doxilia

My Feedback: (3)

Double post.

jazzboy

My Feedback: (1)

You cats are going hog-wild! Excellent and keep up the enthusiasm. Just spotted hits on my blog from this thread and wanted to send my compliments after reading some great discussions

I will be wiring another MS2K in a few days. Would the ppm to mini plug/serial interface wiring photos be helpful?

Great work David!

Cheers,
Andy

doxilia

My Feedback: (3)

Mike,

in that case, Kraft must have had other plans for that Tx connector beside the Rx battery voltage cable. I guess I'll have to make myself one of those two lead cables to check whether that functionality works with my 7C encoder. I have some extra chargers that have these connectors so it should be doable.

I'm starting to wonder if the DSC module could also be plugged into the trainer/charge DIN jack of the Tx and drove the servos over a 4 pin cable to the Kraft 7C Rx power harness. As you can see, the cable leads on the 4 pin connector on the Tx use the same colour coding as the leads on the trainer jack (yellow/red & orange/black). It would be great if you were able to take a picture of the relevant pages of the manual. A manual scan would be fantastic since I would like to add the D/R, roll button features to the Tx.

So did the DSC box only allow throttle and retract operation or other channels too? If there was a Mode 1|2 switch, did that allow you to control elevator by using the "incorrect" mode?

On JR systems of the 80's, that's exactly how DSC worked. Upon plugging in a 1/8" mini jack to the Tx and the other end to the charge receptacle of the model, the encoder powered up but the RF remained off. Of course this is also how the trainer system worked. The two Tx's would interconnect with a 1/8" jack cable which powered up the slave Tx encoder and simultaneously passed PPM voltage levels over the tip of the 1/8" jack. I guess it used a shunting system of sorts. The jack acted to jumper power to the encoder and then PPM was output over the simple cable. Note that the 1/8" jack was mono not stereo so only one signal could go over it!

I did trace back the leads from the 4 pin plug. They go to the front right pins on the encoder, right beside the leads that go from the encoder to the RF deck. I didn't take pictures of the back of the PCB (my bad) so I don't know for certain but it seemed plausible that these same colour leads might have been jumpered via the PCB which is why I assumed that PPM voltage levels might have been present on two of the four pins to drive the Rx in DSC mode.

On the other hand, it is possible that these four pin plugs were all wired the same and used for all 7C's and maybe even 5C's including the PK Signature Series. Maybe the SS Tx's and Rx's contained logic that allowed a full DSC function over a four pin cable. The 1979 and later SS Tx had ATV, servo reversing, expo and other features adjustable via a removable panel where the typical Kraft logo is usually located. The SS radios came with your name embossed on them... [8D]

Whatever the case, none of the leads at the jack have any voltage level in stand alone mode (i.e., nothing plugged into the trainer/charge DIN jack) so perhaps they are only input leads on this Tx model.

David

doxilia

My Feedback: (3)

Oh yeaaa... I have questions for you Andy but as you have said before, a picture is worth 1000 words! A few pics would cut down considerable typing!

The MS2K schematic has J7 pins 3&4 for the buddy box function with Tx/Rx serial interconnect via the IC3 chip. Are these actually PPM level signals though? I wouldn't have thought so. They "read" like additional communication ports just like those for the "PC interface" for programming the encoder. J7P5 appears to be unwired but is marked MOD. Is this actually the PPM output for simulator interface along with P6-ground?

I guess I did ask the questions...

How's that Proline coming along?

Thanks for the encouragement - just trying to learn the ropes.

David.

jazzboy

My Feedback: (1)

J7 pins 5&6 are used for my sim output and it works perfectly with Phoenix. There is another ppm available on 63/64 (can be switched to ppm in software) but the voltage was too low for the Phoenix interface (works on those cheap usb interfaces with free sims). J6/rf interface was used to feed the rf module.

On the Kraft I used pins pins 1 and 2 from J7 for serial db9 plug and shared ground (pin 6)  for ppm and serial connections. I added a 120ohm resistor on the + ppm line and a 100ohm resistor on the -ppm lines for protection.

