Background:
The original Mini-Z has a 27Mhz AM radio. The problem with AM radio is that cars can get out of control if there are too many people running together. Some locations are naturally prone to glitches, which cause cars to get out of control. Usually, it always happens on the same part of the track. Sometimes, you learn to compensate by trying to speed thru that area as fast as possible, and stay in the middle of the lane so you don't crash. Then came AD band. It is basically FM. AD band runs on 25Mhz. AD band solves the problem with glitch, and various parameters can be programed too. However, AD band mysteriously turns itself off for no appearent reason. The latest theory on why that happens is because of static. Static spray seems to help some, but sometimes nothing helps. Therefore, AD band is not a perfect solution also. The latest radio is the ASF radio. The radio use 2.4Ghz frequency, and it selects the frequency for you when you start the car up. The radio works great as advertise. However, and there is always a however, to get into reverse, you have to hit reverse once, stay in neutral for half a second or so before hitting reverse again. That half a second may not seem too much, but it is eternity in a race when you are trying to get out of the way in a high speed corner so others don't hit you.
Upgraded Radios:
Why use a radio other than the stock? There are two reasons. One is more functions like exponential and end point adjustment. The second reason is response time. Radios like the Airtronics M8 has a response time of 12 ms while radio like the Futaba 3PK has response time of 8ms per the Spektrum website. 12 ms is just .012 of a second and does not sound like much. However, if you do the math, a mini-z top speed is about 12 mph. Modified can be faster. Let say a mini-z car travels at 10 mph. That is 14.6 feet traveled every second. In .012 second, the car would have traveled .176 feet or 2.1 inch. Imagine you see an obstacle up front, by the time you react to it, you would have to add another 2 inch of extra travel to the car. For a little car, 2 inch is a lot especially when you are trying to take a corner, and want to get as close to the apex as possible. Hence the advantage of a high quality radio.
If you are running AM band, any 27Mhz AM radio will run the mini-z AM board. i-Waiver radio will also run mini-z. Although the new i-Waiver that will come out soon do not have 27Mhz frequency, and will not run mini-z. X-mods crystals will fit mini-z radio and car, but the radio themselves are not compatible.
Top of the line radios:
KO PROPO radios are the standard for running mini-z. They are the native platform since KO makes the mini-z board in the car. All the parts and components fit together with no modification especially if you are using AD or ASF band. KO is also known to have bullet proof electronics. However, feature wise, Futaba and Airtronics have extra bells and whistle features that KO does not. How important those are depends...
KO PROPO EX10 Helios for mini-z. Can use a RF-501A AM module to run mini-z. The radio has 3 modes, normal, super HSR and Advance HSR. Super HSR is 33% faster than normal mode. Mini-Z AM board can run normal and super HSR signals. The advance HSR setting only works on AD and ASF band.
KO PROPO EX1-UR Due to popular demand, the old MARS-R is back. This is the original favorite radio used by many world champs. The electronics inside are all new though. The radio is faster than EX10 as fast as Esprit III Universe, but the quick steering cannot be used on mini-z. This is a good radio instead of EX10 if you have smaller hands, or if you like the old school EX1 radio.
KO PROPO Esprit III Universe This is the top of the line stick radio. Excellent ballanced and feels very natural in hand. Stick radio are popular in Europe, but not so much here in the States. It will take a little getting use to, but the advantage can be substantial. Stick allows you to to have more precise throttle action using the thumb instead of using the trigger. The older Vantage stick radio cannot be used for mini-z since it only operates on FM. For AM band, use RF-402A module. Note, the throttle preset does not work on this radio with ASF band. Throttle preset is important because it lets you get into reverse with press of a button. Makes that 1/2 second delay shorter.
Futaba 3PKS radio can be adapted to run mini-z ASF or AD band using the #500800
adapter made by PN. If you want to, you can also switch the wires in the mini-z
module to adapt to this radio instead of using the PN adapter part.
