[BC] Problems that make you want to scream!

[cldube]

----- Original Message ----- 
From: "Alan Alsobrook" <radiotech at bellsouth.net>
To: "Broadcast mailing list" <broadcast at radiolists.net>
Sent: Wednesday, October 12, 2005 1:51 PM
Subject: [BC] Problems that make you want to scream!


> when it just came back on it's own. So... I take a wait and see attitude.
Ok- so it's intermittant (I love those).

> transmitter is on we have no audio. Here we go again, I get down their as 
> fast as I can. I find the following The STL receiver has no receive 
> signal, looking at the STL feed line with the SA I see other STL signals
Since the SA didn't see YOUR carrier- we know you're not transmitting at 
this point.

>studio problem.. When I get inside the STL transmitter has no rf output. 
>Since I brought another STL-10 with me I quickly pull them apart and swap 
>crystals and tune up the backup transmitter. Slip in in the rack and turn 
>it on, everything looks fine except still no audio.
Can you check your reflected power during failure times? This will confirm 
whether or not
the tx antenna system is involved.

>  Dash back to the tower to  check, Nope it's hooked up and nothing.. Of 
> course I didn't bring the SA with me, it's at the studio where I was 
> setting up the STL transmitter.
Did you see any receive signal indication at this point?

> Go back to the studio and sweep the STL line and antenna, they don't look 
> great, but appear to be ok. Recheck the freq of the STL
Again- any vswr indication?

> Load up everything to go back to the tower site, do another parking lot 
> check and yes the STL is there and seems to have good signal. Drive 
> towards the transmitter site, just as I'm getting to the last turn thump 
> thump thump audio..

Since we now know that you are transmitting (do you have a scanner or 
something to confirm you
are modulating your STL 100% of the time?), at least that you have a 
carrier, confirm that at your receive antenna
and then focus on the signal path from that antenna backwards. Unfortunately 
it'll probably have to fail again before you can find the
trouble. You have changed one potential failure point- the transmitter. If 
your cable and antenna seem OK and can't be forced into failing at the 
studio end, you can now focus your energies on the receiving end. Obviously 
this is a case of multiple faults happening, each one resulting in the same 
thing- an unreliable STL.

Chuck Dube
Amherst