Hi Folks,
Just got a couple of Low Band MT-1000s that are on 6m.
They seem to work great, but was wondering if the antenna is
the correct length.
What is the stock length of the antenna that'll do 52 mHz?
Thanks,
Tim
Length of stock Low Band MT-1000 antenna?
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Re: Length of stock Low Band MT-1000 antenna?
Tim,
Take a look at the cutting chart at this link:
http://www.repeater-builder.com/motorol ... -guide.pdf
It will tell you what frequency a low-band HT antenna is cut to. It stops at 50 mHz but you should be able to extrapolate from that. Note that for some reason it tells you not to use the chart to actually cut an antenna.
Fred
Take a look at the cutting chart at this link:
http://www.repeater-builder.com/motorol ... -guide.pdf
It will tell you what frequency a low-band HT antenna is cut to. It stops at 50 mHz but you should be able to extrapolate from that. Note that for some reason it tells you not to use the chart to actually cut an antenna.
Fred
Re: Length of stock Low Band MT-1000 antenna?
Be aware that the dimension in that chart is what you cut off of the uncut antenna.
Measurements that I made on several P200's and Mt1000 using a HP8753 Network Analyzer, holding the radio in my hand, with a pigtail coax connector at the radio PCB end showed around 6.25 inches overall length for mainly tx below 52.525 MHz and if you were using the radio for TX above ~52.8 then 6 1/8 inch is a perfect number.
HT antenna measurements need to really be made in an anechoic chamber with the radio as a ground plane, and a hand simulator which adds body capacitance, to be meaningful or you could also resort to field strength measurements which I did as a backup using a station 20 miles away on 52.06 MHz which was the center of my TX range.
If you cut your antenna to 6 1/4 inches from top to the bottom of the connector end then you should be fine across the majority of the frequencies used for TX, as high as 52.525 and as low as 51.3 MHz.
You wont see any measurable difference on the RX end between 6 and 6 1/2 inches.
Mike
Measurements that I made on several P200's and Mt1000 using a HP8753 Network Analyzer, holding the radio in my hand, with a pigtail coax connector at the radio PCB end showed around 6.25 inches overall length for mainly tx below 52.525 MHz and if you were using the radio for TX above ~52.8 then 6 1/8 inch is a perfect number.
HT antenna measurements need to really be made in an anechoic chamber with the radio as a ground plane, and a hand simulator which adds body capacitance, to be meaningful or you could also resort to field strength measurements which I did as a backup using a station 20 miles away on 52.06 MHz which was the center of my TX range.
If you cut your antenna to 6 1/4 inches from top to the bottom of the connector end then you should be fine across the majority of the frequencies used for TX, as high as 52.525 and as low as 51.3 MHz.
You wont see any measurable difference on the RX end between 6 and 6 1/2 inches.
Mike
Re: Length of stock Low Band MT-1000 antenna?
Actually, I wasn't totally clear in my post.
I meant to say that the spot-check chart isn't supposed to be used to cut the antenna. Mike is correct that the chart with the graph(s) is for working with the new antenna.
Fred
I meant to say that the spot-check chart isn't supposed to be used to cut the antenna. Mike is correct that the chart with the graph(s) is for working with the new antenna.
Fred
Re: Length of stock Low Band MT-1000 antenna?
It throws everyone off, it's a Motorola Bass Akwards document.
The first time I saw it I had recently tuned a bunch of 6 meter antennas on my network analyzer and then someone posted the document and of course I measured my antennas and said WTF ?
After reading it several times I saw that the dimensions were what to cut off of a stock 11 9/16 inch whip and nothing about the final cut length.
If I ever find the time I may make up a correct length document.
The first time I saw it I had recently tuned a bunch of 6 meter antennas on my network analyzer and then someone posted the document and of course I measured my antennas and said WTF ?
After reading it several times I saw that the dimensions were what to cut off of a stock 11 9/16 inch whip and nothing about the final cut length.
If I ever find the time I may make up a correct length document.
Re: Length of stock Low Band MT-1000 antenna?
Great Idea...mike m wrote: If I ever find the time I may make up a correct Low Band portable antenna length document.