# Running two F7 A Unit desiels with a B unit inbetween



## rjbord (Feb 13, 2012)

I want to run two F7 A Units with a B unit in between. Any issues?; Was this configuration ever used?; These are LGB engines.


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## Trains (Jan 2, 2008)

I run my LGB F units A-B-A all the time, with no problems. Run all three off a battery car.
I seen them run A-B-A, A-A, A-B-B-A, A-B-B-B, A-B.

Don


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## Gary Armitstead (Jan 2, 2008)

Posted By rjbord on 01 Mar 2012 06:31 PM 
I want to run two F7 A Units with a B unit in between. Any issues?; Was this configuration ever used?; These are LGB engines. 
I have an LGB War Bonnet setup ABBA. It has been probably 15 years since I last ran them, but I believe there is a way to set the switches on one of the A units to make your ABA set up work. I believe the one A unit just has to be isolated from the AB units. Maybe some can chime in here to give the precise answer.


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## Jerry McColgan (Feb 8, 2008)

The LGB F7's are among my favorite locomotives. The railroads ran them in many combinations and ABA was not at all uncommon.

The F7B actually has a double amplifier which will power the factory provided speakers in different combinations. You can choose to have sound from both an F7A and an F7B or from both F7A's.

In one ABA case I have the LGB sound system working an F7A and a trailing F7B plus a Phoenix sound system in the trailing F7A (I think it is a '97 Phoenix F7 sound system) so all three have sound. I find the Phoenix to sound the same (to my ears) as the LGB sound systems.

How about an F7-ABBBBBBA with sound blasting from all 8 locomotives?

F7 Interurban


From the F7B instructions:


*"F7B Operating Modes*


*This model is equipped with one speaker and two amplifiers. To control the amplifiers, this model (F7B) has a three-way sound control switch on the rear wall (Fig. 2): *

*Position 0: Sound off.*


*Position 1: The speakers in the front and rear A-units are on. This position is for an A-B-A combination. The speaker in the B-unit is off.*


*Position 2: The speakers in the front A-unit and the B unit are on. This position is for an A-B combination."* 
F7A Instructions

F7B Instructions


The critical switch is on the F7B. Also you should have a two wire harness to connect power to the three locomotives as the B unit has no track contacts. You also need the 4 wire harness between the B unit and whichever A unit you wish to have sound coming from. You do not need the 4 wire harness connecting the B unit to the other A unit unless you want sound from both A units.

Jerry


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## Scottychaos (Jan 2, 2008)

A 
AA 
AAA 
AAAA 
AAAAA 
AB 
ABB 
ABBB 
ABBBB 
ABBBBB 
ABA 
ABBA 
ABBBA 
ABBBBA 
ABBBBBA 
ABAAB 
ABBAA 
AABAB 
AAAB 
ABABA 

I could go on, but I think you get the point!  
any one of those combinations could have been found at some point, on some railroad.. 
Probably the single most common arrangements were: 
AA 
AB 
ABA 
ABBA 

Scot


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## Scottychaos (Jan 2, 2008)

Here is an unusual one, ABBBBA,
these were F-units in regular freight service, but the amazing this is..it was in 1999!



Having an A-unit at both ends (with their cabs facing in opposite directions) was the most common arrangement, so that the set could be run in either direction
without having to turn any locos or break up the set..*usually* B-units would be found in the middle,
but not awlays:

F-unit mixed lashup photo 1

Any combination of A and B units is plausable..
usually (99.9% of the time) with the cab of an A unit in the lead..
although there are even known exceptions to that!
The Wellsville, Addision and Galeton RR (WAG) was known, in the 70's, for occasionally using a single F7A
on short trains..they couldnt turn the unit for the return trip, so the unit hauled the train backwards..
the single A unit pulling the train, at the front of the train, but with the locomotive running backwards..
a crew member had to stand in the rear door of the unit, which was leading, to watch the tracks ahead as the
train went along..

F units, A or B, could also be mixed with non-F units..
here is a EMD AB set, with an Alco FB, and an Alco Century road switcher:
F-unit mixed lashup photo 2

Scot


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## Bill Swindell (Jan 2, 2008)

I think I read somewhere that direct wired MU consists are limited to 6 engines. Using R/C extends this.


