ballgunner

My Feedback: (1)

Just got a Dumas boat antenna. The Tower spec sheet on their web said it came with instructions. Bah. It does have a picture of how to install the thing but I could have figured that out by myself. I have already determined a better mounting than they show. My question is; should I shorten the length of the RX antenna by the length of the solid wire that is above the deck so that the total length of the antenna is 39 -40" overall. I am electronically challenged at any point beyond soldering and flipping the switches. Any help will be sincerely appreciated. TNX in advance.

Villy

I am assuming that you are going to clip the antenna from the receiver short, and then connect the end to the inside connection of the boat antenna.

If that is the case, then the total length of everything (including the solid wire) from the receiver to the end of the antenna should be the same as the original antenna length (~ 39+ ").

In otherwords, yes it should be shortened by almost the length of the solid wire (left longer by the amount required to make your 2 connections)

Villy

(I am assuming that the boat deck is non-metallic)

Geistware

My Feedback: (16)

Antennae length is 1 meter.
THis is 39.36996 inches

Rodney

If the wire section on theboat is just that, a straight piece of wire, the above advice is correct. However, some antennas that have been put on boats (also on some planes) have a coil (this might look like a molded resistor) at the end of the wire nearest the receiver. This is just a choke that electically tricks the reciever into thinking the antenna is longer than it really is. If that is so, you only want about 3 or 4 inches of wire between the rigid antenna and the receiver.

Geistware

My Feedback: (16)

THe above is true.
If you have some kind of whip or pigtail antennae, then it doesn't have to be very long.

mr.rc-cam

If you are installing this on a USA operated R/C boat or car, then you are using a 75Mhz system, not 72Mhz. Total antenna length will probably not be the traditional 39" to 42" as used on model aircraft. The 75Mhz Rx's are substantially base loaded -- total required aerial length is often only 19" to 21". Futaba FAQ: http://www.futaba-rc.com/faq/service-faq.html#q235

It is only coincidental that the typical length is nearly a perfect 1/4 wave for North American 72Mhz Rx's. Generally speaking, model R/C Rx do NOT follow the standard convention for 1/4 wave antenna lengths. Regardless of freq (35Mhz, 40Mhz, 50Mhz, 72Mhz, 75Mhz) the antenna lengths are shortened for our convenience and use compatible impedance matching techniques in the Rx's front end.

ballgunner

My Feedback: (1)

Thanks to all who replied to my Q, RE boat antenna. I should be able to make it work now.