PA-20a Interceptor sirens

[Stampeed Valkyrie]

I know there are people on that enjoy the vintage like I do.
Just wrapping up a cleanup and function test on 2 PA-20a Interceptor sirens.
1 is a 2D and 1 is a 2E.

I know a few people following my posts already figured this out by now.

I also managed to snag a CP-25 siren for a song and a dance, recently at a flea market. Figured this would be the time to see if it does what it should.



video..

So the one question I have is what does the slide toggle switch on the main board do? I have some pics internally, I'll try to dig one up and post it here.

 

[shues]

I believe the slide toggle switch to which you are referring may be for the PA mic pre-amp:

Source: https://www.fedsig.com/resource-document/file/8018

 

[Maxim2Eng]

Nice snag! Personally, I prefer the lower pitch of the D *…great demo! Thanks!

Edit: *It’s the same vintage as me.

 

[Wailer]

The PA20A series 2D was introduced in 1969 and I've seen/heard emergency vehicles as late as the 1972 model year equipped with that version. The one you have sounds like it might need new capacitors, but the circuit is designed to produce deep slow rising wail and yelp tones.

The PA20A series 2E sounds like it is operating normally. It is designed to produce high-pitched wail and yelp tones like the electronic sirens that are in use today. The high pitched tones sound better with small speakers like the TS100. I think production of E series ended in the early 1980s. The E series is by far the most common version of the Director and Interceptor. Federal made tons of them.

 

[Night Patrolman]

The PA20A series 2D was introduced in 1969 and I've seen/heard emergency vehicles as late as the 1972 model year equipped with that version. The one you have sounds like it might need new capacitors, but the circuit is designed to produce deep slow rising wail and yelp tones.

The PA20A series 2E sounds like it is operating normally. It is designed to produce high-pitched wail and yelp tones like the electronic sirens that are in use today. The high pitched tones sound better with small speakers like the TS100. I think production of E series ended in the early 1980s. The E series is by far the most common version of the Director and Interceptor. Federal made tons of them.

And let's not forget the associated variants such as the PA70/PA100, PA150/PA200, PA170, or the combo light/siren control box the PA1000 "Siracom".

 

[Wailer]

And let's not forget the associated variants such as the PA70/PA100, PA150/PA200, PA170, or the combo light/siren control box the PA1000 "Siracom".

Yes, you are right. The following models have the same siren oscillator circuit and produce the same fast rising / slow falling high-pitched wail and yelp tones:

PA15A series 1E
PA20A series 2E
PA20A series B (c. 1980s)
PA70
PA100
PA150
PA170
PA200
PA1000

Of all of these models, the PA200 was the most successful design. I believe it was produced from about 1974 until 1989 and there were no changes to the circuitry over the course of production.

 

[Night Patrolman]

Yes, you are right. The following models have the same siren oscillator circuit and produce the same fast rising / slow falling high-pitched wail and yelp tones:

PA15A series 1E
PA20A series 2E
PA20A series B (c. 1980s)
PA70
PA100
PA150
PA170
PA200
PA1000

Of all of these models, the PA200 was the most successful design. I believe it was produced from about 1974 until 1989 and there were no changes to the circuitry over the course of production.

Fascinating. I also have another question about these sirens: are there any differences between the PA70/PA100 and the PA170? They look so similar.

 

[Wailer]

Fascinating. I also have another question about these sirens: are there any differences between the PA70/PA100 and the PA170? They look so similar.

The power amplifier box is different. The PA70/PA100 amp kind of looks like a transformer with a heat sink, while the PA170 amp looks like a partial PA200 chassis/cover.

 

[Night Patrolman]

The power amplifier box is different. The PA70/PA100 amp kind of looks like a transformer with a heat sink, while the PA170 amp looks like a partial PA200 chassis/cover.

OK, thanks for clearing that up!