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Jan 09, 2013, 10:27 PM
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Thanks Vince.
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Jan 26, 2013, 12:50 AM
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Hi .
I bought a transmitter said to be a Royal Classic. I do not think so . Maybe it is a World Engines MAN 123.
Please help me.
Jan 26, 2013, 10:34 AM
AndyKunz's Avatar
That is VERY clean inside! The many radios of that era that I have were all filthy when I got them, and some were nearly impossible to clean (so I didn't)

Jan 26, 2013, 07:20 PM
Registered User
Is there someone out there who can suport me with an electrical scheme for what I think is a M.A.N.123 transmitter.
Jan 26, 2013, 10:59 PM
Registered User
I think you do have a Royal "Tech RC" single stick TX. It should have a silver vinyl case. Royal Electronics built radios under the Royal name (blue vinyl cases) and sold kits you soldered up your self under the "Tech RC" name (brushed silver vinyl). Yours is missing the Tech RC logo / name plate.

The encoder board is exactly the same as some Royal systems I built in the 70's and early 80's. Wire colors are standard Royal and the meter is the same as used on Royal systems

Your RF deck is a Royal TX deck designed by some Lockheed RF engineers in Denver for Royal Electronics. That RF deck could be assembled to operate on 27, 50, 72 and 75 MHz. Only the 50 MHZ RF deck was shipped unassembled.

The TX was designed to be powered by 5 (6 volts)1.2 amp sub C Ni-cads because AA ni-cads were in short supply / expensive in that era.

Seems yours has had a PL-256?? connector added. Original TX would have a short white wire to the antenna base.

Sid Gates, the founder of Royal Electronics, was an Air Force fighter pilot that started Royal Electronics in Denver CO. I recently had contact with Sid and he is still actively flying RC including turbines. Unlike some in the hobby industry Sid was always a soft spoken gentleman doing what was best for model aviation. As the owner of a local hobby shop I assembled about 150 Tech RC kits and sold them to local RC fliers. The equipment was reliable, a few are still in use locally today. I have converted a few to FrSky 2.4 GHz using the DTH-U module that adds full telemetry.

Toward the end of production I designed and produced an 5044 replacement encoder that added servo reversing and the ability to do simple mixing for any of the Royal systems.

I have a complete set of schematics for all the Royal / Tech RC transmitters & receivers. Can scan some for you if you like. Any technical help I can give you I will. I have several still working that I could fire up. IIRC the encoder schematics have several scope pictures on them of the encoder running. I may have a replacement name plate if I can find them.

I am really curious how the TX got to the Philippines, I would guess by US military serving there.
Last edited by Hugh P; Jan 26, 2013 at 11:10 PM.
Jan 27, 2013, 05:35 AM
Registered User
Hi,I think you are wright. It is exactly as you say. I am not sure about the Vinylcovering as it looks like brusched aluminium. The antenna is a very nice thing and it uses a 6 volt pover battery. I have just bought it on e-bay to the Philippines. I am 73 years old and when I started flying there were just singlestick tran1smitters. I plan to rebuild it to fr-sky with a hack-modul as you can se. I have rebuilt 2 JR Centery and one Orbit but in this case I am a little confused. I have never seen such a RF deck. There are some realy odd things there. I would be very glad if you could help me out. And if you find the nameplate maybe I can by one to make the transmitter perfect.
I am from Sweden but now I am retired and newly remarried with a Philippina and spend the cold wether in the winter in Philippines.
Jan 27, 2013, 09:42 PM
Registered User
If I recall the story about the RF deck correctly there were some Lockheed Missile division engineers that designed the actual RF deck for Royal. These Lockheed employes were active RC flyers and this TX deck was the second RF deck that Royal used.

The first transmitter that Royal designed was the "purple box TX" with a single PCB for the encoder and 27 MHz transmitter. IIRC the encoder had a unjunction oscillator. The antenna was center loaded. Kraft stick assemblies were used.

