Jr R700 Rx
04-28-2002, 11:18 PM
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04-29-2002, 04:15 PM
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JR700
OZ,
Just saw one in person today......WoW!
Its a little dude.
Close to the same price as the 6..
I cannot figure out why JR does not just put this rx in all.
I will have one....
Doc
Just saw one in person today......WoW!
Its a little dude.
Close to the same price as the 6..
I cannot figure out why JR does not just put this rx in all.
I will have one....
Doc
04-29-2002, 04:34 PM
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JR R700 RX
Doc,
I have two of them, one in my Astrohog and one in a 1/4 scale Cub.
I have expereinced glitching with them, particuarly when you have another flyer on adjacent channel.
In Australia our channels are 10khz apart, not sure about what you have over there. However the way the frequency peg boards are designed you can not put a key in the bord on say 622 and 633. Instead you could only insert in say 620, 622, 644 etc or 621 , 623 etc . This maintains 20khz seperation. BTW I am talking frequency of 622 = 36.22 Mhz.
I have wandered on a bit of a tangent here however will try and do a Billy Connolly and come back on track!
When flying recently at an invite meet my Hog was gettering all over the place, upon investigation there was a flyer on ch 620.
As the R700 is a single conversion RX I have been told that it is quite suscepotible to adjancet ch interferrence.
JR use a filtering system called ABC&W. Now what that is exactly I do not know, suspect maybe an active filter or a narrow knotch type ceramic filter maybe.
Still I do not think it is as good as dual conversion.
As I have now found out to get dual conversion in a JR you have to buy the top of the range 10 ch PCM RX. Here in OZ that is about $350 AUD do the exchange rate math $AUD = 0.53 USD
Damn expensive RX! Hitec 7 and 8 ch PPM RX however are dual conversion and I never get a hit on them. I have 3 and they work great.
Maybe Ladyhawk has some words of wisdom?
as said I am not sure how your freq boards work over there so maybe it is not an issue.
But yes they are a tiny little unit!
cheers
Peter
I have two of them, one in my Astrohog and one in a 1/4 scale Cub.
I have expereinced glitching with them, particuarly when you have another flyer on adjacent channel.
In Australia our channels are 10khz apart, not sure about what you have over there. However the way the frequency peg boards are designed you can not put a key in the bord on say 622 and 633. Instead you could only insert in say 620, 622, 644 etc or 621 , 623 etc . This maintains 20khz seperation. BTW I am talking frequency of 622 = 36.22 Mhz.
I have wandered on a bit of a tangent here however will try and do a Billy Connolly and come back on track!
When flying recently at an invite meet my Hog was gettering all over the place, upon investigation there was a flyer on ch 620.
As the R700 is a single conversion RX I have been told that it is quite suscepotible to adjancet ch interferrence.
JR use a filtering system called ABC&W. Now what that is exactly I do not know, suspect maybe an active filter or a narrow knotch type ceramic filter maybe.
Still I do not think it is as good as dual conversion.
As I have now found out to get dual conversion in a JR you have to buy the top of the range 10 ch PCM RX. Here in OZ that is about $350 AUD do the exchange rate math $AUD = 0.53 USD
Damn expensive RX! Hitec 7 and 8 ch PPM RX however are dual conversion and I never get a hit on them. I have 3 and they work great.
Maybe Ladyhawk has some words of wisdom?
as said I am not sure how your freq boards work over there so maybe it is not an issue.
But yes they are a tiny little unit!
cheers
Peter
05-06-2002, 11:00 AM
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Frequencies
PETER,
Our freq's are
Example
Channel 39 is 72.570 MHZ
Channel 38 is 72.550 MHZ
If my electrical memory and calculations are correct...This would be a 20K separation.
To obtain what channel by frequency
I add 21 to the number after the decimal, and divide by 2
72.570
+ 21
-----------
72.78
78 divided by 2 = 39 Channel 39
Hope I didn't bore you
Doc
Our freq's are
Example
Channel 39 is 72.570 MHZ
Channel 38 is 72.550 MHZ
If my electrical memory and calculations are correct...This would be a 20K separation.
