread as i didnt think it would be so long before i got to get things ready.:headbang
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No I didn't. When I decided to get rid of the yagi and do the quad, I went straight for the 4 element direct fed design.
BTW, I'm not real sure I'd do the 259 connector deal like you are. Just split the braid and center conductor and put ring terminals on them.
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i just copyed what i see all the time is all..it is supposed to attach to the end of the 3/8 f.glass spreader bar .i switched back to wanting vertical so maybe i could hear the locals better.
yours looks real nice but seems the wire pullin on it at an angle would make it relax and strectch a lil..got better pics with it hooked to the wire?
id sure rather do it the best way thats for sure..my neighbor has 2 quads and they have a similar thing i made iirc..his horizontal is square and it hangs in the middle of the wire.
i was gonna put mine in diamand shape like yours and the connector on the west end spreader bar.? what ya think.
yours looks real nice but seems the wire pullin on it at an angle would make it relax and strectch a lil..got better pics with it hooked to the wire?
id sure rather do it the best way thats for sure..my neighbor has 2 quads and they have a similar thing i made iirc..his horizontal is square and it hangs in the middle of the wire.
i was gonna put mine in diamand shape like yours and the connector on the west end spreader bar.? what ya think.
I didn't take any pics before I put it up, but the tension of the wire element goes to the plastic block, not the coax. The element and coax both attach at the same point on the plastic block. It's been up a few years now with no stretching.
I'm sure it'll work, it's just extra parts and extra weight that's not really needed imo.
Yep, that'll be vertical. I prefer the diamond over the square so the connection is as a spreader and not unsupported in the center of a wire run.
wow i like it,,i think i totally get it now..the 2 outter screws on the block go all the way thru and the coax and wire go on the 2 sides.
other screw looks like a "set screw" to hold the spreader still in the hole?
i was worried about weight on mine..i have some clear lexan plexiglass thats 1/2 thick iirc,,it should work and would be much lighter weight.
other screw looks like a "set screw" to hold the spreader still in the hole?
i was worried about weight on mine..i have some clear lexan plexiglass thats 1/2 thick iirc,,it should work and would be much lighter weight.