Modern Equvalents for Kraft Servos

[Tosh McCaber]

Having come back into RC, I have a Kraft Series 70 RC radio, still in operation on three gliders. (OK- don't laugh!). The radio gear (with new batteries) and planes still perform perfectly, despite being between 45 and 55 years old. (One had Orbit RC equipment before the Kraft went in!)

However, having bought a Spektrum DX9 Tx, I' m thinking of upgrading these models to use some medium/ low priced servos now with the DX9.

Can anyone recommend modern general purpose servos of similar mounting dimensions to my old Kraft ones. (Hobby Lobby or?)

The Kraft servo dims are:

43.5mm long x 19.5mm wide

with mounting holes at 51.5mm o/c long x 10mm o/c width.

Also, it would be useful to know which receivers may be used with the DX( (not necessarily Spektrum, but I would like full range).

Any replies appreciated. 

[Denis Watkins]

Right hand bottom of this screen Tosh, is a column of suppliers

Click on airtek

Their servo list contains all dimensions of each servo

Spectrum works well with Spectrum Rx

But Lemon do some solid Rx with satellite from Inwood

And Orange too from rapidrc

Edited By Denis Watkins on 13/08/2018 20:58:25

[Paul Marsh]

For Spektrum radio, you should use only Spektrum receivers. I can see howls of derision coming from some, but the receivers are made for the radio. Using some other brands are less reliable than your 55 year old radio set!

Welcome back into rc - my how things have changed!

[Shaun Walsh]

Hi Tosh
Give Steve Webb models a call about the servo, also online as servo shop, they should be able to help.
Regarding receivers, if you only need up to 4 channels then spektrum aren't expensive and I recommend them. I have tried orange receivers from hobbyking but fried 2 by connecting them to a 2s lipo despite them being sold as suitable for the voltage, to be fair hobbyking gave me an immediate refund without asking for the receivers to be returned which makes me think its not an unknown problem.
I am currently using a 6 channel lemon receiver in a motor glider with flaps because it was easier to fit as it has end servo pins. It works fine with my spektrum dx6, but the diversity antennae are attached with micro din connectors which disconnect easily as I found out on the first range check when I got no further than 6 feet before everything went haywire, on checking both antennae had popped off, five minutes work with a hot melt glue gun sorted that out and range is at least as good as the spektrum equivalent.

[Shaun Walsh]

Also, those servo dimensions are pretty close to current standard size servos approx 40mmx 20mm with 10mm between fixing holes. Alternatively drop down to something smaller like the spektrum A5040 and add ply filler plates to the current mounts. I am refurbishing a 1970s Graupner Cumulus and was originally going to use standard servos but when i looked at the available space it was so much easier to fit smaller ones and they still have plenty of torque for the application. Unless you are very fortunate you will probably need to make new pushrods anyway so changing size shouldn't cause too much extra hassle, I replace my balsa pushrods with ones made from carbon fibre tube.

I read somewhere that Savox servos can sometimes cause brown outs with Spektrum receivers, don't know if this is an urban myth as I have only used Spektum servos.

[Nigel R]

Sound like standard size (about 40g) servos to me, too.

Hitec HS425BB would be top of my list.

http://airtekhobbies.com/hs425.html

"which receivers may be used with the DX"

Any Spektrum, but buy it from a proper shop, there are a ton of fakes around. Safest choice.

In a cheapie I have/would use again - Orange DSMX receivers (Hobbyking own brand).

Avoid the DSM2 types - won't work with your TX if it is new.

[J D 8]

Retro Radio is well in vogue today,with modelers resurrecting old radios having them converted to operate on the modern 2.4 system should you still want to keep your Kraft set going.

I still have my Futaba M series operational.

[Paul Marsh]

I have a couple of models with some very old Sanwa servos in them. I was going to change them, but they are powerful work perfectly and did check them before flying the model. They are not the 102 ones, but the early 80's ones. There were good servos and not so good. Sanwa always made good radios, nothing special, but it worked.