Single conversion radio vs Dual conversion
08-27-2007, 03:30 AM
#1
Single conversion radio vs Dual conversion
I've tried to find an answer in the old posts, I'm sure this has been asked before. I have a JR transmitter (XP642) and recently purchased a GWS RD8SL 8channel receiver for it. It has a selector switch which changes from Negative to positive shift. It stated it was good for Futaba or JR radio systems. When I received it I found that the receiver and crystal were Dual Conversion. I have read on this site that all JR radio systems are Single conversions. Should I send these back or are they somehow compatible?
08-27-2007, 04:51 AM
#2
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RE: Single conversion radio vs Dual conversion
There is no problem working a dual conversion receiver with a JR (or any other) transmitter.
Dual conversion means that the receiver has two intermediate frequency (IF) stages instead of one. It should mean that the receiver is more selective in rejecting interference frrom a signal close to the frequeny it is being used.
The transmitter doesn't know or care whether the receiver is single or dual conversion. On a practical level I have JR transmitters and both single and dual conversion receivers (one is a JR, one a Hitec) and no problems at all.
Regards
Terry
Dual conversion means that the receiver has two intermediate frequency (IF) stages instead of one. It should mean that the receiver is more selective in rejecting interference frrom a signal close to the frequeny it is being used.
The transmitter doesn't know or care whether the receiver is single or dual conversion. On a practical level I have JR transmitters and both single and dual conversion receivers (one is a JR, one a Hitec) and no problems at all.
Regards
Terry
08-27-2007, 06:19 AM
#3
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RE: Single conversion radio vs Dual conversion
ORIGINAL: bgerth
I have read on this site that all JR radio systems are Single conversions.
I have read on this site that all JR radio systems are Single conversions.
"Conversion" is actually more of an advertising term.
There are a number of different techniques or designs to filter the signals a RX hears. One is called dual conversion and is described as routing the signal back through the conversion process a 2nd time. That brand then advertises their cheaper systems that don't do the rerouting as single conversion. It's their way of telling you which of their RXs are better and which are cheaper and why.
Receivers that use other filtering strategies aren't single conversion simply because they don't say they're double conversion. Notice the word is "conversion" not "filtered". Why do you think that is?
Advertising.
08-27-2007, 07:03 PM
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RE: Single conversion radio vs Dual conversion
I don't know of any JR transmitters that would have a problem with dual conversion receivers.
Most glow planes and larger electrics seem to have dual conversion receivers as standard equipment and smaller lighter planes have single conversion mainly because the single conversion receivers are smaller and lighter.
Dual conversion is less likely to glitch than single simply because it filters and proccesses the signal twice.
Most glow planes and larger electrics seem to have dual conversion receivers as standard equipment and smaller lighter planes have single conversion mainly because the single conversion receivers are smaller and lighter.
Dual conversion is less likely to glitch than single simply because it filters and proccesses the signal twice.
08-28-2007, 02:10 PM
#5
RE: Single conversion radio vs Dual conversion
Notice the word is "conversion" not "filtered". Why do you think that is?
Since lower frequencies are easier to work with the next stage listens for the difference. If its a single conversion reciever that "conversion" happens once. If its a dual conversion it happens twice to an even lower frequency to produce the final IF (intermediate frequency) that the reciever is tuned to listen to. This eliminates in band interference which can happen when certain channels in the 72mhz band are operated at the same time.
08-28-2007, 05:17 PM
#6
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RE: Single conversion radio vs Dual conversion
The IF stage(s) in a receiver do provide a filtering effect, because after conversion the signal is normally passed through a narrowband IF amplifier which helps to reject unwanted signals.
Terry
Terry
08-28-2007, 06:11 PM
#7
RE: Single conversion radio vs Dual conversion
I appreciate all of you posting on this and giving me an education. I really do want to know as much as I can about this. It's pretty amazing that all this comes together and works so well, (even up to a half mile away!).
This afternoon I plugged everything in and it worked great. I was afraid to take it out of its bubble packaging earlier until I was sure I had the correct stuff.
Thanks to all of you again, you've been a great help.
Bernie
This afternoon I plugged everything in and it worked great. I was afraid to take it out of its bubble packaging earlier until I was sure I had the correct stuff.
