VHF Low question??

[scanjunkie]

Hi All,
Will an antenna designed for the CB range, or an antenna designed for the 6 meter range work well on the 33.00MHz range??
Thanks for your help!
Mark

 

[N_Jay]

Hi All,
Will an antenna designed for the CB range, or an antenna designed for the 6 meter range work well on the 33.00MHz range??
Thanks for your help!
Mark

CB will be a bit too long, but should work OK.

6 meter will be a good bit too short, and will not work as well.

 

[W4KRR]

CB frequencies are 27 MHz, so a CB antenna should work pretty well for 33 MHz, probably better than a 6 meter antenna, which is for 50-54 MHz. But the higher you go above 33 MHz, the worse the CB antenna will perform, but it should do pretty well in the entire VHF low band range.

 

[scanjunkie]

Great!! Thank you very much for your help!!

Mark

 

[DaveH]

I used an old CB quarter-wave groundplane antenna for years and it worked great at the low end of 30-50MHz (also around 33MHz).It seemed to work on the high end OK as well. Too bad most of the interesting local activity is gone now (sigh).

Dave

 

[ReceiverBeaver]

Hey dude...again with that [work well?] thing. It depends if you're going to want to transmit or listen only. Listen only? yeah you're in like flynn. But to transmit the any antenna is going to have to be tuned for resonance or at least an SWR of below 2:1 or your tx final section will suffer. Meaning reduced output and the possbility of burning out the final transistors.

The Navy did a study awhile back and determined that a simple length of wire 9 feet long received all HF frequencies more or less just about as well in most circumstances than having a precision resonant antenna. Again talking about only RECEIVING.

Never forget that you can make an antenna out of ANYTHING that will conduct electricity and that you have considerably much more leeway in what you hook up if you are only needing to receive. Transmitting ALWAYS requires having an antenna device which is tuned for the operating frequency, or close enough to it, to achieve a low-permissable SWR, wether the antenna itself is resonant (always preferrable) or you are obtaining the tuning match for your transmitter by using an antenna tuner or similar matching device.

 

[scanjunkie]

Great info...thank you all for your input!!

Happy Holidays!!
Mark

 

[N_Jay]

. .
The Navy did a study awhile back and determined that a simple length of wire 9 feet long received all HF frequencies more or less just about as well in most circumstances than having a precision resonant antenna. Again talking about only RECEIVING.

. . . .

Those wacky Navy guys!!!!! :twisted: :twisted: :twisted:

Now show a link. :evil:

 

[nyscan00]

I use a external cb whip antenna and it works excellent on lowband. I listen from 46.00 to 49.00mhz ...reception in great!

should work fine for you too....

 

[ReceiverBeaver]

Hi Njay,

Sorry don't remember. I think I read it in a Monitoring Times magazine a number of years ago.

 

[OutPost]

42 to 49 mhz

Just for kicks, I attached my HF Dipole antenna to my scanner and low FM 42 to 49 mhz worked better than my ground plane. I have a homemade 90 foot 45'/45' horizontal dipole, using 14 gauge (coated) copper wire with a DirecWay coax (high grade but no specification on the cable) attached to a pig tail connector, and so forth.....

Also 27.185 AM reception was excellent too!

 

[N_Jay]

Re: 42 to 49 mhz

Just for kicks, I attached my HF Dipole antenna to my scanner and low FM 42 to 49 mhz worked better than my ground plane. I have a homemade 90 foot 45'/45' horizontal dipole, using 14 gauge (coated) copper wire with a DirecWay coax (high grade but no specification on the cable) attached to a pig tail connector, and so forth.....

Also 27.185 AM reception was excellent too!

An HF dipole is almost a longwire antenna at 45 MHz.

 

[N_Jay]

Hi Njay,

Sorry don't remember. I think I read it in a Monitoring Times magazine a number of years ago.

Well, Statements like that make no sense.
That is why I commented.

The question I would have is; were they evaluating a resonant antenna OF THE SAME SIZE, or of the nateral size to be resonant at the desired frequency.

Much would depend on the impeadance and design of the transmission line system to make any compairison valid.

 

[KD4UXQ]

Vertical base CB antennas often have a shunt fed coil at the base. If the CB antenna has a shunt fed coil, it may work if you cut enough of it off, but it would be hard to know how much. I once tried to use a shunt fed base antenna for 42 MHz without any pruning and it did not work very well at all. The coil limits the bandwidth. If the CB antenna does not have a shunt fed coil, it would probably work pretty well at 33 MHz without any pruning. Would'nt hurt to give it a try if you already have one. A homemade 1/4 wave dipole would probably work best if cut the right length for 33MHz. Unfortunately the elements would be 7 feet long each, but maybe you could put the dipole assembly inside a 15 foot piece of PVC for support. 234/frequency = 1/4 wave element in feet