Jim,
I know I've not been getting much exercise with Lockdown and all, but I haven't put on THAT MUCH weight😁
Still hovering around 90kg😊
Cheers, Doug 😎

No theory Graham, simple physics 😉
λ=C/f !!
Wavelength (metres) = Speed of light (metres per second)/ Frequency (cycles per second or Hertz)
😎

Yes they are my fleet.the Aziz,Yorkshireman,Cervia. Then I thought I'd have a change from tugs, now having nearly completed the scratch built 1/32 scale Brave borderer which can be seen on various posts on this site. Plus the new addition on the slipway to be revealed shortly.
Keep safe, regards Roger

cheers chaps for the info on ariel cable lengths. Dougie you are immense.

Hi Doug,

Thanks for the detailed explanation. I knew you would be able to give us all chapter and verse on the theory behind aerial lengths. 😆

Graham93

Hi Bill,
"I have had a similar problem in the past on another system and I used the old style GPO telephone wire,which is the same fine diameter."

Good choice👍
Main thing is a single solid core (like phone wire😉) not stranded like general use 'hook-up' wire.
I too have seemingly endless coils of multicore phone cable.
Used it for my 40MHz antenna on my Type 1A U Boat from bow to stern, just like the original.
Cheers, Doug 😎

I accept the challenge Graham😉

Jim,
"A question for the more technically minded the ariel cables on 35 mhz are often a couple of feet long and those on 2.4 may only be 6 to 8 inches long. If while you are replacing a lost cable on a 2.4 can you make it longer and will it give better reception. "

The short answer is NO as Graham says.
The 2.4Ghz RC band is a large chunk of the 2.4 -2.5GHz ISM band (Industrial Scientific & Medical band for license free transmitters - also used by Bluetooth, WLAN, WIFI, Smart Homes, Microwave cookers etc etc.
Actual frequency range usable for RC is 2.400 to 2.485 GHz.
The centre frequency of this band is thus 2.4425GHz, which has a wavelength of 12.274cm (or 4.832 inches). This is the correct 'effective' resonant length for our 2.4 Gig RXs, giving the best response over the whole band.
Why 'effective' length? You may have noticed that some RXs have a much shorter antenna wire outside the case, I have some with only about 5 or 6 cm visible. The rest is made up by a loading coil inside the case and the length of circuit track from the coil to the input stage of the RX amplifier.
BTW: 6 to 8 inches is unusually long for a 2.4 Gig, too long. 6" gives a resonant frequency of 1.967GHz and 8" a frequency of 1.499GHz, both outside our 2.4Gig RC band🤔

Lengthening the the wire outside the case puts the antenna off resonance causing a partial reflection of the input signal back to the antenna thus reducing the RX sensitivity to your TX signal.
Lengthening the wire moves the resonant tuning point to a lower frequency out of the 2.4 RC band☹️
All this applies to any single wire (monopole) antenna designed for use in a particular frequency range.
That's why all the 27, 35 and 40MHz RXs also had the warning not to change the antenna length.

Hope that this helps more than it confuses - and meets Graham's expectations😁
Cheers, Doug 😎

BTW2: you will find that some RXs have two antenna wires.
This is known as Antenna Diversity giving receiving two paths. If reception on one fades or is blocked by some object (another big model?) the RX will switch to the other always choosing the best signal available.
The two wires should be installed at right angles to each other. one VERTICAL and one HORIZONTAL.
This is to match the two antennas in the TX. One in the handle transmitting horizontally and the 'rubber duck' which should be adjusted or held so that it is vertical.
If you install both RX antennas in the same plane (either vertical or horizontal) you loose the advantage of this diversity.
Some more sophisticated (expensive🙄) sets even use separate channels for the two paths.

Thank you for your response. The reason I why I asked for clarafication was I have been for many years look ing for a model of my late father's. He built for a wealthy friend on a cost only basis, including the assembly of a Stuart Turner triple expansion engine. My dad was shocked to find it in junk shop a year later. His was larger I think and of bread and butter construction. Should anyone know of any likely contenders, do contact me here on the site.

Hi Jim,

The length of the aerial wire is important. The receiver is tuned to work with a defined length. If replacing it, you should use the same length. A longer, or shorter aerial will give worse reception.

As frequency increases, the aerial length reduces. That’s why 2.4GHz radios have shorter aerials than 35MHz. It is all to do with wavelength. I’m sure Doug could give a much more detailed explanation.

Graham93

Fine work nice looking boat.Are the others on the water your boats also.
Rick

Hi there
My Cervia was built from scratch by me, I purchased the plans in1973 and built the hull soon after,making a plug then a mould and then the final hull,my only regret was giving the moulds away at the time,I eventually finished it in1st lockdown, I have a pile of photos that I took of the real Cervia on a trip to Ramsgate harbour some years ago, these have helped with the finishing off greatly.
Here's a few more photos
Thanks for your interest Roger

the ariel cable to some of the small frsky receivers have a tendency to fall off and disappear. I keep a few old 35 mhz receivers and cut bits off the receiver cable for replacements seems to work for me.
A question for the more technically minded the ariel cables on 35 mhz are often a couple of feet long and those on 2.4 may only be 6 to 8 inches long. If while you are replacing a lost cable on a 2.4 can you make it longer and will it give better reception.

Hi,
Could you tell me please. Did you build your nice Cervia from scratch or refurb an old model?

Good evening Bill
Thanks for your prompt reply, I have a stash of different wires especially gpo wire, I never throw anything away, that has been left by different trades people visiting my factory, oh and yes I can this time remember where it is.
So thanks for the info, I will have a go at fixing the receiver now.
Thanks again, I will keep you posted to how successful I am
Regards Roger.

Hi Rogal.
Please see attached two pictures,one of which relates to your unit.
I have measured the length of both Aerials on mine and they are both 3cms from tip to the RX case.
Without disturbing mine the aerial seems to go immediately into the circuit board.
I have had a similar problem in the past on another system and I used the old style GPO telephone wire,which is the same fine diameter.
I have plenty of this style wire so if your happy to PM me your address I will pop a length in the post to you 👍.
Hope this helps.
Regards Bill.