Thanks to all of you again, you've been a great help.
Bernie
09-01-2007, 04:44 PM
#8
RE: Single conversion radio vs Dual conversion
Net net is you don't have to know single from dual conversion. You do need to know postive shift from negative shift. Your JR, if it is 72 MHz and sold for the North American Market, is positive shift. So your receivers have to be positve shift or it won't talk to them.
The rest is nice to know but not necessary to know.
The rest is nice to know but not necessary to know.
09-06-2007, 05:39 AM
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RE: Single conversion radio vs Dual conversion
I'm glad someone has posted this!!!
I've got a large collection of radios and receivers, and the only one with any clear documentation is a Tower Hobby System3000 4-Channel. It came with a Dual Conversion receiver, so I just assumed that this made the radio a "Dual Conversion transmitter" and deduced that it had a Negative Shift since it is supposed to be compatible with Futaba.
In buying more receivers for many of my unfinished models, and picking up deals hither and yon, I've gotten Dual and Single conversion , positive and negative and auto detecting shifts, switchable shift, etc etc... I thought I'd try to buy a "single conversion" radio for the planes, and a decent 7 channel minimum for my helicopters...
So now, if I have this right: I can put the receivers in whatever model I wish, as long as the Shift is compatible. I can now probably use some of these Esky and Walkera radios for my planes (I have 6-7 of them) and eventually get a good comfortable computer radio that has Heli mixer programs AND Airplane programs.
I have a new Esky Honey Bee King II and a Walkera Model 52, (s well as many 4 channel helis) for my 6 channel or more radios. I'd like to use the Walkera (WK-071) radio for both, but the Walkera is PCM, and the Esky is listed as PPM, which I'm pretty sure is another way of saying FM. Since the Esky has seperates, could it be as easy as simply swapping a 6 channel PCM receiver for the FM ? As in plug in and forget?
Since all these radios have NO or Poor documentation, I pay hell trying to figure these things out. I just want a good flyable heli or three, that I can set up and fly outside, outside with some wind, and inside. I live in a normal house, so my understanding of "inside" is not a room that I can play full court bball in ..........
I've got a large collection of radios and receivers, and the only one with any clear documentation is a Tower Hobby System3000 4-Channel. It came with a Dual Conversion receiver, so I just assumed that this made the radio a "Dual Conversion transmitter" and deduced that it had a Negative Shift since it is supposed to be compatible with Futaba.
In buying more receivers for many of my unfinished models, and picking up deals hither and yon, I've gotten Dual and Single conversion , positive and negative and auto detecting shifts, switchable shift, etc etc... I thought I'd try to buy a "single conversion" radio for the planes, and a decent 7 channel minimum for my helicopters...
So now, if I have this right: I can put the receivers in whatever model I wish, as long as the Shift is compatible. I can now probably use some of these Esky and Walkera radios for my planes (I have 6-7 of them) and eventually get a good comfortable computer radio that has Heli mixer programs AND Airplane programs.
I have a new Esky Honey Bee King II and a Walkera Model 52, (s well as many 4 channel helis) for my 6 channel or more radios. I'd like to use the Walkera (WK-071) radio for both, but the Walkera is PCM, and the Esky is listed as PPM, which I'm pretty sure is another way of saying FM. Since the Esky has seperates, could it be as easy as simply swapping a 6 channel PCM receiver for the FM ? As in plug in and forget?
Since all these radios have NO or Poor documentation, I pay hell trying to figure these things out. I just want a good flyable heli or three, that I can set up and fly outside, outside with some wind, and inside. I live in a normal house, so my understanding of "inside" is not a room that I can play full court bball in ..........
09-06-2007, 07:16 AM
#10
RE: Single conversion radio vs Dual conversion
racoonster,
I don't know how you accumulated all these radios and receivers. My best recommendation would be to scrap all the odd transmitters and get on computer radio to fly all your planes.
Since you have pos and neg shift receivers and you want to fly Helis too, I would suggest either the Hitec Optic 6 or the Eclipse 7. both will fly all types and both have shift select so they can do pos and neg receivers.
This may be helpful.
