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 Post subject: When the broadcast station has a 'problem'.
PostPosted: Nov Fri 17, 2017 10:52 am 
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Joined: Sep Sun 04, 2016 9:26 am
Posts: 32
Location: North Queensland, Australia.
G'day all, with apologies to Apollo 13, our main local AM broadcast station had a fairly significant outage the other morning, apparently with issues with equipment at the transmit site, which was resolved with equipment replacement after some hours.

An interesting result that may have existed previously without being overly noticed before the actual outage! The transmit audio quality is now vastly improved, and in fact my old reliable MK484 AM tuner now sounds very hi fi! I'm going to try and find out what the technical issue actually was, however in any case, things sound really good now! Regards, Felix (vk4fuq).


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Nov Fri 17, 2017 6:58 pm 
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Joined: Feb Sun 02, 2014 9:13 pm
Posts: 1653
Location: Roanoke, VA
When you post a follow up please be as technical as feasible. I will be able to elucidate for those not familiar with broadcast equipment as I have been a radio station engineer for nearly 50 years.

Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcityeng/index.html


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Nov Fri 17, 2017 11:24 pm 
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Joined: Apr Thu 14, 2016 8:25 pm
Posts: 282
Location: pensacola fl
Hi Felix. Did the station install new processing equipment? Did Australia impose new standards on the am broadcasters there? Here in the U.S. we adopted the NRSC standard which imposes a modified 75us pre emphasis curve. This would make the high end get through narrow banded tuned circuits. Our system has a brick wall filter at 10KHZ.


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Nov Sun 19, 2017 9:00 pm 
Member

Joined: Sep Sun 04, 2016 9:26 am
Posts: 32
Location: North Queensland, Australia.
G'day all, I've just been informed that the issue was the Optimod (processor) failure. Apparently it was faulty but still 'working' for some time beforehand. Regards, Felix (vk4fuq).


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Nov Sun 26, 2017 1:10 am 
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Joined: Jun Wed 08, 2011 2:33 am
Posts: 6082
Location: Ohio 45177
I have heard plenty of failures and dead air from stations in the region here. Sometimes it takes awhile to come back. Probably part of the reason is their engineering is usually on-call contract or such, no money for on-duty engineers at stations anymore, I suppose. And no official requirement for that.


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Nov Sun 26, 2017 2:22 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 10966
Location: Mpls, Minnesota
For $8000.00 you would think they would have a spare processor on hand.
https://www.orban.com/optimodam-9400-3

Dave


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Dec Sun 03, 2017 6:38 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3381
Location: Monterey California USA
We could have a separate thread on what goes wrong at AM broadcast stations (FM for that matter too.

Some examples. Summer once in another life, I am filling in for a buddy who was contract engineer on vacation. Local 1 KW AM mom and pop says transmitter on the air but no program material. I go there on a Sunday morning at 0700. Telco leased line to studio dead. I tell the manager we have to call AT&T. Oh, but I know why it is dead, he protests. Want to share? Well, he hadn't paid the bill in 6 months and they finally disconnected it.

Same station, 2 months later. Super hot summer day. Transmitter off the air. I find the breakers tripped and see the top panel of the transmitter was not on and lying in a corner. Interlocks defeated. Seems the helpful DJ had found the PA compartment fan had failed and had taken a table fan he got at Walmart and propped it over the PA pointing down inside. Some hours later the fan had vibrated enough to plunge off the rack cabinet edge into the now open PA compartment. With obvious results. :x

Same summer, the VSWR trip-out on the transmitter had activated. Upon arrival found alarms lit for VSWR. lightning and overtemp. Reason? A rattlesnake had gotten into the antenna tuning box and wrapped himself around the large coil. He was half cooked but the rest of him was still lethal. His remains are nailed to the wall on the back of the transmitter building wood siding as a warning to others.

_________________
WB6NVH
California Highway Patrol Radio
Bell System Mobile Telephone History
http://www.wb6nvh.com


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 Post subject: Re: When the broadcast station has a 'problem'.
PostPosted: Dec Sun 03, 2017 7:03 pm 
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Joined: Feb Sun 02, 2014 9:13 pm
Posts: 1653
Location: Roanoke, VA
Geoff Fors wrote:
We could have a separate thread on what goes wrong at AM broadcast stations (FM for that matter too.

Don't get me started - I've been battling such problems for nearly 50 years.

Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcityeng/index.html


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