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antennas:qfh [2024/04/16 20:32] 2m0vsrantennas:qfh [2024/04/24 19:15] (current) 2m0vsr
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 From Scott - 2M0VSR: From Scott - 2M0VSR:
  
-https://jcoppens.com/ant/qfh/calc.en.php  generates the paper template for the holes. 
  
-Quadrifilar helicoidal antenna - Javascript on-line calculator+**Credits**
  
-Compared to solid core wire, it's quite easy to get it into shape, or close enough that it tunes almost smack centre in the band+Inspired by this build: https://tf1ez.com/qfh-antenna-build/
  
-I think the rods are M4/5/6 threaded rods. Just make sure the rod will go throw the stell banding holes as they are difficult to enlarge. +**Summary Instructions**
  
 +The above link has a better guide but the TLDR version is:
  
 +  * Generate and print the paper templates based on the type of PVC pipe you have.  Use: https://jcoppens.com/ant/qfh/calc.en.php 
 +  * Tape the cut-outs onto the PVC pipe, making due they are aligned down the pipe.
 +  * Drill out the holes. The centre ones are not strictly needed but you may find it useful to use some wooden dowel rods to support the banding.
 +  * Cut the threaded rods down to size based on the calculator. Leaving them a little long won't do any harm.
 +  * Put the threaded rods though and use a washer/nut against the PVC pipe to hold in place.
 +  * Cut the Banding so that it stretches to the opposite bottom rod. I'd leave a bit extra and trim.  
 +  * Use 2 nuts/washers to lock in place the banding on each end.
 +  * Attach the Coax ends to the top of the antenna and run it down the tube. Tie it off to the bottom with some zip ties for strain relief. 
  
-Think it was this that gave me the original ideahttps://tf1ez.com/qfh-antenna-build/+ 
 +**Notes:** 
 + 
 +  * You can use low gauge wire as an alternative to banding but it's much more difficult to work with and get aligned wellI used 10mm earth wire for an earlier build and it worked ok.
  
  
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   * - PVC Pipe (55mm, 1meter or similar)    * - PVC Pipe (55mm, 1meter or similar) 
   * - Galvanised Steel Banding - [[https://www.screwfix.com/p/ced-all-round-band-12mm-x-10m/18298 |Screwfix]]    * - Galvanised Steel Banding - [[https://www.screwfix.com/p/ced-all-round-band-12mm-x-10m/18298 |Screwfix]] 
-  * - 4 x Threaded Rods + Nuts + Washers  (Would probably go with M4 or smaller so that you don't have to cut the banding half-way though a whole.) [[https://www.amazon.co.uk/Pack-Stainless-Steel-Threaded-Bar/dp/B08NDQW87B/|Amazon]] [[https://www.amazon.co.uk/M4-Leryati-Standard-Stainless-Fastening/dp/B0BVZCH1XF/|Amazon]] [[https://www.amazon.co.uk/25mm-Flat-Washer-Stainless-Steel/dp/B0BVMPCVMY|Amazon]] +  * - M4 Threaded Rods (x4) [[https://www.amazon.co.uk/sourcing-map-Threaded-Thread-Stainless/dp/B0BK52F97W|Amazon]] 
-  * - Some Good Quality Coax. (Messi Hyperflex 5 / Ultraflex 7 for example)+  * - M4 Nuts (x24) [[https://www.amazon.co.uk/Nylock-Nylon-Insert-Locking-Stainless/dp/B07VSCG96L|Amazon]] 
 +  * - M4 Washers (x24) [[https://www.amazon.co.uk/25mm-Flat-Washer-Stainless-Steel/dp/B0BVMRXXVF|Amazon]] 
 +  * - Good Quality Coax. (Messi Hyperflex 5 / Ultraflex 7)  [[https://www.hamradio.co.uk/messi-and-paoloni-hyperflex-5-pd-6679|ML&S]]
  
-Whole thing can be built for less than £20 if you shop around / scavenge a bit more.+Whole thing can be built for less than ~£25. Less if you shop around / scavenge a bit more.
antennas/qfh.1713299544.txt.gz · Last modified: 2024/04/16 20:32 by 2m0vsr