Paul Newell 2

Andy, Not guilty! But do know of the book to which you refer. Phil, Thanks for the thanks. It is only in later years that the significance of the books became apparent.

Hi Pete, Have to say that, like you, I was inspired into electronics by others from the modelling fraternity. In my case it was Idris Frances of Flight Link. At a later stage my RC involvement introduced me into a business partnership with Peter Cabrol of C&L who earlier had produced the Climax R/C equipment. Apart from mundane industrial applications I designed equipment for fully automated leisure industry ride systems, laser lighting controls for ‘the Who’ and we even used variations of the R/C systems for ‘Spitting Image’ and Ford tractors. Copies of my books and other Radio Modeller publications are on my bookshelf. Examples of most of the Microtrol equipment are still in the loft, except for that first Tx with the awful large air spaced coils in the output circuit. - I robbed the Tx for the stick assemblies. Top specification equipment these days is beyond the facilities available to home constructors as it invariably uses tiny complex components that can only be assembled into circuits using automated production machines. 2.4GHz is derived from Bluetooth and Wi-Fi and at these high frequencies there is little latitude for inaccuracies in the physical aspects of assemblies.

Hi, I don’t normally contribute to forums but this topic kicked off a nostalgia element in me. As mentioned in previous posts, I was the designer of the ‘Microtrol’ system, published in book form by Radio Modeller. ‘Theory and Practice of Model Radio Control’ first came out in 1972. Two further editions followed, the content being updated to reflect the technical advances of the decade. All the equipment was on 27MHz and used AM (amplitude modulation) for the radio transmission. Around 1979 we gained 35MHz for aircraft use and closer spaced channels. This was partly due to the adoption of FM (frequency modulation) for the transmission. A new ‘Microtrol’ system was developed and a complete revision and re-titled book was published in 1982 ‘Radio Control – a handbook of theory and practice’. Several things happened around this time. Japanese designed equipment started to become available at prices that became competitive with home construction kits. The hobby trade adopted a technical approval procedure to protect the integrity of our frequency usage – an early version of the concept now represented by CE marking. Radio Modeller magazine (but not the books) was sold to the publishers of RCM&E. All in all the wrong timing for bringing out the new book for home constructed equipment! My own career developed into specialising in the adoption of microprocessors for industrial electronics and modelling related activities took a back seat until around 1995.  At this stage I constructed a computerised transmitter, still christened ‘Microtrol’ and utilising the transmission module from the 1982 book as it had passed the hobby trade approval process. Another upgraded computerised transmitter was designed and constructed around 2006, still using the same 35MHz module. For a long time my flying interest had been electric launched thermal soaring gliders and in 2009 I started to fly competitively in national and international competitions. This very much coincided with 2.4GHz coming in and I bought my first ever commercial RC outfit, a JR.   More recently this has been replaced with a latest state of the art top end commercial product. What can I say, modern servos have so much more precision than what we had in the earlier times. The transmitter/receiver system has a matching precision in the handling of the control commands and the integrity of the radio communication link is something we could never have imagined in the days when I first began designing equipment. I am still a very active flyer and take to the air regularly with a type of model where the precision of the control equipment can really be appreciated. Every time I take to the air, it brings home to me just how much we have progressed over the past 50 years. It was exciting to have contributed a small part of it. Edited By Paul Newell 2 on 11/12/2020 18:17:07 Edited By Paul Newell 2 on 11/12/2020 18:19:11

Used to fly flat field gliders in the Thames Valley with the late Dick Edmonds. One day we watched a red kite pick up the bungee parachute and proceed to climb away until the tension came on. It wrestled with it, gaining more height for a while. Eventually the tension became too much - the ping off the top when the line released must have exceeded any thermal climb the red kite had previously experienced!

It is clear from his original post that Bert has a JR DSX9 MkII Tx and is looking for a compatible Rx. To avoid confusion, the JR DSX9 does not operate JR DMSS receivers. JR DSX9 Mk I, and Mk II Txs employ DSM2, the original Spektrum protocol. Subject to my posting above, Spektrum DSMX receivers are downward compatible with DSM2 so Bert has a wide choice of receivers available. I operate AR6260 AR8000 receivers with both JR DSX9 Mk I and Mk II Txs           Edited By Paul Newell 2 on 24/02/2015 16:55:57 Edited By Paul Newell 2 on 24/02/2015 16:56:50

The DSX9 is DSM2 protocol. As far as I am aware Spektrum DSMX receivers still support DSM2 so can be used. It may be worth a check with Horizon Hobby that the receivers still do support DSM2. Reason for this is that under recently introduced European Regulation the DSM2 protocol is no longer permitted for newly sold transmitters. Provided Spektrum have not changed the receivers there should be no problem. I use this Tx, with amongst others, the AR6260 receiver. Don't necessarily expect to get the Spektrum quoted range check distance with the button pressed on the TX - the power output in range check mode is different to a Spektrum Tx.

