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Author Topic: Larson LA/JM 150  (Read 2613 times)
KB1UZD
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Posts: 3




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« on: December 21, 2012, 04:32:56 PM »

I picked up a few antennas free, one of which is a Larson LA/JM 150. Does anyone have any info about these units? I hope to use it on a Yaesu FT 2900. The whip is 48"".  It appears similar to the newer Larson 150 models for a 5/8 wave 2 M.
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W9GB
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« Reply #1 on: December 22, 2012, 09:25:50 AM »

Pulse Electronics acquired the Larsen Antenna company/brand name several years ago.
This is the Larsen/Pulse web page for products, repair parts, and support
http://www.pulseelectronics.com/products/antennas

Larsen made a number of mobile vehicle antennas from 1/4-wave, to 1/2-wave and 5/8-wave designs.  
The mountings varied (NMO, UHF, 5/16-24 or Larsen Mount, BNC, thru-glass, integrated magnetic mount) depending on model.
NARROW your search, by determining the Mount used.  
A 48" whip is common for Larsen VHF Kul-rod 5/8-wave (low profile) loading coil.

I had to DIG through old QST archives to find the JM mount.
It was mentioned as New Product in April 1976 QST, page 33.

The JM-mount only requires a 3/8" hole in vehicle body and uses the 5/16-24 stud (later called, LM for Larsen Mount) for mounting.
The LA/JM 150 was offered for fast installations in one-sided (blind) vehicle installations.
The 1970s LA/JM was later known as the Larsen Mount - LM

Larsen Mobile Antenna catalog (PDF), before mergers, 111 pages.
DOWNLOAD and SAVE this copy -- getting hard to find and required for Larsen antenna scavengers!
http://www.scoden.com/pdf/mobile.pdf

TESSCO sells and support these non-Motorola (NMO) style mounts in permanent and magnetic versions.
https://www.tessco.com/products/productHierarchy.do?subtabId=33094

The LM150 models (B for Black whip; C for chrome whip; and U for unplated stainless steel whip versions)
that used the Larsen 5/16-24 stud for mounting.
 The NMO150 looks identical, BUT uses the NMO mount!!
http://productfinder.pulseeng.com/products/datasheets/Mobile%20136%20to%20174%20MHz.pdf

Larsen Antenna Mounts -- the LMB is the 5/16-24 THDS
http://productfinder.pulseeng.com/products/datasheets/MOUNTS.pdf

Product Catalog of current offerings
http://www.pulseelectronics.com/download/3802/antennas_g00302pdf
« Last Edit: December 22, 2012, 10:19:43 AM by W9GB » Logged
KB1UZD
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Posts: 3




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« Reply #2 on: December 22, 2012, 12:09:26 PM »

Thanks for the info. I  had checked out the Pulse/Larson web site to see if there were any matches. I was not sure ,and did not want to mess up anything blundering around.
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W9GB
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« Reply #3 on: December 22, 2012, 01:34:19 PM »

You should be good to go,
following the Larsen LM150 documents and using LM (5/16-24) style mounts.
http://productfinder.pulseeng.com/products/datasheets/MOUNTS.pdf

Ham Radio Outlet (HRO) carry Larsen mobile antenna parts
http://www.hamradio.com/pdf/hrocat8.pdf

Replacement whips, W490(B) with 0.100 taper in stainless or black, can be ordered for that LM150 coil - when required.
http://www.repeater-builder.com/antenna/pdf/larsen-mobile-antenna-mounting-and-designations.pdf
« Last Edit: December 22, 2012, 01:48:45 PM by W9GB » Logged
KB1UZD
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Posts: 3




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« Reply #4 on: December 23, 2012, 06:56:40 AM »

Thanks for all the info. I have several different magnetic mounts that I obtained. Most with 220mhz whips and coils. I can match up specs with the info you sent.
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