I define "external ballast" as this:

Looks like a bunch of M-400A2s with a AE 25 spot replacement?

I see the signals are still incandescent too. The closest set looks like Eagle Mark IVs.

Looks like it was taken somewhere in Utah, maybe SLC with the weird street numbers lol.

Also, I did restore this photo to color, However, It is not my image. These are Ge M400A's. Probably Mercury to HPS or just HPS. They where removed back in 2006 when UDOT added a median and teardrop fixtures

This is St. George, Blvd. I think in 1989.

Looks like a bunch of M-400A2s with a AE 25 spot replacement?

I see the signals are still incandescent too. The closest set looks like Eagle Mark IVs.

Looks like it was taken somewhere in Utah, maybe SLC with the weird street numbers lol.

lol. What fixtures do you see?
Found a date: 1991

What do you mean by external ballast?  Here's a spiral CFL with a non-integrated ballast, but they aren't common.

Mine (with external ballast) starts differently. How can it be electronic ballast? (I have video)

See here. 7H is August 1977/1997/2017 - you will have to decide the decade based on the lamp design, if you think thay're very new or very old lamps.

I have two 135W Philips sox lamps whith the code 7H on.
I can't find any date-information on the internet about them.

I thought this section could use as an advice After all, the suggestion is also part of an advice there