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Old Sep 05, 2015, 06:14 PM
Mad Man Marko is offline
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New electronics in vintage radio transmitters

I have a few old EK champion and Hobby Lobby 5 transmitters and would like to add Spektrum electronics internally but still use the EK tx and sticks. Does anyone know the value of the pots for the EK sticks and trim pots and if they would interface with the spectrum encoder circuitry.
Thanks
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Old Sep 05, 2015, 08:30 PM
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Don't know specifically about the EK/Hobby Lobby variety, but most of the transmitters from Kraft/Heathkit systems of that era (looking at the old schematics) were 5K mains, and 50K or 47K trims. Best to grab a VOM and test across the two outer leads to make sure, though.

You using a modern encoder, or are you planning to adapt an older encoder to 2.4 GHz?
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Old Sep 05, 2015, 08:57 PM
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New electronics in older transmitters

I was thinking of using the entire encoder and RF circuit from the 2.4 Ghz Spectrum just use the old sticks and case.
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Old Sep 05, 2015, 09:54 PM
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I had Radio South (now in Muncie) help me with the conversion of some old Kraft TXs to 2.4.

I've been using these after giving up on Spektrum a few years ago and haven't had any issues.
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Old Sep 06, 2015, 08:30 PM
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Quote:
Originally Posted by Mad Man Marko View Post
I have a few old EK champion and Hobby Lobby 5 transmitters and would like to add Spektrum electronics internally but still use the EK tx and sticks. Does anyone know the value of the pots for the EK sticks and trim pots and if they would interface with the spectrum encoder circuitry.
The resistance of the pots doesn't matter so much. We use 5K pots in the radios. What matters is the range over which they travel. If they don't go close-enough to the 0V and 3V values, they won't be able to calibrate.

Andy
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Old Sep 20, 2015, 06:09 PM
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Hi,
Another option is to get an Arduino encoder from Phil Green.
At singlechannel.uk. He can program them for you either forAETR or TEAR. He also can deliver you a PCB to mount the Arduino on. But it is easy to make you board yourself. That encoder gives you up to 7 channels, DR and EX. Only one model memory, and also Single channel emulation. You have to tell him what DIY RF module you want to use. To much info to tell here. Any questions, you are welcome.
Regards,
Pat
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Old Sep 20, 2015, 06:12 PM
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Some more pics. This one is working with FrSKY, in 26 hours of flight never had one glitch. Range is plenty, at least for my eyes. I also have a reed transmitter working on Spectrum/OR RF module with Spectrum receivers.
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Last edited by PAT-T; Sep 20, 2015 at 06:17 PM.
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Old Sep 20, 2015, 06:25 PM
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http://www.modelflying.co.uk/forums/...s.asp?th=97589

I just visited Phil's thread, and recently it is even more simple to get an Arduino in your TX.

So I'm guessing this will be the standard PCB for retro-refits now, and I've updated the "7ch + S/C mix encoder" document to include this board, its item P16 on the Archive page of www.singlechannel.co.uk

You can email Phil Green at philg@talk21.com

Regards
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Last edited by PAT-T; Sep 20, 2015 at 06:38 PM.
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Old Sep 20, 2015, 06:42 PM
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Last available version from Phil.
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