PlaneHeli

I have a Futaba R137HP Rx which is faulty.

I thought Id use a Futaba R146iP Rx id bought for a small electric plane.

The specs for the range of these Rxs are the same from the info I have found (approx 300 meters).

The smaller R146iP Rx has a much shorter antenna than the larger R137HP Rx.

I always thought the length of the antenna was required to be a certain length based on the frequency.

They are both 40 Mhz PCM Rxs. Why is the R146iP Rxs antenna shorter.

Would the range be the same on these two Rxs.

I would like to use the R146iP on a .40 glow plane. Just a little concerned about its range.

Rodney

You will find most RC receivers (other than park flyers) have an antenna that is 39 to 41 inches long regardless of frequency whether they be 75, 72, 50, 53, 27 etc. MHz. This is because each receiver antenna is base loaded and tuned to work with that length of antenna by adjustment of the LC circuits. Many park flyers do have a shorter antenna but are also base loaded and also have a shorter range due to decreased capture area and different electronic design. Check out www.rc-cam.com for some good info on effects of different antenna lengths. The full story is quite complicated and length alone does not tell the full story.

PlaneHeli

Rodney,

Thanks for the reply.

I cannot find the info on the link you provided. Cannot search without signing up.

The fact that the R146iP Rx antenna is shorter than the normal Rx worries me. As you say, shorter Antenna often means lesser range. Why have a shorter antenna than the normal 39 - 41 inch antenna you mention.

Are others using the Futaba R146iP Rx in 40 or larger sized glow planes.