JR Radio & Spektrum Radios Discuss all your JR and Spektrum gear.

Single Conversion vs Dual Conversion

Reply

Old 12-31-2002, 08:35 PM
  #1  
tiggerinmk
Senior Member
Thread Starter
 
Join Date: Dec 2002
Location: Milton Keynes, UNITED KINGDOM
Posts: 1,527
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

This is not an immediate requirement, more a query out of curiousity........

I have noticed that a lot of FM receivers by other manufacturers are dual conversion whereas almost all (except the 945 I believe) JR receivers are single conversion.

One person on a recent related thread here even went as far as to say that dual conversion is necessary on FM to eliminate interference. This is obviously not the case, at least with JR receivers.

So, what is the difference between single and dual conversion, and why is it that all JR receivers except the 945 are single conversion?

What prompted this question is that I mistakenly bought some d/c cryatals a while ago and probably won't have a use for them...
tiggerinmk is offline  
Reply With Quote
Old 12-31-2002, 08:57 PM
  #2  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

The reason JR can use single conversion systems and still have excellent performance is ABC&W technology that is used in JR receivers. ABC&W acts like automatic gain control on the antenna circuit which filters out unwanted noise and only accepts input on the frequency it is supposed to accept.
dsnyder is offline  
Reply With Quote
Old 12-31-2002, 09:09 PM
  #3  
tiggerinmk
Senior Member
Thread Starter
 
Join Date: Dec 2002
Location: Milton Keynes, UNITED KINGDOM
Posts: 1,527
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Thanks for the prompt answer!

However, that leaves one question...

According to the HH site there are two top end 10 channel receivers, the 945 & 955.

The only difference I can see between them is that one is single and the other is dual conversion. They both appeared to be released on the same date (Oct 19 2001) and both replace earlier models.

So at least at the top end of the hobby there must be a difference?
tiggerinmk is offline  
Reply With Quote
Old 01-02-2003, 01:54 PM
  #4  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Yes, that is correct, the 955 is single conversion and the 945 is dual conversion. In some applications, one will perform slightly better than the other, but there really isn't a way to tell before trying it. It depends on the application, the area it is to be used in, and a few other factors, and depending on those factors, one may work better than the other.
dsnyder is offline  
Reply With Quote
Old 01-02-2003, 03:03 PM
  #5  
tiggerinmk
Senior Member
Thread Starter
 
Join Date: Dec 2002
Location: Milton Keynes, UNITED KINGDOM
Posts: 1,527
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Thanks for the info!

I'm sure that's cleared a few things up for many JR receiver users....
tiggerinmk is offline  
Reply With Quote
Old 01-02-2003, 03:11 PM
  #6  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

No problem!
dsnyder is offline  
Reply With Quote
Old 01-02-2003, 03:51 PM
  #7  
ml3456
 
Join Date: Oct 2002
Location: Darien, IL
Posts: 626
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Danny,

Does the 659 PCM receiver use single conversion crystals?

ML
ml3456 is offline  
Reply With Quote
Old 01-02-2003, 03:55 PM
  #8  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Yes, the 649 as well as all other current JR receivers besides the 940 and 945 use single conversion crystals. They are gray cased crystals, the dual conversion crystals for the 940 and 945 are red cased.
dsnyder is offline  
Reply With Quote
Old 01-02-2003, 07:53 PM
  #9  
DavidO
Senior Member
 
Join Date: Aug 2002
Location: Lancs, UNITED KINGDOM
Posts: 108
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Danny,
Do the 945 and 955 Rx's use ABC&W ?
It's not stated on the cover labels.
DavidO is offline  
Reply With Quote
Old 01-02-2003, 07:55 PM
  #10  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Yes, they are ABC&W receivers.
dsnyder is offline  
Reply With Quote
Old 01-02-2003, 08:03 PM
  #11  
DavidO
Senior Member
 
Join Date: Aug 2002
Location: Lancs, UNITED KINGDOM
Posts: 108
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Wow !!!
That was a lightning reply.....1min 30sec's.
Many thanks.
DavidO is offline  
Reply With Quote
Old 01-02-2003, 08:04 PM
  #12  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

No problem!
dsnyder is offline  
Reply With Quote
Old 05-06-2003, 04:34 PM
  #13  
woodscra
Senior Member
My Feedback: (23)
 
Join Date: Dec 2001
Location: frisco, TX
Posts: 895
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default single conv.

Originally posted by dsnyder
Yes, that is correct, the 955 is single conversion and the 945 is dual conversion. In some applications, one will perform slightly better than the other, but there really isn't a way to tell before trying it. It depends on the application, the area it is to be used in, and a few other factors, and depending on those factors, one may work better than the other.
What are "some applications" where single conversion should not be used? There must be some criteria in which JR would recommend against it, the more the consumer knows the better decision he can make.

Thanks
woodscra is offline  
Reply With Quote
Old 05-06-2003, 04:44 PM
  #14  
dsnyder
 
dsnyder's Avatar
 
Join Date: Jun 2002
Location: Champaign, IL
Posts: 9,365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

Unfortunately there is no hard fast rule on that, or any criteria that I can tell you where one will be better than the other. It is dependent on the area it is being used in, the type of model, the engine, equipment, etc. And it would not be that single conversion should not be used, but rather that dual conversion may work slightly better, or vice versa.
dsnyder is offline  
Reply With Quote
Old 05-11-2003, 05:46 PM
  #15  
bjw4072
Senior Member
My Feedback: (6)
 
Join Date: Apr 2002
Location: Fairbanks, AK,
Posts: 140
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

It seems to me that a dual-conversion receiver with ABC&W will always be better (or at least no worse) than a single conversion receiver with ABC&W in terms of interference rejection etc.

However, a single conversion receiver has a lower parts count and is simpler. Therefore if a double conversion receiver is not necessary for most flyers for reasons of interference issues, then it seems to make sense to use a lower cost single-conversion receiver that is in principle more reliable in terms of potential electronic parts failures because of its low parts count.

(just my thoughts, maybe there is something else to this question)

Brent
bjw4072 is offline  
Reply With Quote
Old 05-12-2003, 12:54 AM
  #16  
woodscra
Senior Member
My Feedback: (23)
 
Join Date: Dec 2001
Location: frisco, TX
Posts: 895
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Single Conversion vs Dual Conversion

There is not much of a price difference between the 955 and 945 RXs. About $10. Is $10 buying something really helpful or not?
woodscra is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service