joseph77

Hi there,

Can someone explain to me what is meant by "Dual conversion" when it is talked about with receivers.

Thanks,

Joseph.

barelias

I Do have that on my futaba reciver !!! and i have been wanting to know that!!!glad u asked, hope some one helps both of us.
im thinking it should be some thing good

Redback

Receivers convert the radio frequeny received to a lower frequency (called the intermediate frequency or IF) before decoding the signal. I think the usual IF is 455kHz or thereabouts.

Dual conversion receivers carry out this frequency conversion twice, so there are two IF stages.

Reason for doing this is to increase the selectivity of the RX, ie to make it more immune to interference.

Some time since I did my radio theory, however I believe the above is correct

If not no doubt someone will jump in.

Terry

Matt Kirsch

My Feedback: (21)

That's pretty much it in a nutshell. I've got little to no radio theory in my head at all, so you've got the advantage of having a more technical explanation

Don't get the wrong idea that single conversion is a "bad thing." It's not, in and of itself. A properly designed single-conversion receiver, like the Berg brand, and most of JR's, are just as sensitive and just as resistant to noise/interference as any dual-conversion receiver on the market. Low-end park flyer receivers like the Hitec Feather and GWS Pico/Naro are more prone to glitching because they were made to be inexpensive, not because they're single-conversion.

joseph77

Thanks,

The reason im asking is i recently purchase a GWS R-6N receiver and cystals from my LHS. Im trying to connect it up using

Sanwa VG 600 Tx
GWS R-6N Rx (using 35mhz ch 64)
Jeti JES 30 ESC (using 8.4v 1050mAh and speed 480 motor)
2x sanwa SX-091 servos

It not having it though. Can someone please confirm what servos/ESC connects where on the Rx, i think ive done it right but we can take it from there.

Thanks.

joseph77

Me again,

After having a little play i just think that the GWS RX is not compatable with the Sanwa VG 600. Can any one confirm this for me?

Thanks.

jakjr

My Feedback: (18)

receivers come in two shifts, negative and positive. Negative shift works with hitec and futaba radios, positive shift works with JR, airtronics, and I "think" sanwa radios. You probobly either somehow got the wrong channel crystal by mistake or bought the wrong shift receiver.

The servos/ESC should be plugged into the receiver in this order, slot 1- ailerons, slot 2 - elevator, slot 3 - ESC, and slot 4 - rudder. Also check that you have the servos/ESC plugged in the right way, you may just have the connectors plugged in upside down.

Im not shrue if you can turn the BEC on/off on your ESC but check it and make sure its set to on, Otherwise nothing will work as teh receiver wont be getting any power.

joseph77

Jakjr,

thanks for the input. Have you given me the servo layout for 4ch Rx not the 6ch Rx? if im reading the instructions right should it be 1-ESC,2-Aileron,3-Elevator,4-Rudder for the 6ch Rx im using? The Crystals are a definate pair. BEC is turned on (the ESC defo works - its out of another model) This leaves this Pos/neg shift thing (which i was worried about!!) The instructions say -

"For 72MHZ, you must select Futaba/Hi-tec for negative shift ("F" sticker on the receiver) or JR/Airtronincs for positive shift ("J" sticker on the receiver), other wise it will not operate."

1, What is meant by positive/negative shift?
2, For 72MHZ? i thought i was 35MHZ?
3, I cant see any stickers on the Rx (maybe its got an "F" on, see the attached picture next to the 2 "C"s (one in the other under the CE)
4, Will the GWS Tx work this if my sanwa/airtronics wont? (i can pick one up for under £30)

When i turn on my TX and RX it seems that its receiving a signal but everything is out of control.

Your right this must be a proper hobby now cause its starting to cost me loads and i dont know how much longer i can lie to my girlfriend (everything i seem to buy is on "offer")

Joseph.

jakjr

My Feedback: (18)

AH, I see the problem, you live in the UK and I live in the US therefore my information was incorrect for you.

First of all, Your radio is 35mghz (Uk standard for aircraft is 35, US is 72), the GWS receiver you have wont work with your radio as it is made for 72mghz radios. You will need a receiver that is made for 35mghz operation.

The servo placement for a 4 channel and the first 4 slots on a 6 channel receiver is the same, the 5th and 6th channels are for retracts and flaps. BUT, if your radio is a mode 1 (throttle is on the right stick) the servo placement will be different from what I said earlier as here in the US most everyone (including me) uses mode 2 radios (throttle on left stick) and thats what the placement setup I posted is for.

The F next to the 2 c's on your receiver stands for FCC (federal comunications commision) they regulate the radio waves and whatnot in the US (maybe in other parts of the world as well, I dont know for shure)

Yes, a GWS TX will work fine with your recevier (as long as the shift is the same, mghz is the same, and channel is the same), but I dont know about using 72mghz equipment in the UK, it migth not work right over their as like Is aid before the Uk standard for rc aircraft is 35mghz and US is 72mghz.

Im not shure what Negative shift and postive shift actualy mean (other than - is hitec/futaba and + is JR, airtronics and sanwa), but for your Tx and Rx to operate together they must be on the same shift.

Right now I'm gonna say teh best thing to do is try to return the receiver and eitehr get your money back or get one that works with your equipment. Just tell them you didnt know the receiver wouldnt work with your stuff nad ask if they can either give you your money back or switch it for one that will work.

joseph77

thanks again,

the receiver is 35MHZ (little sticker on the back) i think its just the pos/neg shift thing, so ill probably order the GWS transmitter for this receiver and when i get my next Rx ill make sure its compatable with the sanwa vg 600. Mean while if theres anyone who can explain this pos/neg shift i'll be much appreciated.

This hobby cost money, even if you go with a 35 quid model, youll need to spend at least another 100 to get it flying [:@]

joseph.

joseph77

Hi there problem solved -

A duff crystal from the LHS

i was not amused

Also the pos/neg shift is just simply which way the servos move (easy to cure using the servo reverse on the Tx) for any one who wanted to know.


Joseph.