If you look at the RF deck in your TX you will find three TO-92 transistors lined up in a row. These are the final output amplifier, only RC RF deck I have ever seen designed that way.

I have had many of these RF decks on a Tektronics 7000 scope and a Tek 7L13 spectrum analyzer and they are very clean and narrow band, way before we started narrow banding our equipment in the USA. Sid commented one time that it was way over designed but what did you expect from some guys designing missiles for fighter aircraft weapons.

The receivers were a very conventional super het design of 6 or 8 channel with 74LS15 decoder. Range of the system was never a problem.

Late in the life of the company Royal produced the "Omega 7" channel TX with mixes, expo, cross trims, etc. Probably the most sophisticated TX built before computerized designs. The Omega was also produced as a twin engine TX with separate throttle trims active below half throttle.

The Omega 7 PCB and schematics are available for download at

I will try to get the instructions for your TX scanned and uploaded in the next day or two. The Tech RC systems were shipped with Heath Kit like construction instruction and full schematics.
Jan 28, 2013, 09:23 PM
Registered User
.I have taken the RF-deck out. It is marked with R 460-T and the crystal is 26 510. I can see the 3 transistors you were taking about. They are in paralell and thats strange. What I have never seen before are the small coils on something looking like Ferrit.
Before I retired I had a small hobbyshop importing and selling modelkits in Sweden. I also helpt some modelengineproducer with some designing. I made the Irvine engines dieselengines and even the Laser-engine 4-stroke-diesel engine. In Sweden I was behind the first Gasturbine for modelflying, the Turbomin 80 and Turbomin100. Remotecontrol equipment was just bought when I did need them. Now I am more interested in using vintage-radios to fly vintage-models. As I told you earlier I started with SingleStick and now Im back to that as it fits me better then the 2-stick. My first singlestick was the Quadroplex 21. Now I use the JR Centary 7 channel and one old Orbit. Will be nice to fly with the Royal Tech RC.
Jan 29, 2013, 09:44 AM
AndyKunz's Avatar

I know one fellow who still flies with old radios who may be able to help you. He goes by the name "Taurus Flyer" on RCG. He's Dutch, which probably explains why he never bought a newer radio He's active on RCU with the same name.

He's a very helpful soul.

Jan 29, 2013, 05:30 PM
Registered User
Does a HeathKit R/C system Model # GDA-19-1 have any value?
Includes Transmitter (72.400 MHz), Receiver, on/off switch, 4 servos..and charging cord.(both Tx and Rx battery packs must be replaced.)
Also Futaba R/C system Model FP-T6FN with 4 servos, charging block, Tx, Rx
Jan 29, 2013, 05:49 PM
AndyKunz's Avatar
Collectors on ebay will likely be interested.

Jan 29, 2013, 10:35 PM
Registered User
After trying to install the Assan system without any success I went over to Fr-Sky. First test and now it works. Royal Tech RC with Fr-Skt is a success.
Next try is Heathkit GDA-405 Single-Stick. I have 3 of them.
Jan 31, 2013, 02:07 PM
Registered User
Thomas, how's the R/C flying in the Philippines? I heard of a club near the old Clark base, but not much else.
Feb 01, 2013, 08:14 AM
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JMP_blackfoot's Avatar
Originally Posted by Hugh P
...If you look at the RF deck in your TX you will find three TO-92 transistors lined up in a row. These are the final output amplifier, only RC RF deck I have ever seen designed that way...
Here is a Becker 4-channel "calculator-sized" transmitter I converted to FrSky 2.4 Ghz after long trouble-free usage on 41 MHz.The RF power amplifier stage also uses three parallel transistors and the battery is a 6-cell 600 mAh Nicad. RF power on 41 MHz was high, never a range problem either.
Feb 01, 2013, 09:49 AM
Registered User
Sanwa's (aka Airtronics) first (award winning) radio:

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