more or less or use while on low power mode. Only if the excess gets in the way, the 17 Ft length was the usual length of a run from a dashboard mounted radio to the roof or trunk-lid mounted antennas.New Genuine OEM Motorola Part HKN9407A Fused Power Cord Adapter Motorola OEM Mobile Power Cord Assembly For use with mobile radios operating at 25 watts. You should not ever have to "trim" the 17 ft coax line that comes with the kit to tune the antenna system. That kept the whips in a practical length across the wide freq ranges. Low VHF from 25 to 50 mHz used a number of different base coils with more turns of coil to work on lower freq segments of the range. Many 5/8 wave base coils are like an "autotransformer" that has a tapped coil to cancel X and match Z to a 50 Ohm radio. The base for those has a few turns of coil to cancel any Xc there. The taller UHF antennas with a center phasing device are two 5/8 wave colinear, in phase design.
There are the 5/8 wave antennas with base coils that fit on the basic NMO bases that are simply a threaded attachment and a coax connection. The later version for 800+ had smaller center contacts and more Teflon and other higher quality insulation. On VHF, UHF and then 800-900 MHz systems. I used those antennas for Commercial and public safety radio systems for many decades.
Need to reference my antenna book as I kinda forgot a couple things here on the antenna length formula, but if someone can quickly jog my memory on which direction I need to go (longer vs shorter) when I get a analyzer or just a vhf slug for my bird meter so I can do these measurements id highly appreciate it. The antennas look the same except for a slight difference in color of the base.ģ. No clue what the A and B versions differ on, the model codes are the same except for the last digit being "a" and "b". Are these antennas base loaded with a coil or whatever at the base that makes it where I cant place a longer whip to make a 5/8 wave 2m antenna? I have some spare whips, and I do like the spring base of these antennas in case I drive under something low it doesn't bend the antenna like the larsen brand versions I own.Ģ. Love my rig expert, but didn't have the money at the time to get the uhf/vhf version along with hf.ġ. No antenna anyalizer for vhf, but I'm gonna try to borrow one from someone, I just want to get a few things squared away prior to borrowing one from a local ham. There chart of vehicle antennas list different model numbers for 1/4 wave at vhf frequencies, so i'm trying to figure out what is different about these compaired to the 1/4 wave versions. I'll post a few pics from my phone here on what I have. my assumption they are just a recieving antenna as Idk how they could have such broad bandness with good swr. The little info I have about these two antenna kits I bought are that they say they are tuned for 136-172 vhf and need to fine tuning. I got a couple motorola vhf antenna kits (nmo mounting kit/coax/antenna/pl-259 for hard mounting on a vehicle) that are new old stock from hamvention a couple years ago and I've just got a couple questions for anyone that can help me please.
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