To obtain what channel by frequency
I add 21 to the number after the decimal, and divide by 2
72.570
+ 21
-----------
72.78
78 divided by 2 = 39 Channel 39
Hope I didn't bore you
Doc
05-09-2002, 02:20 PM
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JR R700 RX
you are right LH.
For mine I'd rather have dual conversion then a uP of dubious value and effectiveness.
I have witnessed first hand how badly these rx suffer from adjacent ch interfference.
HITEC have dual conv on their 7 and 8 ch PPM rx and they perform great!
cheers
Peter
For mine I'd rather have dual conversion then a uP of dubious value and effectiveness.
I have witnessed first hand how badly these rx suffer from adjacent ch interfference.
HITEC have dual conv on their 7 and 8 ch PPM rx and they perform great!
cheers
Peter
05-18-2002, 01:33 PM
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Jr R700 Rx
Peter,
The R700 is the latest PPM Rx from JR and next one is close behind which will be the R800 SPCM Rx. These have been assembled in Malaysia, hence the competitive price.
The front end circuitry ( the important bit ) uses Patented circuitry called ABC&W ( Automatic Blocking Circuit and Window ).
In laymans terms this is signal conditioning and means Attenuation, Filtering and Feedback. Another principle, Dual Conversion, conditions the signal in two stages, hence Dual.
JR has gained a world wide reputation for reliability over many years using ABC&W within their single conversion Rx's. JR Rx's are now using a second generation ABC&W.
JR produced a DC Rx by public demand - not that they found DC to be superior over ABC&W. In a conventional ( not JR ) DC Rx you can have up to three crystals, a ceramic filter and a ceramic resonator, all of which are susceptable to damage by severe vibration and hard landings. Within a JR SC Rx just one crystal and one ceramic filter.
Our model Rx's are placed in the unusual environment of rapidly changing distance with respect to Tx source; I can think of no other situation where the change is as fast.
Don't be worried about the terms 2nd and 3rd order. 3rd order intermodulation is so low in power that manufacturers don't measure it.
I would be interested to know which Tx you are using with the R700? I've checked four R700's and all of them needed the Demodulator Coil retuning. Seemingly Malaysian alignment is different to Japanese alignment of Rx's. This also reduces random clocking of servos when Tx is OFF - a problem identified by other users.
No pistols or swords at thirty paces thank you !! Just voicing my experience.
The R700 is the latest PPM Rx from JR and next one is close behind which will be the R800 SPCM Rx. These have been assembled in Malaysia, hence the competitive price.
The front end circuitry ( the important bit ) uses Patented circuitry called ABC&W ( Automatic Blocking Circuit and Window ).
In laymans terms this is signal conditioning and means Attenuation, Filtering and Feedback. Another principle, Dual Conversion, conditions the signal in two stages, hence Dual.
JR has gained a world wide reputation for reliability over many years using ABC&W within their single conversion Rx's. JR Rx's are now using a second generation ABC&W.
JR produced a DC Rx by public demand - not that they found DC to be superior over ABC&W. In a conventional ( not JR ) DC Rx you can have up to three crystals, a ceramic filter and a ceramic resonator, all of which are susceptable to damage by severe vibration and hard landings. Within a JR SC Rx just one crystal and one ceramic filter.
Our model Rx's are placed in the unusual environment of rapidly changing distance with respect to Tx source; I can think of no other situation where the change is as fast.
Don't be worried about the terms 2nd and 3rd order. 3rd order intermodulation is so low in power that manufacturers don't measure it.
I would be interested to know which Tx you are using with the R700? I've checked four R700's and all of them needed the Demodulator Coil retuning. Seemingly Malaysian alignment is different to Japanese alignment of Rx's. This also reduces random clocking of servos when Tx is OFF - a problem identified by other users.
No pistols or swords at thirty paces thank you !! Just voicing my experience.
