kk7u_seattle wrote:
Thanks for your reply. Correct me if I am wrong, but in order to make the audio sound
"normal" through the Phase Modulated transmitter I have to engage the de-emphasis
network on my controller circuit board. If I feed flat discriminator audio into the PM
exciter it ends up getting double-emphasized which makes the audio sound strange.
Correct....
So my question is specific to the GE Mastr II. I suspect that the receiver setup in a stock
Mastr II de-emphasizes the audio because it's designed to work with the PM exciter which
adds emphasis as a function of how it modulates. Further I suspect that the GE Mastr II
FM exciter is designed to be a drop-in replacement, which leads me to believe that the FM
exciter board has pre-emphasis circuitry on board.
Correct....
I've found the LBI that describes the FM transmitter and it does appear to run the audio
through a pre-emphasis network.
I am pretty new at this so I'm not very good at looking at the schematic and figuring out
where to physically inject flat audio into the FM exciter to skip the pre-emphasis network.
I am wondering if anybody familiar with the GE Mastr II and the FM exciter has done this
before to run the repeater with completely flat audio?
Shameless Plug:
What we do at Repeater Builder (the company) is use a little audio
processor board called the AP-50. This will allow you to properly
deploy "flat audio" through the repeater system audio chain and use it
to drive the FM modulator directly /with the addition of peak limiting
and splatter filtering./
Here are some links:
<http://www.repeater-builder.com/products/ap-50.html>
<http://www.repeater-builder.com/ge/mastrII/ap-50-fm-mastr2.html>
Hope this helps...
Kevin Custer
