# Size Does Matter



## Paul Norton (Jan 8, 2008)

A few months ago Doug Matheson (AKA Dougald) offered to buy my custom painted CNR RS-3. 










As the 75 MHz receiver in this diesel has been plagued with radio range problems, I offered to install a Super Socket with radio noise suppression components (four large chokes) and a Black Kat antenna. The conversion also included a lithium-ion battery pack and LED lights. 



















Yesterday we tested the locomotive with Doug’s new 75 MHz transmitter that was equipped with a rubber ducky antenna. Having had great success with the installations of Super Sockets in my FA-1 and NW-2, I was greatly disappointed when we encountered radio range problems beyond 15 feet. 

I removed the Ruby Ducky antenna and added three feet of 22 gauge wire in its place. The radio range jumped to 75 feet. 

Today I installed a telescoping antenna on the transmitter and gave the locomotive to Doug to test. He reported back that he had reliable and responsive radio control at 135 feet, the length of his garden railway. So when it comes to transmitter antennas, size does matter. 

A new article on how to convert an Aristo-Craft RS-3 to on-board, battery power and radio control has been added to the Battery Power Section of our club web site. To view the article, click on the following link. 
Battery Powered RS-3


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## Tom Lapointe (Jan 2, 2008)

Paul, proper radio antenna length *(especially on a transmitter!)* is dependent on the frequency in use; most RC transmitters use 1/4 wavelength antennas (wavelength is inversely proportional to frequency). Improper antenna length on a transmitter can, in some cases, *cause damage to the transmitter's final RF output transistor*/DesktopModules/NTForums/themes/mls/emoticons/shocked.gif (Although this occurs mainly at transmitter power levels higher than most RC transmitters). Receivers aren't quite as critical (there's no damage issue); just the receiving range would be shorter. Most antennas for RC use are 1/4 of a wavelength long. 
Dividing 234 by the frequency in MHz. will give you the length for 1/4 wave antenna in feet, just multiply that by 12 to get it in inches. For 75 MHz., 234 / 75 = 3.12 feet, or 37.44 inches. This would be the proper length for a 1/4 wave wire or telescoping rod antenna. It IS possible to make an antenna physically shorter (but ELECTRICALLY the proper length) by adding inductance (a coil) in series with it; "rubber ducky" antennas take this practice to an extreme length by making the *entire antenna* in coil form (usually a spring which is then encased in rubber). 
This is something I've had *LOTS* of experience on in years past /DesktopModules/NTForums/themes/mls/emoticons/blush.gif - 39 years as a ham radio operator, & 15 years working in the two-way radio field. (But no longer - the computer industry pays *much better!).*/DesktopModules/NTForums/themes/mls/emoticons/w00t.gif Tom


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## Dougald (Jan 2, 2008)

I have been an interested bystander through several years of frustration of many of the OVGRS members with the Aristo 75 MHz gear. In fact, many of us also use RCS because it has proven to be more reliable and more ergonomic though higher priced. 

But it is possible that the Aristo stuff has been unfairly maligned though as Paul has shown, it is very sensitive to the installation. Over the past 2 years, Paul has had some great successes with the 75 MHz gear. He has successfully built his own socket board including noise suppression, experimented with the antenna mount in locos to get better reception and shown how important a proper antenna is at the Tx. 

The latest episode proves yet again that even if the coiled wire in the stock rubber ducky antenna on the transmitter is the correct calculated length, in the real world it did not work. But a length of wire randomly cut so that it would not drag on the ground gave excellent results. The telescoping antenna (from Radio Shack) gives even better results when fully extended and much better than rubber ducky performance at all lengths. 

While we all wait for advances in R/C technology, the Aristo 75MHz line is reasonably inexpensive and deserves some consideration in those projects where the loco should not cost less than the cost of the R/C gear. In fact, given that so many folks have had problems with their Aristo 75 MHz gear, it can often be bought second hand very cheaply. With some care. Paul has shown that very acceptable results can be achieved. 

The yardmaster at Craig Leigh now has a new switcher for those diesel ops on the IPP&W this season. The very nice CN green and gold paint will help even the balance with the grey and maroon CPR brigade. 

Regards ... Doug


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## Paul Norton (Jan 8, 2008)

The telescoping antenna that Aristo-Craft provides, to replace the Rubber Ducky on either their 27 MHz or 75 MHz receivers, is 30 inches in length. Although it may not be the exact tuned length required, it does increase radio reception dramatically. 

If used in a trailing power car, neither the 75 MHz or 27 MHz receiver require radio noise suppression components as they are isolated from the radio noise generated by the motor(s). I recently sold a 4-6-0 steam locomotive with the 75 MHz receiver mounted in the tender. 










Although there were no radio noise suppression components added, this locomotive got more than 100 feet of reliable radio range using the 75 MHz receiver with a Black Kat antenna, and a telescoping antenna on the transmitter. 

I was able to triple the range of the 27 MHz receiver in my Evans power car by replacing the wire antenna with an M-27-Lite micro antenna from 
E-Cubed R/C and using the Aristo-Craft telescoping antenna. 










With this short antenna on the receiver and a telescoping antenna on the transmitter I was able to obtain reliable and immediate radio response at 135 feet, the length of Doug’s garden railway. 

I have obtained the same results with a 75 MHz receiver mounted in a Super Socket in an FA-1, NW-2 and RS-3 diesel. In all cases the wire antenna on the receiver was replaced with a Black Kat antenna, and the Rubber Ducky was replaced with a telescoping antenna. 










My experience has also revealed that dollar store AA cells in the transmitter will quickly run down and reduce radio range. Aristo-Craft recommend Duracells. They cost more but last longer and provide maximum radio range. 

If you feel that building your own Super Socket is beyond your soldering skills, noise suppression boards are available from RCS Agents.


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## Stan Cedarleaf (Jan 2, 2008)

Wonderful, Paul and Doug. I'd just like to confirm your findings. I've been running the Aristo 75 Mhz onboards with 50-60 foot range for over year. I can reach most everywhere on the layout. Telescoping antenna on the TX and an the OEM antenna wrapped around inside the car or trolley. 

I've been quite pleased with them. Even put the 75 Mhz HO receiver in a trolley bash. Range on that is not as great as the G Gauge but it works quite well.


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