Mike58
New User
Posts: 2
Joined: Fri Jul 28, 2017 4:11 am

Unitrol 800 series siren power output transistor question

Fri Jul 28, 2017 5:42 am

Hello to the group. I'm hoping someone can help. I have an old Unitrol 800 series siren that has 2 blown SP3099 power output transistors. They are a TO-3 style matched pair and located on the bottom of the unit. Does anyone know of equivalent replacements for these transistors? I can't seem to find them listed anywhere. Also, is there a manual available for this unit anywhere? Any help is appreciated. Many thanks. -Mike

Mike58
New User
Posts: 2
Joined: Fri Jul 28, 2017 4:11 am

Re: Unitrol 800 series siren power output transistor question

Tue Aug 08, 2017 5:38 am

Unitrol 800 project update. So far so good. I was able to get the siren working today by replacing the dead SP3099 output transistors with Mospec 2N5683 PNP transistors. Powered up the unit and had full siren audio output. Tried the PA function but only heard clicking noises in the speaker when pressing the PTT switch on the federal signal mic i was using to test. Any ideas why no mic audio even though the volume control is at full right? Is a federal signal mic incompatible with this unit? Also how would i hook up a momentary switch so i can use the manual siren function? I know it involves the horn ring connections on the back of the unit but i don't have an installation manual to explain the wiring. Any more help would greatly be appreciated. Thank you so much.
-Mike

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