Keep the builds going!
Andy

jazzboy

My Feedback: (1)

btw, my photos of the silver MS2K show pins 63/64 being used for sim. This was prior to Phoenix and is not recommended. I will get those new snaps soon.

andy

BelAirBob

I have an Orbit single stick of the same era, and a two stick Kraft 74. I really liked the single stick, especially with sail planes. I always thought the transmitter was easier to hold cradling it..... If anyone finds a way to modernize the Orbit, please let me know. I remember my Kraft Series 74 was $399.95. I got it at Skelly;s in York, PA as a college graduation present to myself.

bob

8178

My Feedback: (17)

David,

From what I’ve read in my manual the direct controller had one function lever (pot) for control. A switch was used to switch the control between retract and throttle. Expect they had to have a mode 1 and 2 switch on the box because back in those days the throttle and elevator were in a fixed position in the frame of pulses, e.g. the mode change was just a mechanical change in the stick assemblies.

My ohm meter is showing that the two unused pins are jumpered together in the TX side of the cable plug. Maybe the extra two pins are used in conjunction with a jumper in the plug to change the scale on the volt meter when the RX battery is measured. There is a 9.6 scale and 4.8 scale on the same meter face.

Phil has got to be smiling down on us!!!

doxilia

My Feedback: (3)

Right, makes sense.

Mike, does the Tx have to be on for the Rx voltage to be displayed?

He's probably rolling over on his stomach!

8178

My Feedback: (17)

David,

The RX batteries are checked with the TX off.

Prairie Mike

David & Bruce,
Thank you for the answers to my questions.

I opened the battery case and found several of the cells had vented. According to the repair sticker inside the case, they were changed in 1980.
That's a little long for my comfort level since I usually change all my batts within a 4 year time frame. I plan on using the standard JR Tx battery pack which you can buy in any well stocked LHS and the size works well for the Kraft case.

I have the microstar encoder and I guess the only disappointment would be that I won't be able to use digital trims. At least by keeping the trim switches in the same location. But that's not all bad since analog trims are fine as is. If I used digital trims the base of the rocker switch would interfer with the stick pots. Of course I could change location, but having autotrim why bother. Besides I am comfortable with the present switch/trim lever locations.
Using the old encoder would be a waste of time since it didn't have all the neat stuff I use at present like dual rates and especially, exponential.
I was looking for something about exponential and reread the PDF on the system and then realized that the expo features are a mirror of the dual rate setup. Wow! How easy is that!

So if David is gonna start a build thread about his Kraft conversion, I'll build along with him.

doxilia

My Feedback: (3)

Mike,

You can use digital trims. Take a look at post #1 for how I plan to do this. Actually, trims for aileron and elevator are almost not needed. Trims for rudder and throttle are still convenient, especially on a single stick.

Regarding your encoder, is it built or in kit form still? Either way, some pics of it would be interesting to see. Is it a recent encoder or an earlier v3 or earlier encoder?

Also, a standard square 9.6V Tx pack is not ideally suited when converting to MS2K. When I get to it, you'll see why. We need to use either 1500 4.8V packs (2 of them) or a flat 9.6V pack. The LiFe packs might be ideally suited for these small Kraft cases.

What do you want to use for RF deck?

David.

doxilia

My Feedback: (3)

I should have phrased that previous post a little better.

Because the gimbal has four pots surrounding it, installing rocker switches where the current levers are located does present a problem. However, only two of those pots need to remain there, the ones for the main controls: aileron and elevator. The other two pots are strictly rudder and throttle trim pots and can be removed. Unfortunately I started posting shots of the radio disassembly in another thread but eventually I'll get back to that with photos here. In short, the rudder and throttle trim assemblies can be removed from the gimbal and so can the trim levers from the master aileron and elevator pots. This leaves two areas around the gimbal pot free where digital rocker trim switches can be installed.

Unfortunately, the other two trims cannot be located where the originals but locating them elsewhere is not a bad alternative. I actually think I prefer the rudder trim where my left thumb can reach it atop the Tx centered on the gimbal assembly. For the throttle, trim is useful for the initial setup but may not be needed much after that with the presence of the throttle preset button. Because of this, I located it in the area where the left index finger can reach it near the actual throttle lever.

In the case of later SS Kraft radios, the elevator pot is actually centered within the gimbal rather than on the side so one ends up having three usable spaces for d-trims. Andy Horka converted such a Kraft radio and the d-trims are located left (elevator), bottom (aileron) and right (throttle) of the stick. The stick was rotated 180 degrees to position the aileron pot toward the top of the case.