What you need to know about receivers
http://www.rcuniverse.com/forum/m_44...tm.htm#4473239
Not that PCM, while it is FM, is brand specific. So a Walkera PCM receiver will not work with a Hitec PCM transmitter.
Or, scrap it all and go to 2.4 GHz.
I don't know how you accumulated all these radios and receivers. My best recommendation would be to scrap all the odd transmitters and get on computer radio to fly all your planes.
Since you have pos and neg shift receivers and you want to fly Helis too, I would suggest either the Hitec Optic 6 or the Eclipse 7. both will fly all types and both have shift select so they can do pos and neg receivers.
This may be helpful.
What you need to know about receivers
http://www.rcuniverse.com/forum/m_44...tm.htm#4473239
Not that PCM, while it is FM, is brand specific. So a Walkera PCM receiver will not work with a Hitec PCM transmitter.
Or, scrap it all and go to 2.4 GHz.
09-06-2007, 02:19 PM
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RE: Single conversion radio vs Dual conversion
ORIGINAL: racoonster
I'm glad someone has posted this!!!
I've got a large collection of radios and receivers, and the only one with any clear documentation is a Tower Hobby System3000 4-Channel. It came with a Dual Conversion receiver, so I just assumed that this made the radio a "Dual Conversion transmitter" and deduced that it had a Negative Shift since it is supposed to be compatible with Futaba.
In buying more receivers for many of my unfinished models, and picking up deals hither and yon, I've gotten Dual and Single conversion , positive and negative and auto detecting shifts, switchable shift, etc etc... I thought I'd try to buy a "single conversion" radio for the planes, and a decent 7 channel minimum for my helicopters...
So now, if I have this right: I can put the receivers in whatever model I wish, as long as the Shift is compatible. I can now probably use some of these Esky and Walkera radios for my planes (I have 6-7 of them) and eventually get a good comfortable computer radio that has Heli mixer programs AND Airplane programs.
I have a new Esky Honey Bee King II and a Walkera Model 52, (s well as many 4 channel helis) for my 6 channel or more radios. I'd like to use the Walkera (WK-071) radio for both, but the Walkera is PCM, and the Esky is listed as PPM, which I'm pretty sure is another way of saying FM. Since the Esky has seperates, could it be as easy as simply swapping a 6 channel PCM receiver for the FM ? As in plug in and forget?
Since all these radios have NO or Poor documentation, I pay hell trying to figure these things out. I just want a good flyable heli or three, that I can set up and fly outside, outside with some wind, and inside. I live in a normal house, so my understanding of "inside" is not a room that I can play full court bball in ..........
I'm glad someone has posted this!!!
I've got a large collection of radios and receivers, and the only one with any clear documentation is a Tower Hobby System3000 4-Channel. It came with a Dual Conversion receiver, so I just assumed that this made the radio a "Dual Conversion transmitter" and deduced that it had a Negative Shift since it is supposed to be compatible with Futaba.
In buying more receivers for many of my unfinished models, and picking up deals hither and yon, I've gotten Dual and Single conversion , positive and negative and auto detecting shifts, switchable shift, etc etc... I thought I'd try to buy a "single conversion" radio for the planes, and a decent 7 channel minimum for my helicopters...
So now, if I have this right: I can put the receivers in whatever model I wish, as long as the Shift is compatible. I can now probably use some of these Esky and Walkera radios for my planes (I have 6-7 of them) and eventually get a good comfortable computer radio that has Heli mixer programs AND Airplane programs.
I have a new Esky Honey Bee King II and a Walkera Model 52, (s well as many 4 channel helis) for my 6 channel or more radios. I'd like to use the Walkera (WK-071) radio for both, but the Walkera is PCM, and the Esky is listed as PPM, which I'm pretty sure is another way of saying FM. Since the Esky has seperates, could it be as easy as simply swapping a 6 channel PCM receiver for the FM ? As in plug in and forget?
Since all these radios have NO or Poor documentation, I pay hell trying to figure these things out. I just want a good flyable heli or three, that I can set up and fly outside, outside with some wind, and inside. I live in a normal house, so my understanding of "inside" is not a room that I can play full court bball in ..........
The cheap Walkera and Esky helis use 3in1 or 4in1 boards rather than proper recievers, so you may have difficulty with haveing all the channels correct for your radio.
