Re: UBITX filter bandwidth ?


Sandeep Lohia
 

Change ECM  & try...


On Wed, May 23, 2018, 4:32 AM Ralph Mowery <rmowery42@...> wrote:
Has anyone measured the bandwidth of the uBITX filter ?  

I have tried it two ways. one with a SA/TG at the 12 mhz filter, and another by feeding in a audio tone from 200 hz to 2800 hz into the mic input from a function generator and using a wattmeter..  Both ways seem to give me a 3 to 6 db bandwidth of about 1600 hz.  

The receive audio seems ok to me, but several hams I talk to almost every day say the audio is not very good, like it is restricted.  I tried moving the BFO up and down about 100 hz at a time to get the best and they tune for the best signal from me incase the frequency is not exact.  

I did change to a Baofeng hand mic and the audio was somewhat better.  I am waiting on some parts to come in to repair a Shure desk mic to see how it sounds.  I am using a similar mic on my Icom 746pro.  I tried feeding my Drake L4B amp and getting around 150 watts out so the signal level is up the about the same as the Icom.  The audio did not seem to change when running the amp or not except it was stronger as it should be.

de ku4pt

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