[Tech-Assist] Moseley SL9003Q

[Mike McCarthy]

Let's try this again....

As a rule, I never install a 9003 without a TXRX bandpass filter in 
front of the RX. The RX is broad as a barn door and easily desensed. 
The Bp filter cleans up SO MUCH grunge and BER issues that it's an 
automatic include with the purchase. So much so that a Cresend amp might 
not be needed as the amp might actually hurt more than help.

100% agree about needing more debugging aids.

MM

On 7/4/2011 12:25 PM, Gregory Muir wrote:
> Ah, the dreaded Moseley StarLink!
>
> In reference to your unit, check receive signal level first.  If greater
> than -70 dBm (-50 to -60 ideal range) then receiver should be hearing the TX
> well.  One note on these units - if the receive signal level is lower, they
> become very sensitive to other STLs operating in the area even if they are
> several channels away from yours.  This appears to be a byproduct of the
> wide bandwidth of the receiver and the use of very high density QAM encoding
> (128Q in the unit I was working with).
>
> As far as the TX is concerned, check output with a Bird!!  Don't trust the
> internal display.  The TX output is supposedly protected with an ALC circuit
> which will cut back the power in the event of a TX output port fault which
> may depress the received signal level to where the receiver is incurring a
> high BER due to poor S/N.  Remember - the wider the receive bandwidth, the
> higher the received noise level..
>
> It's too bad manufacturers don't bring out the I/Q IF signals anymore for
> connection to a modulation analyzer.  One look at the constellation on the
> display one of  these units will tell volumes about what is happening.
>
> Gregory Muir
>
> Wolfram Engineering, Inc.
> Great Falls, MT
> 406-799-5679
>
>