Model Boat Mayhem

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: inertia on June 17, 2016, 11:20:57 am

Title: Length of receiver aerial wire
Post by: inertia on June 17, 2016, 11:20:57 am

A quick question. I have three of these receivers but have shortened all of the aerials to connect to whip antennae. I've calculated the probable length of the full-length wire (as supplied) as 92cm, but can anyone who has one just confirm this for me? Nominal frequency is 40.675MHz.
I begin to mistrust my maths these days!
Dave M

Title: Re: Length of receiver aerial wire
Post by: C-3PO on June 17, 2016, 11:46:13 am

92cm would be 1/8th of the wavelength @ 40.675Mhz

Title: Re: Length of receiver aerial wire
Post by: inertia on June 17, 2016, 12:16:54 pm

Yep - that's what I got. 10/10?
Seems a bit on the lengthy side but I seem to recall that they were originally.
Any confirmation of our calculation from owners?
Dave M

Title: Re: Length of receiver aerial wire
Post by: C-3PO on June 17, 2016, 12:23:53 pm

Dave,

Hitec HP-2RNB - 104.5cm tip to case

Robbe Futaba - FP -R118F 98cm tip to case

Just to confuse things!

Title: Re: Length of receiver aerial wire
Post by: inertia on June 17, 2016, 12:38:39 pm

Yeah - many thanks for that, C3P0...  :o

I reckon 92cm will do, don't you? After all, we don't need out-of-sight range for our particular toys, innit?

Ta, m'duck.

Dave M

Title: Re: Length of receiver aerial wire
Post by: unbuiltnautilus on June 17, 2016, 03:58:42 pm

I have two 40mhz HFS-04MI+ Rxs in my grubby hands, 945mm and 965mm respectively, tip to casing.

Title: Re: Length of receiver aerial wire
Post by: roycv on June 17, 2016, 05:08:14 pm

Hi all, as long as there is enough of it, it does not seem to matter.  I usually cut my Rx aerials to about 6 inches long and fit a gold plated connector, then the rest of the aerial is incorporated into the model.  If I can, I have a soldered wire connected to a mast, part of the mast I make of brass tube with some wire and a matching connector at the end.  So there is usually about 3 feet of it, which certainly works for me.
Then if I need to change a Rx I can unplug it.
regards Roy

Title: Re: Length of receiver aerial wire
Post by: inertia on June 17, 2016, 06:33:25 pm

Thanks, Roy, but I already did all of that. The current situation is reversing it so that I can offer the receivers for sale. I've settled at 92cm.
DM

Title: Re: Length of receiver aerial wire
Post by: roycv on June 17, 2016, 11:09:41 pm

Sorry DM did not pick that up from your Initial post., when you are finished will you see the join?
regards Roy

Title: Re: Length of receiver aerial wire
Post by: inertia on June 17, 2016, 11:18:13 pm

How dare you, sir!!  >>:-(

Nah - I took 'em out of their cases first and used all new wire, so there ain't no join except the one to the PCB........but let's keep that a secret, eh?  %)

DM