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HelicopterMain Discussion › jr 9xII 35mhz antenna length ?
01-21-2017 08:04 AM  10 months agoPost 1
skytrooper

rrNovice

South-Africa

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Please can anyone help.
i received a new replacement aerial for my jr 9x2II 35mhz radio but unfortunately it doesn't fit, and compared to my broken aerial the sections are somewhat shorter, does anyone know what the exact length is tip to tip so i can shoe horn an aerial from the broken one's i have to make one with the correct length.

a friend of mine has got a jrR 388s and tells me the lenght is 1150mm from the base to the top, can anyone confirm if this is the correct length for the jr radio frop tip to top incl button and if it is the same length for the 9xII jr radio i have ?

Throttling up for the first time, i can't wait....

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01-21-2017 10:27 AM  10 months agoPost 2
skytrooper

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South-Africa

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not even a drop of 9xII 35mhz transmitters left in the universe ?

Throttling up for the first time, i can't wait....

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01-21-2017 02:46 PM  10 months agoPost 3
skytrooper

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South-Africa

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i had 2 people telling me the lengths, one said it's 1150mm and the other said 1117mm, anyone know why it differs, does every 35mhz radio has it's own sized aerial or are they changed in size according to which country one lives in, i don't want to blow the radio or decrease it's range so i still don't know what length it should be.

Throttling up for the first time, i can't wait....

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01-21-2017 08:22 PM  10 months agoPost 4
utahbob

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St. George Utah

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like to help..

I been rc'n since '94..never heard of that radio or 35mghz..if that radio is that old maybe Jr would take it back for museam purposes and give you a great price on a new one! Maybe a picture could help.

I do a great decending funnel!

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01-21-2017 09:39 PM  10 months agoPost 5
Heli_Splatter

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USA

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Used outside USA... in US 27mhz, 72mhz, and Ham Freq 50mhz were/are used. There may be others. That is why no-one is responding. It will have to be someone OCONUS.

It may be possible to modify another longer antenna to match his needs. Or he may find someone to dig it out of their collection.

I don't agree with his assessment of 2.4Ghz, but he is entitled.

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01-22-2017 12:07 AM  10 months agoPost 6
flycatch

rrApprentice

Barstow, California

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35mhz Antenna length

I went on-line and goggled 35mhz rc receivers. Came up with several hits and the specifications for each receiver showed antenna length as 800mm.

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01-22-2017 12:11 AM  10 months agoPost 7
Heli_Splatter

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USA

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Transmitter not receiver.

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01-22-2017 09:50 AM  10 months agoPost 8
skytrooper

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South-Africa

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Thanks i had a few people measuring theirs and the answers i received was form anything between 1158-1170mm so i'm sorted thanks,the only reason i do not go 2.4 is because i have seen people lose their dear planes on more than one occasion where i fly, everything these days work on 2.4 so we picked up 10 2.4 signals in our area, so staying at 35 will keep me safe, spcm of course never only had 3 glitches non-crashes recovered in air, in 6 years.

Throttling up for the first time, i can't wait....

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01-22-2017 06:19 PM  10 months agoPost 9
Four Stroker

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Atlanta

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I flew for 40 years on 72 MHz. Only switched when I was shot down by a fellow club member. I had the card. Only glitches on 2.4 GHz were from a Futaba PS10 regulator. On the other hand, there is that unmentioned brand of 2.4 radio that I have watched fall out of the sky for 10 years. If you avoid that brand, 2.4 is completely reliable.

Your TX antenna can be base loaded. Probably the same antenna for 35, 40, 72 MHz as a cost savings. The hand held TX/Antenna is grossly inefficient anyway and a little won't matter. 1/8 wave for 35 is 1071 mm. Old Multiplex TX used a center loaded antenna.

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01-22-2017 07:28 PM  10 months agoPost 10
MDSCUSTOMS

rrApprentice

North Wales, U.K.

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35 Mhz was commonly used in the UK, I still fly on it using a Hitec Eclipse 7 set with no problems as so few people are using it now.

There is an aerial on ebay which may fit yours, not sure what the length is but it fits various JR Tx's. The screw thread will be standard size across all of them.

http://www.ebay.co.uk/itm/JR-35MHz-...nQAAOSwbsBXkNoN

Mark

I'm only here coz I'm not all there !!

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01-22-2017 09:23 PM  10 months agoPost 11
Heli_Splatter

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USA

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Pretty daming claims made.

I am interested, what is the brand? I have only flown 2.4 and I can assure you that I have never had a plane fall out of the sky.
On the other hand, there is that unmentioned brand of 2.4 radio that I have watched fall out of the sky for 10 years. If you avoid that brand, 2.4 is completely reliable.

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01-23-2017 12:43 AM  10 months agoPost 12
MDSCUSTOMS

rrApprentice

North Wales, U.K.

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Not as damning as you think,

Given the rise of Wifi and mobile phones etc, there are people using boosters to improve their signal on same. Highly recommended you don't fly in any of those hotspots or near a mast which has 2.4 Ghz relay antennae fitted, they will wipe out the signal from your Tx no problem due to the much stronger power output. This has been a known issue for a while.

Meanwhile, I am still happily flying around on 35 Mhz, that long aerial is a pain sometimes but I can live with that just as I did back in the 27 Mhz days. I still have a few 27 Mhz sets too.

Mark

I'm only here coz I'm not all there !!

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01-23-2017 01:18 AM  10 months agoPost 13
AirWolfRC

rrProfessor

42½ N, 83½ W

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Your antenna length is 300 / frequency MHz / 4 for a quarter wave whip measured in meters.

Subtract about 3% or 4% if you want to get picky. That varies depending on antenna diameter and if you have a button on the tip (capacity hat) to keep from poking someone. 299,792 KM/sec is the speed of light in free space but I just use 300.

If you have a loading coil in the antenna, it will be much shorter depending on the coil.

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01-23-2017 10:34 PM  10 months agoPost 14
Infarcted

rrApprentice

downunder

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I still have a JR 9X II and can confirm it is 1150 mm (yes I measured it !)

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