Spectra Internal PA?

[bellersley]

I've been trying to get the Internal PA function of a Spectra to work.

I've enabled the option and programmed a button as PA. However, when I key up in PA mode, I hear a slight hiss from the speaker, but no actual audio.

Any idea what I'm doing wrong?

[Mike B]

I was told the internal PA function is part of the Metrocom version of the Spectra. So, it requires a special Metrocom option board.

[Jim202]

Are you sure that you don't need the external siren package to do what your trying. Normally for a PA option, your looking to have an amplified sound from the radio or the mic to come out of a speaker mounted outside the passenger compartment of the car.

You need an audio amp to drive the speaker with say 25 to 100 watts for a Public Address use. There is no high power audio amp in the Spectra. Only the small internal audio amp to drive the normal car speaker at a couple of watts.

Jim



[quote="bellersley"]I've been trying to get the Internal PA function of a Spectra to work.

I've enabled the option and programmed a button as PA. However, when I key up in PA mode, I hear a slight hiss from the speaker, but no actual audio.

Any idea what I'm doing wrong?[/quote]

[Cowthief]

Hello.

There is an option for an internal PA.
This is used in things like school buses, and as such correctly called internal PA.
I see nothing special about this unit.
There is also a spectra with a small external amp unit that drives trumpet speakers, but that is along the lines of the siren unit.
The railroad spectra can be fitted with both internal and external PA.

[kc7gr]

If you're serious about getting external PA capability, you absolutely, positively, have to get an HLN1185 series external siren/PA amp. The Spectra's internal chip just doesn't have the power to drive a proper external speaker (and, when I say 'proper,' I'm NOT referring to the Taiwanese trash found at Radio Shack -- I'm talking real siren/PA speakers, hundred-watt capable driver, such as the Whelen SA214).

The 1185, and (often) its associated cables, may be found on Greed-bay, or at ham swap meets.

Keep the peace(es).

[bellersley]

Well, it's not a feature I'd likely use, I just was curious as to how you would use it, I played around with it but couldn't get it to work. That's likely as far as I'd go with it.

[Cowthief]

Hello.

The feature is good for school bus use,' alright everybody we are here, off the bus'.
If the audio path it not selected, you will get the white noise from the amp and nothing more.
The ones I have seen have this odd rocker switch on the mic, one way is the PA and the other is PTT.
The RR spectra equipped with only the panel mount PTT, of course, does not have this.
The only RR spectras that will have this are in passenger car service, something like the budd cars in Ill.