Notices
RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

JR Receiver Advice Needed

Old 09-10-2002, 05:35 AM
  #1  
KeithB
Senior Member
Thread Starter
My Feedback: (1)
 
KeithB's Avatar
 
Join Date: Jan 2002
Location: Garland, TX
Posts: 630
Likes: 0
Received 0 Likes on 0 Posts
Default JR Receiver Advice Needed

I fly JR and I'd like to go PCM in my new plane. I'm unwilling to fly a single conversion receiver which leaves me with one choice for PCM, the JR R945S. This is JR's only PCM Dual Conversion receiver (as far as I know).

Though dual conversion has been around for eons I'm just a little concerned because this appears to be JR's first time to produce a dual conversion receiver. Given the way version 1.0 products are I'd like to hear from others that are flying this receiver and see if there are any known problems with it.

I know that JR is top notch, which is why I fly them, I'm just being careful :-)

Thanks,
Keith
Old 09-10-2002, 08:41 AM
  #2  
Dansy
My Feedback: (53)
 
Dansy's Avatar
 
Join Date: Mar 2002
Location: Prescott, Ont.
Posts: 2,985
Received 159 Likes on 142 Posts
Default JR Receiver Advice Needed

No it's not the first time they produce dual conversion.....I have a two 940S which is the version just prior the 945S, an while I cannot recall the number they had it before that....!

I also own one 950 and two 955 and frankly I cannot tell the difference these and the 940, while flying my pattern airplanes

Daniel D.
Old 09-10-2002, 02:17 PM
  #3  
thomasb
Senior Member
 
Join Date: Jun 2002
Location: Private, CA
Posts: 344
Likes: 0
Received 0 Likes on 0 Posts
Default SC vs. DC

I'm unwilling to fly a single conversion receiver which leaves me with one choice for PCM, the JR R945S.
Poor Rx designs, especially the cheap park fly type, have given the SC Rx a bad rap.

JR's SC models are very selective and are great performers. Do not confuse them with lower quality designs. Their ABC&W circuitry is very effective and the Rx's front end is well designed.

This white paper is good reading: http://www.bergent.net/SC-DC.pdf
Old 09-10-2002, 09:29 PM
  #4  
KeithB
Senior Member
Thread Starter
My Feedback: (1)
 
KeithB's Avatar
 
Join Date: Jan 2002
Location: Garland, TX
Posts: 630
Likes: 0
Received 0 Likes on 0 Posts
Default JR Receiver Advice Needed

Daniel,

You're absolutely correct that JR had dual conversion receivers before the 945S, I realized that about 10 minutes after I made that post. I knew I'd catch grief from my statement but I still wanted to get opinions on the 945s

As to the ABC&W circuitry it probably works great in some areas, otherwise I'm sure JR couldn't keep selling single conversion receivers. But for some reason in my area the dual conversion does much better. I have a PCM JRPR649 that is single conversion with the ABC&W (costs $160). I also have a 7 channel PPM Hitec Dual Conversion receiver (costs $60). For what ever reason I get many more hits on the JR than the Hitec.

This probably has something to do with the particular interference where I'm flying. However, given that this is the case I'm just not willing to put a single conversion receiver in my new 2M pattern plane.

Thanks for your help,
Keith
Old 09-11-2002, 04:17 AM
  #5  
BPKlein
Senior Member
My Feedback: (1)
 
Join Date: Jun 2002
Location: Lake Dallas TX
Posts: 173
Likes: 0
Received 0 Likes on 0 Posts
Default JR Receiver Advice Needed

Keith,

Where do you fly? I fly at Metro East off of I-80. I also use JR stuff, but have had the opposite experience as you. I have been using JR 649's (sc) and JR 940's (dc). I get more hits with the 940's in my gas powered planes than with the 649's.

Bryan K.
Old 09-11-2002, 06:46 AM
  #6  
KeithB
Senior Member
Thread Starter
My Feedback: (1)
 
KeithB's Avatar
 
Join Date: Jan 2002
Location: Garland, TX
Posts: 630
Likes: 0
Received 0 Likes on 0 Posts
Default JR Receiver Advice Needed

I fly at Richardson Radio Control Club (RRCC) and occasionally off of Renner Road (a rouge field).

I've gotten hits on the JR 649 at both fields, but much more frequently at the Renner location. With my Hitec (3800 I think) I get very few hits in either location, though still an occasional one at Renner.

I'd really like to run PCM but don't want to go to the 945 if it will still get more hits than my Hitec. The Hitec isn't PCM, but at least it doesn't get many hits (it's a lot cheaper too!).

Keith
Old 09-11-2002, 02:27 PM
  #7  
thomasb
Senior Member
 
Join Date: Jun 2002
Location: Private, CA
Posts: 344
Likes: 0
Received 0 Likes on 0 Posts
Default JR Receiver Advice Needed

If your radio "hits" are due to EMI/RFI interference originating on the model (metal-to-metal noise, gasser ignition noise, local R/C equip noise, etc.) then this is not a SC vs. DC receiver issue.

DC Rx's offer good immunity to intermodulation troubles, but these are entirely different animals. However, JR's Rx's have circuitry to minimize these issues. IM is discussed here: http://www.uoguelph.ca/~antoon/hobby/rip.htm

If your interference is nearly constant, rather than intermittent, then it may be IM, 2IM, or 3IM. If severe, these troubles will affect DC Rx's and JR's ABC&W equipped SC Rx's. There are solutions to minimizing these affects, including such things as observing proper pilot spacing and avoiding certain R/C channels when local TV chnl 4 is in use.

By chance have you identified the interference? That is the best place to start. Then a recovery plan can be devised. Of course going to PCM will mask EMI/RFI interference problems, but that is a whole 'nother subject in itself.

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 -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.