70cm Antenna

[Jaymom]

I just ordered a Yaesu FT-7900R 2M & 70cm transceiver. I have a J-Pole antenna for 2M and I'm not sure what to use for a 70cm antenna. Would it be possible to use the J-Pole? If not what do you suggest?

Have a blessed day,
Harold

 

[office888]

I just ordered a Yaesu FT-7900R 2M & 70cm transceiver. I have a J-Pole antenna for 2M and I'm not sure what to use for a 70cm antenna. Would it be possible to use the J-Pole? If not what do you suggest?

Have a blessed day,
Harold

You need a dual-band antenna.

They do make dual-band J-poles, however, if yours is not one of them, then it will obviously not work.

It all depends what you want to do. Higher gain antennas are taller, and produce a low angle of radiation. To work well, they must be mounted 30+ ft above ground. Also, be sure to keep your coaxial cable runs short, and to use a high-quality low-loss coaxial cable such as RG8U, LMR400, or Belden 9913.

Obviously if you intend to work satellites, you don't want a low angle of radiation, you want more of a circular pattern.

 

[Jaymom]

I wish I had the room to errect numerous antenna's. Now to find something to use on 70cm.

Thanks,

Harold

 

[W5LZ]

Believe it or not, that 2 meter 'J'-pole will work 70 cm just fine. Expect something close to a 2:1 SWR, but that's not all that uncommon and won't harm that Yaesu at all.
- 'Doc

 

[Beetle]

Take the approximate center of 2 meters (146 MHz) and multiply it by 3. I get 438, which is pretty close to the 70 cm frequency. If you make a 1/4 wavelength ground plane for 2M (~19 inches long), it will be very close to 3/4 wavelength for 70 cm., like Doc said.

Odd multiples of 1/4 wavelength. Good thing to keep in mind for antenna work.

 

[Jaymom]

I'm experimenting Beetle. Love this hobby. Found a 70m J-Pole also.

Doc, I was told the same thing at our last club meeting. Waiting for my Yaesu to get here now.

Many thanks,
Harold

 

[Beetle]

I'm experimenting Beetle. Love this hobby. Found a 70m J-Pole also.

Doc, I was told the same thing at our last club meeting. Waiting for my Yaesu to get here now.

Many thanks,
Harold

A 70 meter J-Pole? Wow! About 230 feet high.

...or was that 70cm?

 

[Jaymom]

Yep, ya got me on that one. :headbang