04-03-2009, 03:27 AM
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RE: Single conversion radio vs Dual conversion
I have a Lanyu Cessna 747. The transmitter feels good and the reciever looks good. It seems to have enough range..The problem is.. I just bought another Lanyu reciever and can't find Chrystals. I have a reciever chrystal on Channel 3 in an old Hobby Zone Swift with a burned out speed control.. HOWEVER.. that Chrystal is 26.640 mhz and is NOT on the same frequency as my Lanyu RX which is 27.095. I use a chrystal of 27.095 Mhz in my Lanyu reciever to match the Lanyu transmitter on 27.095 and they appear to be exactly alike.. I also have a set of Lanyu chrystals on 27.195 which arrived marked TX on each one yet they appear to work in either the RX or TX.. Is it common for BOTH the TX and RX to use the same frequency chrystals and for them to be interchangeable? IF so why does the HZ reciever use a different Freqency Chrystal than it's transmitter. I don't think the HZ transmitter will work with my Lanyu reciever either. It don't think I can use the HZ Chrystal in my Lanyu reciever..? Could it be the HZ is a duel and the Lanyu is a single conversion system?..Frankly I like the Lanyu better than my EFLY-100B. How common is it to use RX and TX chrystals interchangable ? It appears to work on my Lanyu system..Thanks..
04-03-2009, 06:37 AM
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RE: Single conversion radio vs Dual conversion
Let say your receiver is set to receive 72.555 mz in order to do this the 72.555 need to be changed to your I.F. (intermediate frequency) let say that your IF is set to 10.7mz this is called your band pass freq. because it will not allow any freq. above or below 10.7mz. To pass. So to receive 72.555 your mixing freq. needs to be 61.855mz (72.555 - 61.855 = 10.7mz) if you change your mixing freq. up by 1 mz to 62.855 you will now be receiving 73.555. The mixing freq. can be changed by changing a crystal or by using a programmable VFO (variable frequency oscillator). ( programmable VFO is a synthesized receiver) in a duel receiver this happened twice with two IF’s 10,7mz and 455kc. This is why your rx. And tx. Crystals are different frequencies. There is no such thing as a duel conversion transmitter it transmits on the crystals freq.
04-03-2009, 07:58 AM
#14
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RE: Single conversion radio vs Dual conversion
Don't believe everything that you read.
The primary reason for dual conversion technology is image rejection.
04-03-2009, 08:08 AM
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RE: Single conversion radio vs Dual conversion
An image rejection mixer is often used to eliminate one sideband from converting to the IF frequency. The typical reason for this is noise figure: image noise from the unwanted sideband can easily pollute the noise figure of your receiver by 3 dB.
04-03-2009, 08:12 AM
#16
RE: Single conversion radio vs Dual conversion
I wonder how many readers understood the two post #'s 12 & 13 ?
The moderators that posted their replies hit the nail right on the head and kept it simple and understandable.
Hey, folks, this is a beginners forum. Not everyone has an EE. All the tech-know-how jumbo jumbo is great for the ego, but does little to help the original poster decide if he/she can use the receivers or not.
And the simple answer is maybe, but a better answer, as suggested by one of the moderators, is to go to 2.4 with multiple model memories and get everything on one transmitter.
The moderators that posted their replies hit the nail right on the head and kept it simple and understandable.
Hey, folks, this is a beginners forum. Not everyone has an EE. All the tech-know-how jumbo jumbo is great for the ego, but does little to help the original poster decide if he/she can use the receivers or not.
And the simple answer is maybe, but a better answer, as suggested by one of the moderators, is to go to 2.4 with multiple model memories and get everything on one transmitter.
04-03-2009, 08:37 AM
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RE: Single conversion radio vs Dual conversion
CGRetired
I was thinking maybe you are right but I reread my post and it is understandable I think I did a good job explaining the question without using all that technical lingo.
I was thinking maybe you are right but I reread my post and it is understandable I think I did a good job explaining the question without using all that technical lingo.