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## Dan Pierce (Jan 2, 2008)

NEVER, NEVER tie 2 F7B units with the 4 wire cabe!!!!!!!! This will tie the audio outputs to each other and possibly destroy the sound boards!!!!! 

The 4 wire cable is only for connecting a B unit to an A unit. 

The 2 wire cable is a power cable and is used to tie all F7's together.


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## Jerry McColgan (Feb 8, 2008)

Posted By Gary Armitstead on 01 Mar 2012 08:05 PM 
Posted By rjbord on 01 Mar 2012 06:31 PM 
I want to run two F7 A Units with a B unit in between. Any issues?; Was this configuration ever used?; These are LGB engines. 
I believe the one A unit just has to be isolated from the AB units. 

I seem to recall that there was some sort of complication in hooking up an ABA or an ABBA. Its been a long time since I did it and I don't remember if it was under track power or if decoders were installed.

Perhaps I am mistaken - it was a long time ago and my memory is not very good anymore.

Jerry


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## Gary Armitstead (Jan 2, 2008)

Posted By Jerry McColgan on 02 Mar 2012 01:53 PM 
Posted By Gary Armitstead on 01 Mar 2012 08:05 PM 
Posted By rjbord on 01 Mar 2012 06:31 PM 
I want to run two F7 A Units with a B unit in between. Any issues?; Was this configuration ever used?; These are LGB engines. 
I believe the one A unit just has to be isolated from the AB units. 

I seem to recall that there was some sort of complication in hooking up an ABA or an ABBA. Its been a long time since I did it and I don't remember if it was under track power or if decoders were installed.

Perhaps I am mistaken - it was a long time ago and my memory is not very good anymore.

Jerry

Jerry,

Like I said, it's been a long time since I ran these. In the ABBA mode I believe I ran of of the power cables to run the "front" AB and then connected the "rear" AB with a separate power cable. On the ABA, I believe I connect the power cable between the 'front" AB and just let the trailing A unit run on it's own. Memory is foggy on this. But it was run on trackpower. Way before I got into battery ONLY!


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## stevedenver (Jan 6, 2008)

1 i think the a-b-a lash up for LGB is optiimum as between sound and starting voltage-everything seems to be better sound coordinated-ie full stop throttle up etc 
2 if you run an a-b-b-a -what you must do is simply run two A-bs back to back-not connected-and the sound set for this config 
3 i love a-b-b-a and bought mine for this reason HOWEVER 
i only run mine as a-b-a as the sound from two a-b lash ups, back to back is out of phase, ever so slightly-i find it annoying 
you might not 
-basically what you have is the two sound units, acting separately, almost but not identically, there being say a milisecond or so gap , not even an echo, not a pulse-just not quite right-and not like the 'real thing' imho 
ymmv


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## Jerry McColgan (Feb 8, 2008)

Another factor with track power and a ABA or ABBA configuration is that the track magnets activate the bell and horn. 

With an ABA it is easy enough to position the B unit so the bell and horn are right and in an ABBA the track magnet reed switches can be disconnected from the 2nd B unit sound board but (if I recall correctly) it can get a bit complicated if you want both (or all) sound units to sound the bell and horn. 

As for the sound delay (I'm just guessing here) this might have to do with the 2nd B unit facing a different direction (putting it out of phase from the 1st AB unit?) or it might possibly be corrected by reversing the polarity of the speakers in the 2nd AB units. 

No facts - just guessing.

Unfortunately there has never been much if any published technical data on LGB sound systems or other electrical circuits. Perhaps Klaus Stork, Dan Pierce/Train-Li, Walthers or someone else like Watts might have such information.

Jerry


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## rjbord (Feb 13, 2012)

Thanks for all the good advice -I know what to do now!


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## Dan Pierce (Jan 2, 2008)

To rid a second F7B of bell/whistle sounds, just place a switch on the middle lead of the reed sensors. 

All LGB engines use a common middle line to the 2 reed sensors. 

And a better way is to use a DPDT center off switch and cross wire it to the 2 outer leads and then you can reverse the bell and whistle sensors as well as turn them off.


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