How to adjust and tune RX and TX Power of Vhf mobile Radios

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saathi417
Posts: 2
Joined: Wed Jun 25, 2008 4:49 pm

How to adjust and tune RX and TX Power of Vhf mobile Radios

Post by saathi417 » Tue Jul 15, 2008 3:19 pm

Hello to All Friends in This Group

Can you Please advice me How to adjust and tune RX and TX Power of Vhf mobile Radios Step by Step Instructions to get Full Range I have very Week Range Dont Know How to Properly Tune . Which is proper tool to Check the Radio and Antenna Power

I have Icom F121 VHF Installed in my Pickup and Truck. I Have Problems as described under. Before Icom i Used to Have KENWOODS VHF.

I mostly use 166.*** and 167*** vhf frequencies. Can You Please Advice me How to Tune Whip Antenna. Currently i have 30 inch whip without spring.

I have a WATT Meter (older Style with watt, call, swr tester 5 ,50, 500) . Watt Meter shows 25 watts Approx while transmitting on 166.***, 167.*** Frequency. With 35 inch whip i got 18 watt of power while Transmitting.

Another thing Radio is Giving more than 45 Watt on 151.6** and 154.*** Frequncies. (I love if it could be on 166.***)

These radios are Brand New I got 7 Brand New and 1 Slightly Used.. Tried all These Radios But Same Result Little Bit
Difference. These Radios Have 50 Watt Output As Described in Manual.

Can you Please Advice Me A Right Direction what i am doing Wrong

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n9gik
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Posts: 98
Joined: Sun Aug 01, 2004 12:41 am
Location: SE IL

Re: How to adjust and tune RX and TX Power of Vhf mobile Radios

Post by n9gik » Thu Jul 17, 2008 11:55 pm

My first recommendation would be to find a good local dealer, or at the very least someone knowledgeable with VHF antenna tuning. Based on the questions you are asking your technical experience is not all it could be.

I would question the meter you have. Most of the economically priced power meters I have looked at did not have a frequency range covering 160+ MHz. I ended up buying a Drake WV-4
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many years ago because most meters at the time did not cover our business freq (153 area) unless you spent real money. Having a good meter or antenna analyzer is critical. Consider getting something like the MFJ-209 (see http://www.mfjenterprises.com/Product.p ... id=MFJ-209 ) or MFJ-220 Image to help you in antenna tuning.
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There are others, but these are ones I am familiar with and reasonably priced. Nothing is going to work right until you get the antenna tuned to the frequency you are operating on. I suspect getting an antenna to tune 151 to 167 is going to be difficult. Your radios are probably sensing too much power being reflected back to the radio and shutting down their power output as a protective measure.
I don't know much about 2-way radios but I'm over 50 and can't remember not having one around. Everything from Buddy and Citi-fone to Icom and Kenwood.

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