04-03-2009, 11:12 AM
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RE: Single conversion radio vs Dual conversion
Thanks...I looked on my Chrystals in both the Reciever and the Transmitter for my Lanyu system.. BOTH chrystals say...27.095 MHZ and both were marked RX.. Someone blacked out the RX on the transmitter one but they are idential. This is NOT what I know as normal and you just verified that for me... I can change the chrystals from the transmitter to the reciever and from the reciever to the transmitter and the radio works either way.. I understand what you said but this system seems to be different than what you described.. I have never seen one that interchanges chrystals from TX to RX before and frnakly, I am puzzled.. This Radio TX and RX is fairly new to the states and I find very little info on this system.. I love the way it feels in my hands and wish to change all my planes over.. I can buy more recievers for 10 bucks with NO chrystals.. I have not found anyone selling chrystals for this set.. I wonder if TWO TX chrystals from another 27mhz MF would work.. I have not tried that yet.. DOES anyone else have a LANYU 4 channel system or any knowledge of them..? Where can I find Lanyu chrystal sets for my new recievers ? Thanks, Chief.
04-03-2009, 02:29 PM
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RE: Single conversion radio vs Dual conversion
No, the Rx crystal is different than the Tx crystal.
There is a good thread somewhere here at RCU regarding the single and double convertion. It is nice to know as have been said.
I think that the thread is related with the Berg type receivers (which are great and small) with auomatic shift that means that will work with a Futaba (-) or JR (+) system.
There is a good thread somewhere here at RCU regarding the single and double convertion. It is nice to know as have been said.
I think that the thread is related with the Berg type receivers (which are great and small) with auomatic shift that means that will work with a Futaba (-) or JR (+) system.
04-03-2009, 03:59 PM
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RE: Single conversion radio vs Dual conversion
Well field TESTING has PROVED that YOU ARE CORRECT.. My chrystals BOTH have tags saying RX. The one in the Transmitter had been blacked out over the RX. I scraped it off to reveal RX and concluded they were exactly the same chrystals. Today I changed them about and the system DID NOT work..Lanyu must have ran out of TX markers and just used the RX tags on both the TX and RX chrystals.. I have two sets of Lanyu chrystals and BOTH are maked RX on both the transmitter and Reciever chrystals ..WRONG MARKINGS throwed me off.. I had NEVER before seen the TX and RX chrystals being interchangable.. SO NOW WE KNOW the TRUTH.. Don't trust the markings..Thanks for helping me with this.. Still I need another set of Chrystals for my new reciever that is on the way. Does anyone know if a set of 27 Mhz FM chrystals on 27.095 made for another brand of System will work in the Lanyu.... Lanyu chrystals seem to be hard to find without buying the entire plane.
04-03-2009, 04:21 PM
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RE: Single conversion radio vs Dual conversion
I have been a armature radio operator for over 40 years and I used this company to custom make crystals for me over 30 years ago they were very good, I just checked and they are still in business, If you can’t find the crystal give them a try they will make one for you good luck.
http://www.icmfg.com/
PS if your tx. freq. is 27.095 your rx. needs to be 26.64 for a typical IF
http://www.icmfg.com/
PS if your tx. freq. is 27.095 your rx. needs to be 26.64 for a typical IF
04-04-2009, 04:10 PM
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RE: Single conversion radio vs Dual conversion
ORIGINAL: wzak29
if your. freq. is 27.095 your rx. needs to be 26.64 for a typical IF
if your. freq. is 27.095 your rx. needs to be 26.64 for a typical IF
I should have asked what the RX chrystal freq. should be for 27.095 TX instead of all the other questons.. For this is what I really needed to know.
I have a 26.640 chrystal but did not know that it would work.. from now on I will assume I can just order a 26.640 for the other recievers and use my 27.095 TX on all of them..
Sometimes the answer is simple but how to ask thte question is not.. Aall I really needed to know now was how to can fly all of my planes on the same transmitter.. I will now look for a few 26.640 chrystals in FM..
OR.. is a chrystal a chrystal as long as the freq. is correct?
04-04-2009, 04:26 PM
#25
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RE: Single conversion radio vs Dual conversion
Is a crystal a crystal? Not necessarily, depends on the receiver design:i.e. what circuit? There are 3 basic designs and some use overtone crystals. The basic capacitance and inductance inherently present in the crystal cut ( X cut or Y cut) all have a bearing on what crystal will work: the frequency is only a part of the equation.
