KCat servo extensions
 

Unlike many of you knuckle heads out there, I have to disassemble my Kingcat for transport. So, what's the big deal right? well...today I barely averted disaster when post landing I discovered a lousy connection between my 36" lead from my rx and my booms. This connection allowed an intermittent signal to reach one of my stab servos. The result was a mild porpoising action of the airplane. fairly spooky because on deck it shows no signs of going south when you do a wipe out of the controls.

I'm using Cermark connections and one thing I've discovered on both of the 36" extensions I've replaced is that the sheath that covers the pins is shorter than the standard JR connections. This lead me to believe that perhaps they were defective but upon further inspection I've discovered that there's an optical illusion with the sheath they use. I confirmed the solid connection by using one of those yellow parson's connector.

so, ultimately what I want to convey is ensure you get a solid "snap in" connection when you press those leads together. I didn't pay close enough attention to mine and narrowly averted disaster.

I know there are a number of ways to secure our leads "heat shrink", "tape", "mini zip ties" whatever but however method you use if you take them apart for any reason just don't assume because they press together that you have a solid signal.

do a control wipe out prior to taxing out of the pits, hold short etc. you just might discover a problem. I did.

take care

Buck

RE: KCat servo extensions
 

In addition.. just a reminder to be careful with your choice of connectors in-line. We (at JR/Horizon) have seen some pretty severe resistance jumps/voltage drops from some of the 'discount' connectors on the market. They are NOT all created equal. When you start stacking multiple connections in-line between receiver and servo you can see as much as a 2v drop at the servo, making that nice 200oz" servo put out far less torque than rated.

I guess the short version of this is "Your radio setup is not the place to save $$$". It could wind up costing you a lot more in the end.

RE: KCat servo extensions
 

Buy your extensions from ElectroDynamics. Probably as cheap as Cermark and better.

RE: KCat servo extensions
 

mucho thanks amigos. I've learned my lesson and luckily it hasn't been at the expense of one of my airplanes.

keep on keepin' on

buck

RE: KCat servo extensions
 

Hi Buck:

I'm not sure you knew that I almost lost my Bandit at Tucson on Friday....I had a cheapo 3" extension between the switch and the RX and it went south as I was in the flare....Vinnie was spotting and said "Man that was a carrier landing"...I told him I only intermittently had it down final and in the flare.....


I don't know how that cheapo got into my Bandit.....must have been the only 3" extension I had handy.....

I use nothing but JR heavy duty or Andy Lo's cables and switches from ElectroDynamics/Cermark, and SR Nicads with the 18 ga leads.....and Duralites......

Over the past 4 years, I lost a HotSpot and Bandit to electrical frig-ups......doing my best now to avoid another disaster.....

Tom

RE: KCat servo extensions
 

Got a site link for these ElectroDynamics folks?? I have never heard of them


thanks,Steve

RE: KCat servo extensions
 

Tom

I didn't know about the near loss with the Bandit. Much like mine I guess, intermittent signal. we were able to get the servo to react on deck much like it had in flight. twitching up and down, which would translate into a mile porpoising motion. that's two connectors that went bad. what are the odds?

saving near 6 bucks an extension on a project the size of the King = a sizeable chunk of change but in the end game is it really worth it? I'm going to take a different approach for the next project.

I'm sure it's not typical and perhaps is just an isolated event. however, I just wanted to pass and "airframe directive" if you will to raise and "awareness".

sooooo, how's the Eagle coming?

what a great flying airplane

take care

buck

RE: KCat servo extensions
 

I think this is why BVM states in the Kingcat manual that you should use only JR heavy duty gold plated leads with your JR radio gear.

Over the years I have found that many of the off brand "after market connectors" do not make a good connection to the JR leads. I use Hitec servos and receivers for prop planes and in this case I do use Hitec servo leads. I think it is a good idea to stay with whichever brand you are using for all connections.

This is common sense I guess if you think about the fact that the pins in the connectors are not the same type of connector pins, same manufacturer, etc. In the past, I have disassembled two different brands of male plugs and measured the pins with a micrometer and there can be a substantial difference in pin size which will probably not make good connections to JR equipment.

It was very expensive for me to buy all JR brand leads for my Kingcat but I think it does eliminate any potential problems in this area and it is not nearly as expensive as buying a new Kingcat. Gary

RE: KCat servo extensions
 

From the research that I have found, a twisted lead or ribbon cable that is shielded provide the best RF rejection for our R/C systems. I find it odd that they are not readily available. I found a guy in Canada (Simon Van Leeuwen) that manufactures high quality twisted lead cables. The heavy duty connectors are rated for 4 amps each. The servo end of the extension has a provision for a locking clip that crimps to the servo connector keeping them securely connected until you want to take them apart. If you would like to contact Simon to find out more about these cables yourself then here is his info:

Simon Van Leeuwen
903, 617 - 15th Ave. SW
Calgary, Alberta,
CANADA T2R-0R4
(403) 244-5816 home

Here is his last email to me:
Hi Mike,

Good, any problems do not hesitate to ask. I realized reading RCU that I
probably did not mention the unique connectors utilized where the servos
plug in.

