I'm lost - Is the JR NER-236XZ a PCM-X receiver and thus not compatible with a Plain JR PCM-9 Tx? And, can someone explain to me the difference between the JR PCM 'X' Rx and the JR PCM 'S' Rx.

The lack of reference data from JR is a major negative in equipment selection.

Originally Posted by wjroper

I'm lost - Is the JR NER-236XZ a PCM-X receiver and thus not compatible with a Plain JR PCM-9 Tx? And, can someone explain to me the difference between the JR PCM 'X' Rx and the JR PCM 'S' Rx.
The lack of reference data from JR is a major negative in equipment selection.

JR/Graupner have had Two PCM systems on the market.
Original
Z-PCM (512) uses interlacing, e.g. every 21,77 ms channels 1 or 5, to 2 or 6, 3 or 7 and 4 or 8 gesendet, like 50 Hz half images on a TV screen that together give a 25 Hz full image. This would mean a frame rate of 2 complete frames for channel 1, or 43.5 ms. But if the data for channel 5 has not changed and the data for channel 1 is new, channel 1 will be sent in stead of channel 5, twice as fast or every 21,77 ms. Information about the channels that are actually transmitted in the received frame is of course also contained in the data. Accuracy is nine bits. A bit error means no data for 21.77 ms . Putting the "fast" channels in the 1 to 4 block and the slower ones in the 5-8 block allows optimal use of the command chain.
New (circa 2000)
S-PCM (1024) from JR/Graupner is a development of the previous system. To reduce downtime, smaller blocks of 10.65 ms are constructed. Four of these make up a complete 44 ms transmission message, providing data for each servo twice (21.30 ms frame). Accuracy is ten bits.

Extremely few JR receivers are Dual conversion.
JR have stuck with their patented unique signal processing system called ABC&W. ABC&W stands for Automatic Blocking Circuit with Window. ABC&W systems are said to have distinct advantages over single or dual conversion receivers. ABC&W systems create a very small electronic window that looks for the specific frequency that the receivers crystal is on. Any signal that is off spec for this window is rejected, and then the allowed signal is cleaned up, amplified, and re-routed through the window many, many times till all that is left is the pure signal on the channel that is coming from your transmitter and then sent on to the servos. This is said to take place without any noticeable delay of response from your stick movement to the servo. However, in recent years, a few USA club flying fields banned the use of the ABC&W RX due to unexplained "hits" and permit Dual conversion RX
only.

(FWIW - Futaba also has two PCM systems (512 & 1024) as does Hitec with PCM & the fastest of all which is QPCM)

Alan T.
Alan's Hobby, Model & RC FAQ Web Links

The 236XZ is a Z class receiver using ZPCM, you need to turn the modulation of the PCM9 to match it.

But thinking about it, the PCM 9 doesnt have the option to switch modulation settings. What other receivers have you tried ?

What a great resource you guys are! Thanks.

Follow up: I've got a JR PCM-9 which looks great, works perfectly and is on the Ham Radio Band. I was hoping to use these small light NER-236XZ receivers with that Tx. The other Rx's I have - which work perfectly - are too large.

So, my choices: Find a used JR TX on Ham band that uses PCM-X; alter the NER-236XZ Rx's to accept straight PCM; or put the PCM-9 in moth balls and start over.

You would need to be looking at a 642, 652, 662, X347, X388S, 8103 (or 8103ADT) to get Z class modulation. HH had their XP9303's imported with Z class disabled.

I've got a JR 652 transmitter and two NER 236 XZ recievers for sale if anyone is interested.

Thanks

I have (2) absolutely mint JR PCM9's....one is a Net-J129F airplane Tx w/2 J229P 9ch Rx's & the other is the rare Net-129HG Air/Heli Tx w/1 NER-910XZ 9ch Rx. They are beautiful units & one day I'm gonna try them out on a couple foamy high-wing trainers. Oh, BTW, my JR10X also has SPCM & ZPCM along with PPM for 2.4. Here's some pics....

Denny

Originally Posted by yorkiepap

I have (2) absolutely mint JR PCM9's....one is a Net-J129F airplane Tx w/2 J229P 9ch Rx's & the other is the rare Net-129HG Air/Heli Tx w/1 NER-910XZ 9ch Rx. They are beautiful units & one day I'm gonna try them out on a couple foamy high-wing trainers. Oh, BTW, my JR10X also has SPCM & ZPCM along with PPM for 2.4. Here's some pics....

Denny

I too have (2) PCM 9's Air version. They still work very well. I believe they are the early version (512 series). They are on Ham band which I flew for years on. But I want to convert to 72 mhz. So, I would need a module and receivers to match. What would I need as in model numbers, etc. to convert over.
I've been a JR person since Kraft went away. Thanks for any assistance in this area.
Mike

Hey Mike,
You can use any of the JR Net-J72P modules....Tx crystals are still available for most all the 72Mhz ch's.. The bugger is finding the J229P Rx's. The PCM9 owners manual doesn't specify any other Rx. You could post in the Radio Classified Section a "Wanted JR Net-J229P Rx" & you may find someone who would part with one or perhaps more. These radios are a joy to "feel"....solid like a bank vault. Here's a pic of one of my modules/Rx......

Denny

Originally Posted by yorkiepap

Hey Mike,
You can use any of the JR Net-J72P modules....Tx crystals are still available for most all the 72Mhz ch's.. The bugger is finding the J229P Rx's. The PCM9 owners manual doesn't specify any other Rx. You could post in the Radio Classified Section a "Wanted JR Net-J229P Rx" & you may find someone who would part with one or perhaps more. These radios are a joy to "feel"....solid like a bank vault. Here's a pic of one of my modules/Rx......

Denny

Fair enough ! Thanks Denny.

Mike