bglatour001
Member
Has anyone ever used a K40 antenna on 2m? Is it even possible to tune it to a center frequency of 146.00? And if it is possible, what was the performance like?
2m Antenna Question
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fineshot1
Member
I suppose many things are possible, but is it worth the trouble?
Probably not. The K40 is designed and tuned for 27Mhz not 146Mhz.
If its possible you would have to take it apart and completely change the
size and number of turns in the matching coil and cut the whip down in
size and perhaps change a capacitor.
When there are so many cheap 2mtr antennas already on the market
why would one need to do this?
bglatour001
Member
It was just to solve a discussion I had with a friend of mine. I kinda figured as much but he was insisting that it could be used. As for cheap antennas, there's nothing available locally for ham gear. One little section in the local electronics store that deals in commercial gear.
fineshot1
Member
Many things can be used (temporarily) on 2mtrs. Even a coat hanger comes to mind considering
that about 19" of a plane whip is a 1/4 wave on the 2mtr band.
Most of the vhf/uhf rigs designed and made today have power fold back designed into them
so if the antenna does not provide a good match the radio senses the higher swr and lowers
the power output automagicly. But this still does not prevent the final amp brick to heat up,
and as we all know heat is the number one enemy of electronics.
If he uses the K40 warn him not to be long winded in his key ups so as to give the amp in
his radio time to bleed off heat and wish him good luck.
RadioDaze
Member
Using a K40 on 2 meters is like using kindergarten scissors in a college art class.
N8IAA
Member
The fact that the whip would be so short, the bandwidth would be extremely narrow, and low power would need to be used. The question would be, WHY
Larry
What kind of licensing test do you take in Canada? OY, such a question you ask!
WHY would you even ask a question like this? On second thought, go ahead and use it because two meter radios are pretty cheap to replace anyway.
n9zas
You clearly have internet access. Do you get postal delivery service?
Some older (circa 1974) CB mobile mag mount antennas can be opened and the coil modified to turn it into a 5/8 wave 2M antenna and retuned for a near 1:1 match. Lots of info on other forums, e.g. QRZ, eham, and magazine articles over the years. Opening the coil is probably going to allow water to seep in when you reclose it and go mobile. This will destroy whatever tuning and operational efficiency you so carefully built. Appears that recent manufacture CB antennas are not easily modifiable.
You can do this easily for the 6 meter band,but NOT 144-148 mhz. Try a 102 or 108" whip and trim it down,but the RIGHT antenna to begin with would be easier!
n9zas
N8IAA
Member
Do they sell 1/4 wave VHF antennas? Because, if they do, the whip should be at the low end of 140MHz. Cut the antenna to 146MHz and be happy
Larry
Of course they sell quarter wave antennas, you're another one giving me agita!
bglatour001
Member
Actually, my local shop only has 5/8 whips, NMO only, no mag mounts. It's pretty lame in the north for finding ham gear.
N8IAA
Member
reedeb
Member
A. Find another shop as they aren't doing you a service.
B. Go online and find a company [online store] that will deliver to you. You WILL have to pay wih a card.
Find the correct antenna, no trying to modify a CB ant. into what you need.
bglatour001
Member
A. I live 150 kms from nowhere, not that easy to find another shop.
B. The question was asked to settle a discussion with a non-ham. (See post #3 in this thread)
and
C. I personally BUILD my antennae, much better than anything you can buy.
B. The question was asked to settle a discussion with a non-ham. (See post #3 in this thread)
and
C. I personally BUILD my antennae, much better than anything you can buy.
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