Author Topic: Antenna wokshop  (Read 14167 times)

0 Members and 2 Guests are viewing this topic.

Offline Wrightwood

  • Administrator
  • Raccoon
  • *****
  • Posts: Plenty of Posts!
  • Wildlife Gateway
Antenna wokshop
« on: Mar 22, 07, 05:44:25 PM »
In the March '07 issue of the ARRL QST magazine they revisited making a portable roll-up J-pole antenna for 2 meter/70 cm.

With a few dollars worth of parts you can construct a portable roll-up antenna that's perfect for backpacking or emergency use.

Maybe we should hold a few hour workshop and give everyone a chance to build one of these.
Wrightwood Forum is the first & most dependable local social media outlet

clint

  • Guest
Antenna wokshop
« Reply #1 on: Mar 22, 07, 06:02:44 PM »
I would love to do that John, but we should a cut chart for 220 and build both. I can pre make coax with nice crimped on BNCs and everyony can create their own antennas and learn to solder.

Offline Wrightwood

  • Administrator
  • Raccoon
  • *****
  • Posts: Plenty of Posts!
  • Wildlife Gateway
Antenna wokshop
« Reply #2 on: Mar 22, 07, 06:26:48 PM »
All those interested need to speak up so we can get an idea on the interest.

We'd spend a few hours, maybe $10 or so each for supplies and build a couple of antennas for backpacking or emergency use.

Offline RobertW

  • Moderator
  • Raccoon
  • *****
  • Posts: Plenty of Posts!
  • Clear Skies!
Antenna wokshop
« Reply #3 on: Mar 22, 07, 07:05:24 PM »
All those interested need to speak up so we can get an idea on the interest.

We'd spend a few hours, maybe $10 or so each for supplies and build a couple of antennas for backpacking or emergency use.


I'm interested...

Offline RennMan

  • Moderator
  • Raccoon
  • *****
  • Posts: 729
  • N4MAN
Antenna wokshop
« Reply #4 on: Mar 22, 07, 07:13:20 PM »
I was just reading that article a couple of weeks ago, one of the few technical ones in QST that doesn't scare me with theory that I'm weak on, even on my best day.

I'd like to get in on the portable J-Pole class too.  Count me in!

kew

  • Guest
Antenna wokshop
« Reply #5 on: Mar 22, 07, 08:05:12 PM »
All those interested need to speak up so we can get an idea on the interest.

We'd spend a few hours, maybe $10 or so each for supplies and build a couple of antennas for backpacking or emergency use.


I'm in. When do we start?

Offline Wrightwood

  • Administrator
  • Raccoon
  • *****
  • Posts: Plenty of Posts!
  • Wildlife Gateway
Antenna wokshop
« Reply #6 on: Mar 22, 07, 09:11:47 PM »
RobertW we are talking about making a flexible J-pole that can be rolled and put in your backpack. It can be hung out a window at home or used with a piece of fishing line thrown over a branch on a tree.

Here's the inexpensive flexible type we'd be making:
http://www.kb3kai.com/j-pole.php#photos

When I get a chance I'll scan the QST magazine article and post it. It provides all dimensions needed for 2m/70cm. Clint suggestion was to also make one for use on 220 by changing the cut dimensions.

With the price of copper tubing that style of j-pole might be out of the range of most for a quick project and is also difficult to get in and out of a backpack  ;)

Here's another copper type: http://www.kb9vbr.com/kb9vbr_jpole_plans.pdf


Offline Wrightwood

  • Administrator
  • Raccoon
  • *****
  • Posts: Plenty of Posts!
  • Wildlife Gateway
Re: Antenna wokshop
« Reply #7 on: Mar 28, 07, 12:07:54 AM »
Here's the one from the QST Magazine that we were talking about:

http://www.wrightwoodcalif.com/ham/FlexJpoleAntenna.pdf

KWBoy

  • Guest
Re: Antenna wokshop
« Reply #8 on: Mar 28, 07, 12:10:10 AM »
Let me know if you do have one and sign me up!

kew

  • Guest
Re: Antenna wokshop
« Reply #9 on: Apr 02, 07, 01:08:59 AM »
What kind of gain would you expect from J-Pole antenna?

Offline Toolman

  • Raccoon
  • *****
  • Posts: 874
  • You can't fix stupid
Re: Antenna wokshop
« Reply #10 on: Apr 02, 07, 02:35:50 AM »
What kind of gain would you expect from J-Pole antenna?

 That depends Ken,
A typical J-pole can have upwards to 6 DBI of gain depending on it's wave length and how it's constructed. BTW, you can buy a roll up J-Pole from MFJ for about 19.95 but it's allways good to learn the mechanics of antenna building. The roll up dipole for 2mtrs. will have maybe 3dbi of gain which is still better than the rubber duck which is just resonate at 2bi which means no gain.
The MFJ roll up dipole uses 300ohm twin lead typical to the good old TV antenna lead. I'll let you guys figure out how to match it... ;)
 
 After long thought and surveying of my property, I decided to put up a Delta Loop for HF. I've been on the receiving end of many Delta Loops and they play very well. Much better than a typical Dipole because of the pattern they create and gain factor over a Dipole. The problem is they are big and mine figures out to be about 287' long. They are also multiple band and it's the only solution for me until I can get a Yagi up. The Delta Loop requires a good antenna tuner such as any dipole will as well. I made the Balun for it this weekend and have all the hardware assembled and the total cost is about 35 bucks. Not bad for an efficient HF antenna eh? Just got to get up in them thar trees to string it. :o

Offline spellbinder

  • Scrub Jay
  • ***
  • Posts: 182
Re: Antenna wokshop
« Reply #11 on: Apr 04, 07, 04:06:29 AM »
Sign me up as well.




KI6CXD