Issue resolved Contrary to the information gleaned from the web search, the system does use ppm transfer. Ring 2 is an input that accepts the ppm signal form the other transmitter. The cable requires a crossover so that tip connects to Ring 2 in both directions. This does not seem to correspond to any available Audio Visual cables. However there is a special E Flite cable which is not mentioned in any documentation for the transmitters and proved elusive in any web search until the part number EFLH1059 was known.

Has anyone used a trainer lead on the LP5DSM TXs that came with the Blade CX2 Helicopters. It is a FOUR way 3.5mm jack similar to used by some audio visual equipment. There are various forum postings elsewhere that relate to using one LP5DSM with say Spektrum or simulators. These do involve special connections. My problem is that a proper 4 way lead with one to one connections does not function. The Trainer switches do not switch control. I have verified (internally in the TX) that the lead is making proper electrical connection in the jack sockets and that there are no shorts between the 4 poles. As far as I can determine the jack has the following signals. Tip - negative going ppm signal Ring 1 - Power positive Ring 2 - ????? Sleeve - Power negative. A web search suggests the Ring 2 is an encoded signal that should provide the trainer signal between the LP5DSM TXs and that it does not use the more normal method of ppm handover. Electrically it certainly looks like a semiconductor device input connection. However it does not seem to show any form of data. Just a warning - don't go plugging a mono or stereo 3.5 mm jack into the socket as there is a risk of shorting power positive and negative.

I was recently asked whether there are any potential problems for persons who have a heart pacemaker, either as a pilot or as an observer on the flight line. (I could understand that the answer might be different between35Mhz and 2.4Ghz equipment). Anyone got any knowledge or experience of this? Edited By Paul Newell 2 on 07/03/2013 09:35:10

I spray paint using Halfords car paints both aerosol and mixed at the counter varieties. Have always avoided mettallic paints but pearlescent ones usually have a mica fill to produce the effect. This does not cause me any problems with Spektrum receivers, aerials inside fuselages, in eSoaring models. With this type of model we fly at long distances and sometimes very high.

Done some digging around for more information. Different receivers can have different protocols for the transmitted data stream, depending on such things as system resolution and perhaps telemetry requirements. The Tx does learn something about theRx during binding so that it can transmit the subsequent control data in the correct format. I would conclude that if different part numberreceivers are using the same protocol, they can be bound to the same model program. However if they have differing protocols, for a given model program the Tx will transmit its data in the format appropriate to the most recently bound Rx. In the case of large models reqiring two receivers, it should be OK if they are of the same type.

I have definitely read somewhere about the Tx learning the receiver type during binding and with my JR DSX9 have experienced this with AR6100 AR6255 and AR7600 receivers. Just which characterisitics of the receiver are involved I do not know. I have certainly deliberately bound more than one of the now obsolete AR6250 receivers to the same model program and havedefinitely been unable to operate an AR6255 and AR7600 off the same model program at the same time. This is something totally separate from model match which operates to stop a different model program being selected to the one that was used to bind a receiver.

With DSM2 systems with you must be careful when binding more than one receiver to a given model program.  During binding the TRANSMITTER learns the TYPE of receiver to which it is bound.  So you can bind two models to the same program if identical receiver types are being used but not if using different receiver types.   If you get it mixed the Tx will only work on the given model program with the last receiver to which it was bound.   Model match is different.  This is where the RECEIVER learns the model program number  to which it is assigned.

Peter,   The example I quoted of a Graupner crystal in a Futaba compaitible cicuit is an extreme case.   However crystal specifications involve a lot more than just the frequency.  In a 35MHz  transmitter the frequency is moved either side of the centre frequency to produce the FM signal modulation.  One way of achieving this is to vary the capacitance of the oscillation circuit as seen by the crystal.  Obviously the amount of this frequency variation is such that it remains acceptable to the receiver.  Just as important is that is does not stray into the 'seeing window' of a receiver on a different channel.   Using an incorrect receiver crystal can affect both thecentre frequency AND the amount it changes with the modulation.  This can cause a whole range of problems some of which may not be evident with a range check or even in flight. Some of these are as follows.   Occasional glitches, posssibly at only certain battery voltages.   Reduced range.   Interference with other users on adjacent channels.   Interference with other users on channels elsewhere in the band  (due to various combinations of harmonics - too complex to explain on this forum).   Might work trouble free with one receiver and not another, either same or different receiver manufacture.   At the end of the day everything is designed to work within a specification with a little bit  of safety margin.  If you change something that takes part of the system to the edge of the specification you erode the safety margin and one day it turns around and bites you OR SOMEONE ELSE.!    

To the best of my knowledge Futaba and Fleet single conversion crystals are the same spec.  As the designer of the Microtrol system published by Radio Modeller back in the distant past, either could be used in my design..  Whilst the TX6EAP could well have a different form of RF circuit to earlier designs it is unlikely that Futaba would have changed the spec of the crystals.   It is all to do with the harmonics but also the nature of the capacitance of the circuit into which the crystal is inserted. - i have some Graupner crystals which worked OK in my circuit BUT produced the signal at a frequency midway between two official channels.  This is why it is stated only to use the manufacturers crystal in a given transmitter. Receiver crystals are different and far less critical.