why hiss in my wireless mic system?

[BboB]

I know the answer might seem obvious (getting closer, checking
connections, etc) but this has me stumped. I recently acquired an older
170 Mhz based Radio Shack wireless mic and receiver for an upcoming
event. I got it off of the bay and it was advertised as fully
operational, but of course it wasn't. There was no audio upon receipt,
and I had to change the mic wire from the electret clip on, to the
transmitter. That got it going, but I notice that I have a lot of hiss
in the receiver. I've tried moving closer, and I still have the hiss.
If I turn off the mic (put on standby), I still have hiss, although a
bit weaker as I was obviously getting some hiss from the mic which was
expected. However, the hiss that remains stumps me and I shouldn't be
getting it. Audio seems to be coming from the receiver fine, but with
the amount of hiss, I don't think I'm going to be able to use this for
the intended purpose.

I welcome any suggestions here to solve this.

Thank you!

[Peter W.]

Typically, hiss of the nature you describe - not related to transmission/reception - is due to a failing driver or output device in the audio section. Since it is most likely that these functions are on a single chip, and unless that chip is able to be identified and easily changed, you are right in your diagnosis. As it is obviously defective, you should go ahead and return it if possible.

Without being judgmental, I never purchase anything from 'the bay' on the expectation that it actually works as described. Nor would I sell anything (a very rare occurrence) that I describe as 'working'.

Peter Wieck
Melrose Park, PA

[Phil Allison]

BboB wrote:
=============

** You sure the frequency is clear ?

You might have a conflict with a DTV station.


..... Phil

[BboB]

What this turned out to be was somehow caused by the preamp. I switched
out the preamps and problem solved. There must be instability in the
original preamp somewhere. You were right, definitely audio related.
Thanks for the help.