David.

hook57

My Feedback: (21)

David,
You might want to consider the Xtreme Power Systems (XPS) universal deck also.It doesn't care about shift either (I use the same module/deck in both the Kraft and the Pro-Line). You can use it with any of their Rxs including the Nano and park flyer versions. It's a breeze to hook up (made in America too). Not as cheap a the FrySky, but I think many more in use than the former one. The yellow wire on the 7C should be the ppm signal, red is v+, black is Gnd, I pulled the rf deck out of the Tx along with the antenna and will mount the deck inside with access to the bind button and the status light. Keep it simple!
Mark

ps: Found this, thoughtit might be useful.

doxilia

My Feedback: (3)

Thanks Mark. I began by considering all the alternatives particularly with respect to the 2.4 implementation of the manufacturer. I have been using DSM2 since I switched from FM (never did use PCM). I haven't tried any other 2.4 radios other than DSM2 and was intrigued by the frequency hopping approach which is clearly considered to be robust by many modelers, not only those using them to fly but also electrical engineers who are testing them. Of the low cost 2.4 alternatives, FrSky has stood out in many respects. While not infallible (I don't think there is any manufacturer who can claim that yet), it appears to be a solid system which is fast, robust, flexible, offers good service (for an overseas company) and is low cost. While I don't plan to convert these projects to FrSky exclusively, I will give it a shot on one or two of these vintage Kraft's. There are also practical reasons to use them as they offer a module (actually two - the hack modules) that is conceived for a conversion project.

Yup, the schematic confirms this too. I started to think about the 7C's plastic RF deck and antenna housing. I was wondering if the 2.4 deck PCB's would be small enough to fit inside the original Kraft AM/FM deck module cases (or the case Tx housing). The AM cases are pretty small and 2.4 decks use largish IC's (at least Spektrum does). The FrSky modules however appear to be smaller with a 43 x 34 mm PCB but the Kraft RF receptacle is only about 40 x 30 mm - just shy of what's needed. Have you found a way to use the plastic housing to advantage with the the 2.4 XPS decks?

David.

hook57

My Feedback: (21)

It will be good to see a 2.4 FrySky in an old Kraft anyhow, and I've seen that it is a pretty simple hack so I eagerly await its completion (I may just performit on oneofmine too). Regarding the module housings, no; my plan is to employ stand-offs or fab a plastic clip (using small plastic C channel) to hold the module inside the Tx. I'll run the antenna cable to the antenna in some small teflon sleeve and have an access hole (or two) for the bind button and the status light. The alternative is to use two-sided tape to hold a universal (XPS) module inplace on top of the TX. You don't have this available with the DSM2 module. You could find/buy an empty module case (I think XPS sells them) and fit it into it to mount on the Tx exterior. Youmay have to cut the recess in the module to fit the board, butI know from experience that the DSM2 and XPS boards are very similar in size in that respect. That's all just an idea, the more we have the more succesfull we'll be, all told.

Mark

AndyKunz

Mark,

What do you see as the limitation of the Spektrum module? They can be removed from cases and mounted internally in the transmitter - in fact, you can see that's exactly what I did with the GWS conversion I did for my daughter.

Andy

doxilia

My Feedback: (3)

Michael was kind enough to post a PDF of the encoder schematics for the Kraft KPT-5C (same schematic and board used for the 3 channel radios too) and 7C - single and dual stick. The SS and DS schematics are the same with the appropriate comments where they differ. The file was posted in the Kraft Conversion thread so I'll re-post them here for reference.

After going through them in some detail (not all is clear since the function of IC2 is simply shown as an amplifying section), I've learned a couple of things. First, Kraft is mostly consistent with wiring colour so that a given wire colour used in one place is actually used again for the same purpose when joining other two components. Of interest is the orange/black wire used in the trainer jack which goes to the encoder and then is "plug jumpered" to the RF deck. It is now clear to me what this wire is used for in the 5 and 7 channel series radios.

JR/Spektrum's trainer system (which is very simple in terms of cabling using a mono mini jack) required the master Tx to be on (hence broadcasting) and the slave to be off (and have the encoder powered up by the trainer plug acting as an "encoder switch" as well as for PPM transfer). This allowed the slaves encoder to pass on PPM signals to the master which were routed to its RF deck while the trainer switch was activated. In Kraft's trainer system, both Tx's are turned on. This avoids having to build in a system which triggers power to the slave encoder when in trainer mode via the cable. However, while the slave Tx is on, it also is broadcasting over it's RF deck which is undesirable - especially if both master and slave Tx's are on the same frequency (unlikely but could happen). In order to shut down the slave RF deck, power to it is shunted via a resistor to a low voltage level with the aid of the orange/black wire which is shorted to ground within the trainer cable plug (see first picture).

