Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Match on 75M Mobile whip




 
The AM Forum
November 14, 2018, 09:06:26 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Match on 75M Mobile whip  (Read 1362 times)
0 Members and 1 Guest are viewing this topic.
WU2D
Contributing
Member
*
Offline Offline

Posts: 1677


CW is just a narrower version of AM


« on: August 05, 2011, 05:44:23 PM »

Well I finally got a more conventional mobile whip on the air. My minihustler mag mount was not a great situation even though it did work. The good old MO-2 mast is slick and the fold over feature is nice.

This should be a bit more efficient. One thing I did was attempt a shunt match and I can say it worked out better than I imagined. It is simply 13 turns of # 12 enamelled on a 1 1/2 inch PVC form; bottom grounded and coax tapped up 5 turns. The top of the coil feeds the bottom of the mobile whip. This match not only gives a DC ground (very nice for noise and safety), but it takes a modest 1.7:1 match without the device and makes it essentially a perfect match, and without disturbing the resonant frequency too much. I have a small capacity hat that I slip on to reach 3570 for CW. By pulling the whip all the way out I can not quite hit the bottom of the band which is normal for the 75M resonator. With the capacity hat which is simply six 4 inch wires off a brass spoke hub.

On the road tomorrow AM.

Mike WU2D


* HUSTLER_MATCH.jpg (437.78 KB, 3072x1728 - viewed 262 times.)

* ClassicHustlerFoldoverMO2.jpg (599.25 KB, 3072x1728 - viewed 186 times.)

* Classic_Hustler_75M.jpg (396.97 KB, 2130x1494 - viewed 207 times.)
Logged

These are the good old days of AM
AJ1G
Contributing
Member
*
Offline Offline

Posts: 987


« Reply #1 on: August 05, 2011, 05:53:11 PM »

Looks good Mike - does it bonk on the trunk from the spring?   Looks like you're going without any guy lines..makes for a clean look.
Logged

Chris, AJ1G
Stonington, CT
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2180


IN A TRIODE NO ONE CAN HEAR YOU SCREEN


WWW
« Reply #2 on: August 05, 2011, 06:38:36 PM »

Good antenna idea.

Say, what is all that green stuff on the ground? Wink

73DesertDG
Logged

Just pacing the Farady cage...
WU2D
Contributing
Member
*
Offline Offline

Posts: 1677


CW is just a narrower version of AM


« Reply #3 on: August 05, 2011, 07:04:18 PM »

I will definitely put some big monofillament from the rear seatbelt guides from each side out the door to the whip and we will see how it bonks the car - good prophesy on that; I may slip some foam pipe around the thing at the likely contact point. So it may not look so clean by the time I am done with the trip!

Mike WU2D
Logged

These are the good old days of AM
WU2D
Contributing
Member
*
Offline Offline

Posts: 1677


CW is just a narrower version of AM


« Reply #4 on: August 08, 2011, 06:29:08 AM »

The Solar flare did me in on the way up but coming home Sunday, the new antenna did a great job. The Shunt match worked perfectly right across the band. All you have to do is resonate the whip up top. AJ1G says that to get optimal better performance, I need to raise the feed to at least the trunk level or up about 1 ft. I will ponder this.

Mike WU2D
Logged

These are the good old days of AM
WA1GFZ
Member

Offline Offline

Posts: 11152



« Reply #5 on: August 08, 2011, 09:54:59 AM »

gee I just did the same type of match on 600M Sunday...but the coil was bigger and the antenna 200 foot inverted U
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.047 seconds with 18 queries.