Reflex racing outlined the procedure. Futaba sells an module for mini-z
AM band. The 3PK radio is advertised to be even faster than the EX10 Helios.
According to some, the 3PKS some how puts out stray radio waves that interfere
with Ko Propo radio and to a lesser degree with Airtronics radio. When several
people are using 3PKS at once, glitching is for sure. Two extra feature the
3PK has that the KO radios do not have is more custom tailored exponential curves
and ABS break mixing with steering channel. The 3PK is the only radio out of
the 3 brand, KO, Futaba and Airtronics to have ABS mixing feature. What it does
is it will automatically turn on the ABS function when the steering wheel is
turned. That way, you can brake as hard as you want to in the straight, but
as soon as you turn the steering wheel, ABS kicks in to pulse and reduce the
braking to prevent spinout in the turns. May be a good feature if you are not
as coordinated with the brakes as the experts.
For the KO mini-z module to be used on Futaba, the connector is essentially
the same, only the pin out are different. Therefore, modify the wires leading
to the pin on the mini-z module. The heart of the operation is below: (Picture
from Reflex racing.)
Latest Futaba 4PK. This radio is incredibly expensive at close to $500. For mini-z, the main advantage is the added steering to brake mixing. It can be set up to automatically reduce braking as steering input is increased. Brake hard while going straight, but braking gets reduced as steering input is added. As with most of these "features", they get turned off after a while. They are not that helpful in mini-z IMHO. This radio use FASST transmission protocol. That is not sutable for mini-z, but some racers in Asia managed to crack the hardware to install an ASF board inside the radio. See mini-z forum. There is actually enough room inside to install the circuit board from the RF-901SM ASF module. See also a Russian forum link. If done properly, you can still use the Futaba FASST for other vehicles. Is this worth $500? Probably not since Ko-Propo does a good job controlling the mini-z. However, is a cool radio just because is the latest and greatest.
Need to connect a jumper from 4PK to the circuit board removed from the ASF transmitter module.
More details of which wire goes where on the ASF board.
These are the connections:
Futaba 4 PK -------->ASF Module
1 --------------------> 1
2 --------------------> 2
3 Not Connected
4 --------------------> 3
5 --------------------> 5
Need an extension for the binding switch on the ASF board and the indicator light.
Airtronics M11 - Airtronics sells an AM band mini-z module for this radio. The module is part number# TM-151CW. The module is for the loder M8 radio, but should work for the M11 radio as well. M8 and M11 modules are interchangable per the www.spektrumrc.com web site. For AD band or ASF, you will need the PN adapter part. You can also switch wires in the AD or ASF module. Here is the pin out diagram to do it. Hint: 10.88V and 10.95V is the same as the V+ pin. The M11 radio has an extra feature that KO does not have, which is to allow you to custom tailor the steering exponential curves.
Older Radios
Don't ignore the older EX-I MARS R radio. You can sometimes find them on ebay. It has pretty much all of the features as the more expensive EX-10, Universe or the EX-I UR. The only thing that it does not have is the quick steering of the UR, which does not work on mini-z anyway. Get the MARS R instead of the regular EX-I. It Super HSR circuitry for 33% faster response than the EX-1. The MR020 and MR015 receiver is designed to operate on both HSR and non HSR radios. These radios can also readily run AD or ASF band like the more expensive EX-10 Helios. For AM band, per KO tech department, you can use the same module as the Helios, but KO does make a module, RF-103A, No. 15782, specially for the Mars. Dinball from Hong Kong sells it.
Economical Radio
Futaba 2PL is a popular radio that has a precise feel to it. Suppose to have good electronics too. The 27Mhz AM model will run mini-z with no modification. From the mini-z racer forum, the 2PL is suppose to have faster response time than the MX-A
Airtronics MX-A in 27Mhz AM is another good economical radio, but not as popular as the 2PL. This has variable steering exponential while the Futabe 2PL has ABS braking. Variable steering exponential is where you can adjust how much exponential to have in the steering. That is the trade off between these two radios.