Before getting into the PPM routing, a few other points are worth mentioning. Referring to the 7C schematic (picture 3 below), the main encoder amplifier section is in the top left of the drawing. The pot logic and multiplexing is in the lower half of the drawing with the upper right being the various components and interface logic to the encoder circuitry. This includes the trainer, charge, batteries, Rx battery voltage, RF and V meters and RF deck interfaces. The Rx voltage plug, J2, that Mike and I were discussing (with respect to its four rather than two connectors), contains what I believe is a zener diode load circuit (just to the left of P6) to simulate working conditions on the Rx battery and to provide a "voltage multiplier" for proper display on the Tx voltmeter. The battery voltage is passed to the connector via the red and orange leads which are routed through the load circuit. The red and yellow/red lead connectors must be shorted at the Tx plug end as are the orange and black (ground) connectors. The yellow/red wire then passes the loaded voltage over to the voltmeter via the jumpered wire on P6

Now, as for the routing of PPM signals via the trainer system, again Kraft used sensible wire colour coding choices. The two wires involved in the PPM path are the yellow/red (I'll call this PPM Rcv) and the grey/white (I'll call this PPM Snd). The following is a little tricky to phrase so please bear with me. I'll describe the PPM path using only one Tx in slave and then in master mode as the paths differ.

When a Tx is in a trainer setup and used as the slave, the trainer switch is not depressed on it and is in its normally closed (NC) position. If one refers to the 7C schematic, we can see that this routes PPM voltage levels through the blue/black trainer wire which in turn routes them through RFC2 (22 uH) to the grey/white wire on both P4 and the trainer/charge DIN jack, J1. So the grey/white wire provides the PPM Snd signal to the master Tx when used as the slave. Now, the trainer cable has the grey/white wire (pin 3) at the slave end connected to the yellow/red wire (pin 1) at the master end. Since the master Tx has the trainer switch depressed in the normally open (NO) position, the signal is now routed through RFC1 (also 22 uH) via the grey/white trainer switch wire to the blue/black center switch wire (shown at the top of the switch on P5 - the trainer switch encoder PCB plug) and finally back to the PPM yellow RF deck lead on P3.

I'll post the pictures and continue later as I have to make an appointment. The PDF of the document Michael provided is also attached for better clarity in referring to the encoders.

David.

doxilia

My Feedback: (3)

Mark,

I was going to ask the same thing as Andy. Why are you bothering with the module cases if all you need is the RF deck PCB for an internal mount. In my first post, I drew the Spektrum RF deck (outside of its case) to proper dimensions showing the location of the bind and status LED lights. The deck can be mounted inside with some standoffs to the front of the case. The bind button would protrude from the front of the case (just like it does in its module case) via a small hole. The LED would be behind another small hole so one can see it.

With the "hack" modules, they have a separate little PCB with the bind button and LED. This allows them to be mounted separate from the RF deck itself anywhere in the case where convenient. If it is possible to install the 2.4 antenna where the original FM antenna was in the 7C (part of the AM module housing), I may locate this little bind button/LED PCB where the AM deck top lid used to be. A sensible place it seems to me. If the housing can't be used, then it will still be located there as there will be the opening in the case where the RF deck used to enter the case.

David.

hook57

My Feedback: (21)

David (and Andy)
Wow, I have to come up for air! Youare both right, I must have got two thoughts combined. I had looked at putting the DSM2 board in a spare JR module case because the DM9 module did not fit snugly enough in the C7 Tx (we discussed that earlier). My brain must've jumped a track when I was reading the thread, sorry about that. The universal XPS module I have gets used onboth theKraft and the Pro-Line Txs'. Although, some have taken the module case and placed it inside of the TX (http://www.mindspring.com/~rellis2/rcpattrn/retro.htm), one isan old Kraft, but not 2.4.
I do like the idea of placing the bind button/LCD PCB where the AM lid was. Did you pick up the FrSky module and Rx yet? Again, sorry about the confusion there.
Mark

Prairie Mike

David,
I tried one of my Tx battery packs (JR) see what you were talking about. I also noticed that you can't use the Kraft battery box since it'll interfere with the LCD placement.
My original thought was to use a module (Hack or Futaba) and thought it would provide more room in the Tx . I have since ordered the non-case unit you were telling me about. Looks like I can use the original antenna hole for the 2.4 antenna.
I really like your placement for the rudder and throttle trim switches.

1. What are you doing about the left over holes/slot in the case?
2. What do you plan to use to fill them?
3. Any ideas of what to use to duplicate the vinyl Tx covering?

