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Channel width and broadband amplifier (N1275A)

Posted: Thu May 24, 2007 4:00 pm
by oz_com
Hope this isn't too bad of a newbie question :-)

Suppose I have a newer, narrowband HT with 12.5 kHz spacing, such as the P1225, and hook it to a broadband amplifier such as the N1275A or NLE8912A (450-470 MHz).

Would the output still be narrow-banded, or would such an amp somehow expand the channel width? Is there any way a broadband amplifier introduces any other kind of unwanted signal characteristics?

Sorry that's actually two questions... Any takers?

Tim

Posted: Thu May 24, 2007 4:51 pm
by Wowbagger
It's better to ask questions and learn than to remain ignorant.

So as long as you are not overloading the amplifier, and driving it non-linear, it shouldn't alter the signal.

More on N1275A power amp tuning

Posted: Thu May 24, 2007 5:58 pm
by oz_com
Thanks! I'll take advantage of good traffic on my post and bump it:

Recently I was told that these amps can be tuned outside the nominal bandsplit, by adjusting an internal trimmer for max power output when applying the desired frequency. The service literature, on the other hand, calls for using a signal generator at a specified frequency.

Generally, is there any harm (or harmonics, etc.) caused by re-tuning it to a frequency of one's choosing? Is there some kind of "FCC check" that can be done on these amps?

Again, all input appreciated,

Tim

Posted: Thu May 24, 2007 6:56 pm
by Bruce1807
you sort of answered your own question.
Tuning a PA OOB without the proper stuff like a spectrum analyser may cause all sorts of grief with spurious but then again you may be lucky.
Simply put the PA is designed for a band and filtered to limit spurious in that band, take it out of that band and who knows.