Yes indeed there are mating connectors that are locking! Folks who are
installing my harnesses in high vibration circumstances, or just want
the security of a positively locked connection can order the mating
connectors. The system can also handle significantly more current (when
both ends and their associated high performance pins/spring contacts are
employed), as much a 4A continuous. Generally they send me the servos
etc so I can properly crimp the mating spring contact on. However, those
with the know-how can do their own.

Again...any questions do not hesitate.

simon

RE: KCat servo extensions
 

I purchased a never flown jet that I'm redoing, how can I tell if these are high quality extensions ?..... They appear to be all JR, but I'm not sure of the gauge or quality.
Hey Tom on another thread you mentioned being interested in this opticle amplifier box. I'f I can get my plane to operate with out it by replacing it with snap on filters I'll PM you to see if ya still want it.
& Doug if you read this maybe you can tell me if filters can replace this box.
Jay

RE: KCat servo extensions
 

Andy's site is http://www.electrodynam.com

T

RE: KCat servo extensions
 

Ummm.... they are the one and the same extensions. BTW I used to use those extensions but had a couple fail and had a few of the ends get to where they slipped apart. I only use JR extensions in my Jets now.

RE: KCat servo extensions
 

Absolutely right Gary and a lesson hard learnt for me! last October I lost my Roo when a disimmilar plugs and socket pair failed. I used a high quality JR extesion lead with Multiplex servos. The fit is very tight and unbeknown to me the signal lead had pushed out on installation. All that held the pins together was the heat shrink I put over the connector pair. However after 20+ flights it finally parted whilst at high speed. The subsequent loss of control was quite violent and the model was an almost total loss. Just one or two servo left.
After investigating this problem I have learned that this is quite a common problem with dissimilar makes of connector so the advice must be stick to the same brand of extensions as your servos.

RE: KCat servo extensions
 

Most of the servo extension made from either from Taiwan or China.
I have no comment which brand is better. There all might came from same factory.
I had use all the brand name you guys mention. I found them all the same. You guys know how many jets I built a month. I how many servo extension I go thru.
I saw those servo extension was made from one of the factory I visit. I won't tell whom they made for.
So you guys tell me one brand is better than the other. I totaly not agree.
Check all your extension when do the install is best method. Don't believe this brand is better than the other.
Brg,
Tam

RE: KCat servo extensions
 

Hi Tam, yes you are quite right. Checking is the best way every time. Having previuosly used Multiplex plugs which are moulded and absosutely bullet proof, I had no idea that these uni plugs could coma apart in this way. Like I said lesson learned!
However, I disagree that they are all the same. I have bought all the different brands currently available in the UK and there is a differences in the way in which these things fit together. It's a small difference I grant you but enough to cause a crash if you are not aware of the danger.

RE: KCat servo extensions
 

If you look at the female plugs from different brands you will see that where they are crimped to the wire there is a difference in the way the crimp is made. I would think that if they are all the same and come from the same factory that the crimp would be identical but they are not so I think I would disagree also that the connectors are all the same. If you disassemble the plugs you can see the difference in how the pins are made as well. The physical appearance is different.

And there is no doubt at all that some do not all fit together properly to JR plugs. I currently have several different brands and some pull apart from JR connectors very easily but when two JR plugs are pushed together you can feel a positive locking of the plugs and they are much more difficult to separate.

The other thing to keep in mind is that just because mis-matched plugs feel tight when pushing the connectors together really does not mean anything. Some of them are tight because the plastic housings do not fit properly to JR connectors and it has nothing to do with how well the pins fit together which is what is important. Therefore going by feel really means little as far as how well the connectors will work.

I think there has already been a comment about the high resistance that can be created by improperly fitting plugs which will likely result in reduced power to the servo from the improperly fitting connectors.

In my original post I had mentioned that BVM recommends using only JR connectors with JR radio equipment. After having quite a few of the BVM kits I know that their equipment recommendations are based on past experience and extensive testing and I have learned to trust what they say and recommend. Based on this I believe that there are good reasons why BVM has recommended using only the JR leads for JR equipment...Gary

RE: KCat servo extensions
 

Gary,
I agree if the connector is miss match and get poor contact.
But I'm talking about the servo extension are made to fit exact connector to the servo brand.
At my shop. We had built many jets and install thoundsand of servo extension. We only use 22g and gold plated connector.
We had no problem with poor contact if install correctly.
From my experience. I find some of the use servo extension had poor contact. I guess it been plug-in and unplug so many time the pin got expanded. This apply to any brand.
I do run to some bad servo extension from the brand I use. But it is very easy to detected if pay attention to the wire. When you push the connector in.
If one of the wire are pushing out. That mean it connector pin is bad. That when you get the poor contact.

Like I said. Check your installation carefully. Any good servo extension do had bad one. This doesn't mean because of the brand name you choose won't get bad one.
Remember. All the servo extension was made oversea. There are made in mass quanity. No manufactor go to check one by one.
I saw how is made from one of the factory I visit.

My own opinion. I always shop for best products and right price for my customer.
Tam