you guys are awesome, that is fantastic info. Thanks so much! Going to be looking for such ballasts.

To be continued....

After studying the example images, I have one more question.

Since the 80 W MV lamp operates at 115 Volts and 0.8 A, what specs does the ballast need to have?
For example, lets say I find 2 X 40 Watt ballasts, do I need to make sure each ballast can provide (roughly) 55 Volts and 0.4 A to the lamp (each)?
Meaning, once they are connected in parallel, they would provide the right amount of current and Voltage to the lamp?

Would this ballast (2 of them) do the job?

http://www.howardlightingproducts.com/Documents/SpecSheets/Ballast/ElectronicFluorescent/E2-40RS-120MC.pdf

What i drawn here is supposed to work with magnetic ballasts only. dont do it with electronic - you'll most likely blow the ballasts

In parallel connection voltage remains same and current sums up. F40T12 is 103v 430mA so will sum up to 103v 860mA which is pretty close to what the 80w merc needs

oh yes right.

The one below seems to be a good fit:

http://www.amazon.com/Radionic-ES140HTP-Magnetic-Ballast-Fluorescent/dp/B00D3QIXB6/ref=sr_1_5?s=hi&ie=UTF8&qid=1374599221&sr=1-5&keywords=F40T12+magnetic

I just find it very confusing finding out what the output voltage is. I can't seem to find it for this one

On a working F40 the voltage is about 103v. For starting the 80w merc lamp needs less than 240v (since they start on line voltage with 240v), i did not find he OCV written anywhere but i dont expect problem with too low OCV failing to strike the lamp

Look at this one - it is perfect (2 of those)
http://www.radionic.net/D340TP_P2614.cfm

Though a bit more expensive

If you buy the D340TP Preheat ballast wiring is straightforward, just measure to make sure they are really in phase and nothing unexpected is going on



As for the ballast that you found, it have a downside in that it have 4 wires coming to te lamp. This makes the use of the ballast more complicated and requires more testing to be done because of one more possible issue present - shorting out the heating coils of the ballasts against each other. This is the same order of complexity like using 2 2-lamp ballasts, so if you have a few 2-lamp ballasts on hand you won't save much efforts by buying this, an can save the expense....

But i think it would be possile to test with those ballasts as well, worst that can happen is that the testing will show that the ballasts are not usable for running the merc lamp but youll be able to use them for other purposes...

If you buy the ballast you found in the 1st place, post a note before you go powering up the mercuy lamp so we can take the multimeter to find out more about the ballast's internals. And if you are buying this check out the price, they are listed for 13$ in Radionic's website might be cheaper to get from there depending on postage...

Thanks!! With regards to the D340TP, wouldn't the current be a bit too high?
The current shows 0.67 A. That, times two (after parallel connecting the 2 ballasts together) would make too much current for the 80 W MV right?

Thats the current pulled from the supply, not delivered to the lamp. F40 is supposed to get 430mA so thats what a proper 40w ballast outputs. Since this ballast have ballasting factor 0.85 for 40w the actuall current will be a bit less , so the 2 of them will underpower the lamp somewhat but not too bad

Awesome... I'm excited about this
I will be looking for 2 of those ballasts!!

Will update the post once I have them.. Thanks for all your help!

Ok here's an update on this. I haven't ordered the magnetic ballasts yet, because I was stil curious to see if I could get the bulb to work with the Sylvania  QTP 4x32T8/UNV ISN-SC ballast.

Here is how I wired it up:



There are a couple of things that I do not know about this ballast, for one, I do not know if I can sum up the channels to put the ballast in phase.

The result was that the bulb did light up without any problems:



I waited about 5 minutes and noticed that the bulb was not reaching its full brightness (the picture shows the bulb after 5 minutes). I didn't have a battery for my multi-meter so I was not able to record any Amps or such. I ended up connecting my kill-a-watt meter to my outlet, and connected the ballast + lamp setup to it. At least this way I was able to see how much the ballast is drawing to get an idea. Here are the numbers (after 5 minutes):

42 Watts
0.34 A

I am not sure what happened there.. Is it safe to say that this ballast is not suitable to run its channels in phase? Because if it would, the ballast would have been drawing more current and Wattage wouldn't it? Or did I wire things up the wrong way?

High frequency electronic ballast therefore unsuitable - this alone is sufficient reason

Depending on ballast construction blue/blue may or may not be same phase. i'd guess they are, but with 42w full power at the mains the 80w merc lamp is getting at most 40w (possibly the ballast detects it as some T5 lamp and drives it with lower current accordingly etc). 40w on 80w lamp is pretty bad underpowering and is likely to lead to significant blackening of the arc tube

Don't operate this lamp with HF. This would cause the lamp to catch acoustic reasonances, and if you would be managed to reach to 80W and full brightness with the HF ballast, the lamp may explode because of this.

thanks guys. I had the lamp running on this ballast for maybe 10 minutes tops (I had two runs of 5 minutes).

On to the next plan, getting 2 magnetic ballasts...!

Radionic doesn't ship to Canada... sigh.....

The search for a suitable ballast continues

Do you have any pair of matching magnetic ballasts ?