I saw the list of components you asked Andy about in your other thread. You stated "Active" for the switches. Did you meant "Action Electronics"? Since they shut down, I've located another source for the rocker trim switches.

You're right, there isn't much room in the Kraft case and I'm not sure where I'll locate the RF board. Think I’ll use your idea for the LCD. I don't want to go LiPo, don't like the self-discharge of the NiMh, so I will probably stay with NiCads. Just not sure where to put 'em


PM me with your list and source of pots, switches, dress nuts, cabling etc., and I'll try to make up a source list to post here.


Unfortunately, my digital camera shot craps and I won't be able to post pics until the new arrives. I have the 12 bit encoder board. I just got that from Kees about a week ago.
By the way, he doesn’t have the USB cables any more but you vcan get them off Ebay. Mine was 99¢ plus 2.95 shipping.

I'll hold off on my photo/build ‘til the new camera gets here. Naturally, it's back ordered.

doxilia

My Feedback: (3)

Mark,

no worries regarding the RF deck question. It was really just to point out that you can install a dedicated module internally without the case if you want to do so. Omitting the case, makes for slightly easier planning in the smaller cases. Of course, if you want to use a single RF deck in 2 or 3 Tx's then planning things around a plug-in module case makes sense. With the low cost of the hack modules, I figured it was easier to make it part of the rebuild and just leave it inside. This also makes for a clean Tx back that in the absence of a stand, I like to have. I'm not thrilled about the idea of resting Tx's on their antenna connection which is what happens with some of the external module cases.

I haven't ordered the decks yet but probably will soon. They can take a while to arrive if they are coming from across the pond, but I'm in no rush.

David.

doxilia

My Feedback: (3)

Mike, the original sub-C plastic battery cases made sense with the original encoders and decks but they do take up a great deal of space. Installing the MS2K encoder vertically (so that it faces you when the Tx is resting forward) makes it easier to access the various plug pins on the top (back) of the encoder. With the SS Tx's the gimbal is placed more toward the center of the case so I'm not sure if it's possible to install the LCD where the original RF meter was located. I have been told that it does fit but the question is which LCD. According to the dimensions of the LCD PCB provided by Kees on his web site, it appears that it won't fit in the upper left corner (when holding the Tx) but until I have it in hand to check, I won't know for sure.

If it doesn't fit, then the only other logical place to locate it is behind the Kraft label in the lower center of the case. If located there, then the encoder needs to be mounted in front of the LCD PCB which leaves less room behind it for any batteries. In short, between the various switches and pots that take up space inside the case, the encoder and RF deck, and the LCD PCB, there is little space to locate the batteries. If one were to use a square pack, it would use up more valuable space in the case. A flat 9.6V pack velcroed to the back lid of the case should fit where the power switches are located behind the RF deck as shown in the drawing. It also depends on what kind of a conversion one has in mind and how many switches, pushbuttons and channels you intend to make functional.

The caseless decks take up less space but they become more or less dedicated to the Tx. Note that even these decks though can be removed and used in another Tx provided you solder some connectors to the leads. One would need dedicated antennas and bind PCB's for each Tx though so one might as well make the deck dedicated to the radio. They are not very expensive.

I plan to do a dry mount of all the components making all the required holes. The drawing in post #1 shows what I think will be the unused holes in dotted lines (basically two trim slots). I will make use of the power switch hole and the trainer button hole as shown with other switches. I will then strip the vinyl from the case (it's not in great shape in my particular case) and fill the unused holes with JB Weld. I will then prime and paint the case giving it a textured finish.

The rocker trim switches are the trickiest to find in the required dimensions. Andy sourced some from a business called Active Electronics in Vancouver, BC. Digikey has what appears to be a suitable alternative. I am also considering using smaller rockers for the rudder and throttle to allow more space for the aileron pot and the elevator trim rocker. If you have another source for them, please do post the info.

Haven't made a list yet. I'll document it here when I get to it with part numbers and source.

I think my encoder kit might have just arrived today. I have to go to the PO to pick up a parcel. USB cables are also easy to source from scrap computer stores.

David.

doxilia

My Feedback: (3)

Double Post.

RCU seems to be double posting my replies if I edit them...

David.

Prairie Mike

David,
The switch Andy spec’d for me can be found at
Electronic Components & Equipment

Snap-in Rocker Switch
Part# : 35-695
SPDT (ON) OFF (ON)
http://www.ecemiami.com/shopdisplayp...tches%2FRocker
scroll down to 35-395
$3.95 ea.