# MRC Tech 7



## 4x4Tyrant (Dec 7, 2012)

Just wanted to know if the MRC Tech 7 series transformers have enuff amps to run a one loco train? I'm trying to find something not to expensive maybe 100 dollars and under, Thanks for the help and pardon my newbness. Thanks.


----------



## chuck n (Jan 2, 2008)

It depends upon the engine and how many amps it draws. The literature on this power supply says that it is rated at 20VA. That is Volts*Amps. At 20 volts the output would be about 1 amp, or at 10v (barely enough to move an engine) the output would be about 2 amps.

Most "G" gauge engines draw between 0.5 and 1 amp per motor. Sound, smoke generator, and lighted cars all add to the power drawn from the power supply. If you have steep grades (>2%) or tight curves (<5' diameter), that will also require the engine to work harder, hence draw more power.

Here is a link to the MRC site for this PS.

http://www.modelrectifier.com/train-controls/dc-power-tech4.asp

In my opinion it would be minimal. Probably OK for a short train under a Christmas tree. If your RR empire expands in the future you will need a more powerful PS and you would have to buy a new more powerful unit. I'd suggest a minimum of 3 amps, but higher would be better (10amps). 
Chuck


----------



## chuck n (Jan 2, 2008)

It depends upon the engine and how many amps it draws. The MRC site mentions, HO, N, and Z. "G" isn't specifically mentioned. The literature on this power supply says that it is rated at 20VA. That is Volts*Amps. At 20 volts the output would be about 1 amp, or at 10v (barely enough to move many of our engines) the output would be about 2 amps.

Most "G" gauge engines draw between 0.5 and 1 amp per motor. Sound, smoke generator, and lighted cars all add to the power drawn from the power supply. If you have steep grades (>2%) or tight curves (<5' diameter), that will also require the engine to work harder, hence draw more power.

Here is a link to the MRC site for this PS.

http://www.modelrectifier.com/train-controls/dc-power-tech4.asp

In my opinion it would be minimal. Probably OK for a short train under a Christmas tree. If your RR empire expands in the future you will need a more powerful PS and you would have to buy a new more powerful unit. I'd suggest a minimum of 3 amps, but higher would be better (10amps). I have a passenger train that draws about 7 amps, A-B diesel engines (2 motors each, 4amps) 6 streamliners with lights (0.5amps each, 3amps).

Chuck


----------



## Greg Elmassian (Jan 3, 2008)

Please remember that 20va does not guarantee that volts times amps = 20 at ALL combinations of volts and amps.

I learned that lesson on "rating" with my first MRC transformer, that stated it was 60va and could also get to 24 volts... well, at 24 volts it was under 2 amps.

It's a misleading rating system, kind of like "peak watts" on a stereo system.

I'd say it would not be good for G scale use at all. Look at the max voltage, only one of the 3 goes over 14.5 volts. One LGB loco running SLOW is about it.

Greg


----------



## 4x4Tyrant (Dec 7, 2012)

Thanks for the info guys, now what would be in your experienced opinions the best transformer to get that wouldn't be to expensive? Just something 3 amp then. Thanks for the time.


----------



## chuck n (Jan 2, 2008)

I found a 3amp Bridgewerks at an used equipment sale that was part of a tour of open houses in Phoenix a few years ago. I paid $100.

Check eBay and local meets. You might get lucky too.

Chuck


----------



## stevedenver (Jan 6, 2008)

I agree bridgewerks, 
these are the best, and have dedicated AC and fixed DC outputs, cooling fans and simple excellent customer support post sale as well.



or

LGB 6 amp power source using the LGB throttle-

let me suggest, as a guy that started with a couple of Stainz, and an old MRC 6200 (64 volt amps) 

you will likely soon outgrow a small power unit.
a small unit will be taxed by :
slow trains with longer loads 
trains on a grade
extended running with any load
and as mentioned, lights, smoke, accessories etc

I understand the shock of athe price of a better power unit, but if you're in it for the long haul, consider this. You WILL grow into a bigger unit in no time.

I can remember my small units slowly overheating until the circuit breaker came on , and then a wait for it to cool, ....repeat.


----------



## chuck n (Jan 2, 2008)

All is not lost if you out grow a small power supply. I use mine on my work bench when testing and checking out problems with my locomotives.

I haven't found a engine that I can't run with it for the short time needed to check something out.

Chuck


----------



## Mike Toney (Feb 25, 2009)

Does MRC still offer the Powermaster G throttle? It was supposed to be a decent throttle from what I heard. Local G only shop has one that powers thier layout when they use Analog mode. Mike


----------



## stevedenver (Jan 6, 2008)

the simple fact is, unless you find a nice used bargain, you are likely going to need to spend closer to 200-300 +for a decent power unit.

chuck is right, though, the smaller units find a place on the bench, or lighting or controlling accessories etc, and wont go to waste. 

the MRC g power is rated at 10 amps, imho, a 'lower end' of the upper ranks, but very good number of amps. 

I often run 3 locos, some double motors, and switches and a couple dozen incan building lights, semaphores with no problem off a bridgewerks 10 amp.

I can also vouch for the LGB 6 amp unit (AC) and its *later version* 'switchmans hut' throttle which 'converts' the AC to DC. It is a fine smooth powerful unit, but the problem is it says LGB (ie $$$). OTOH< I have since seen these at train expos and other sales for right around your price range, usually abandoned in some cardboard box with other odds and ends. 

don't you want to also be a 'G scale Tyrant'? LOL


----------



## Greg Elmassian (Jan 3, 2008)

There is a new power G on ebay, with buy it now of $150, new in box.

http://www.ebay.com/itm/MRC-Power-G...006053?pt=Model_RR_Trains&hash=item20f1e0f7e5

I'd buy it, they are a bit hard to find.

Greg


----------

