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Public Safety Saber Mic for Saber

Posted: Sun Jan 23, 2005 11:52 pm
by Timmuc
Can I use a P/S Mic for my VHF radio ore just for UHF radios?

Tim

Posted: Mon Jan 24, 2005 7:26 am
by Keygun
Ja, natürlich. Solange Du eine für den Frequenzbereich passende Gummiantenne auf das Mikro schraubst, ist das kein Problem.

Yes, shure. It only depends on the rubber-antenna which ich screwed to the PS-mike.

Keygun

Posted: Mon Jan 24, 2005 8:29 am
by larryepage
Not quite true. The speaker mic does not provide a sufficient ground plane for operation on VHF frequencies. Performance will likely be less than you expect, and it puts the PA at risk, due to the resulting antenna loading mismatch. So this is not a recommended practice...

Regards,

Posted: Mon Jan 24, 2005 9:06 am
by jedi_saber
Keygun wrote:Ja, natürlich. Solange Du eine für den Frequenzbereich passende Gummiantenne auf das Mikro schraubst, ist das kein Problem.

Keygun
Schoen zu sehen dass dieses Forum nun auch zweisprachig ist. :P

Posted: Mon Jan 24, 2005 11:10 am
by Keygun
To have the right amount of ground plane, is always an big problem on handhelds, unless you use "closed" antenna systems (dipoles for example), which don`t need to use the radios body as the second half of the antenna. I guess, a handheld radio with a PS-mike attached, provides more "ground plane", than the radio alone, when the antenna is directly screwed to it. Nevertheless in most cases, the VSWR of the rubber duckie is still very bad. But the handheld-radios PA is designed for that kind of load conditions and must stand it without complaining. The only thing that should be observed: Maybe some kind of frequency band dependent tuning circuit sits within the housing of the PS-mike. But all of the PS-mikes (made by Mot) i have seen in the past, are straight "cable-to-plug" with no tuning circuits.

Keygun

Posted: Mon Jan 24, 2005 3:39 pm
by billy7834
What about the the type of speakermike that does not have the antenna attached to it but to the radio itself?

Posted: Tue Jan 25, 2005 2:48 am
by Keygun
It´s the same. Every attached accessory becomes part of the antenna
system ("ground-plane") and has rf-current creeping around on it.

Keygun