I just received my first ever Z scale locomotives. A Marklin GG1 and a MicroTrains F7. Does anyone operate these with the Z techk throttle? Micro Trains specifically states that pulse power should not be used due to excessive motor heating. The Z Techk definitely produces smooth slow starts on both locomotives but I’m concerned about running them for any extended period of time using that throttle. I have also found that the F7 is extremely loud and produces considerable gear noise and whine. It seems to be worse with the body shell in place. It’s actually far louder than the GG1 or any N Scale locomotive I own. I was just wondering if that was typical. Thanks, Bob
Same here, great runners and pullers but they do growl. I was able to quiet them down a little with some aero-lube grease in the trucks. The MTL GP35 is much quieter, I have a hard time going back to the F units now that I have a few of the geeps. Not familiar with the above mentioned throttle, sorry.
Bob, the Ztechk controller will not hurt your engines. I am not a electronic guy, but I ran my trains with it, and it didn't cause any problems. John
Hi Bob, Welcome to the Z Scale forum of Trainboard! Yes the F7 does sound like a coffee grinder, and they pull like a mule. I have ran a pair with an MRC 2400, and they did get real hot, but that's because the pulses coming out of the 2400 are 18 volts. I don't know how high the pulses on the Zthek throttle are, but Lajos is a Z Scaler, and he knows our voltage limits, so I am sure the pulses are low enough to be safe. I have also ran my F7's with the Gaugemaster electronic track cleaner, and that puts HF pulses of up to 350 volts as we measured with a scope, and the Gaugemaster has not damaged any of my locomotives, although I only used it for 1.5 years, having switched to DCC for all my Z Scale locos now.
The MTL Geeps are far much quieter, and in my opinion they have even far better low speed abilities than the MTL F7. I think it's normal as these locos have a 25-year difference in design. Myself I consider parting with my F-units, as furthermore I'm turned towards modern era. Dom
Well, Bob, the F-7's are loud for sure. I am not certain what it would take to decrease the level of sound, but they do run well. I use a Jorger with mine which I beleive is similar to the Zthek controller and have not had any problems.
Bob, The Pulse Power that MTL is talking about is the classic '70s power packs with 60 or 120Hz pulse power. It makes a difference whether the voltage ramps up (like sine waves) or turns on/off 'instantaneously' as a square wave or Pulse Width Modulation (PWM) does. The Joerger (and others) plus DCC all use high frequency PWM and will power the motor safely. As for the noise, the motor is the issue. Its not the most effecient design, more than 10+ years old and brush type motors are ineffecient, power wise. Mount it in that large mass and place it in a plastic shell and it's going to be noisy. But they'll pull anything you put behind them.
Thanks for all of the responses. They really made me curious as to just what the output waveform of the Zthek throttle looked like. To find out, I dusted off my oscilloscope and took a look. It is of course a pulse width modulated throttle but much to my surprise the pulse frequency is a very low 66 Hz. The pulses vary in width from a very narrow 20 microseconds at minimum throttle to pure DC at maximum. The leading edge of the pulses is extremely sharp while the trailing edge is more gradual. I can see why the F7 makes so much noise at low throttle settings using the Zthek. When using a non pulse throttle it’s quieter but as every one said not very quiet. The throttle doesn’t seem to affect the noise level of the Marklin GG1 which is very quiet. For those interested I’ve attached a sketch of the output waveform of the Zthek at a minimum and a 50% throttle setting. The input to the throttle was 10 VDC. I'll monitor the locomotives for a while to make sure there's no overheating problem.
I would think those pulses of 9 volts are low enough not to cause noticeable motor heating like the MRC 2400 power packs pulses does. Thanks for sharing the scope traces, the slow pulse decay is interesting.
You may want to look at Glenn Chenier's Wheel Wipers for better power pickup on the F7, otherwise, the above-mentioned info (and lubrication) is the best advice you'll find in Z Scale. Welcome Aboard! Michael
