Search found 13 matches

by DaveSt
Mon Nov 12, 2018 12:47 am
Forum: Broadcast Engineering News
Topic: Tiger Mountain (WA) master antenna catches on fire
Replies: 12
Views: 337

Re: Tiger Mountain (WA) master antenna catches on fire

Makes a case for a split feed to the panels. Most master antenna systems I've been involved with have a line to the top half and a line to the bottom half that can isolated in case of a failure. ...Lee The photos do show a dual feeder arrangement for this system. With the amount of damage that woul...
by DaveSt
Sun Nov 11, 2018 1:26 am
Forum: Broadcast Engineering News
Topic: Tiger Mountain (WA) master antenna catches on fire
Replies: 12
Views: 337

Re: Tiger Mountain (WA) master antenna catches on fire

No VSWR shutdown? Depends on what type of combining system is in use. In a balanced combiner system the TX won't see any VSWR mismatch coming from the antenna. I've always wondered why it's not common practice to monitor the VSWR of the combined output, where antenna faults can be detected and tran...
by DaveSt
Sat Nov 10, 2018 3:15 pm
Forum: Broadcast Engineering News
Topic: Tiger Mountain (WA) master antenna catches on fire
Replies: 12
Views: 337

Re: Tiger Mountain (WA) master antenna catches on fire

It is hard to imagine the failure mode that could have caused all that damage to every panel. It's a lot of RF and on 6 channels, so lots of volts too. Maybe a VSWR issue causing voltage breakdown at the antennas? Some clear photos here: https://www.radioworld.com/news-and-business/tower-fire-disrup...
by DaveSt
Sat Oct 06, 2018 9:44 am
Forum: STL Engineering
Topic: RVR PTRL-LCD transmitter PS
Replies: 7
Views: 504

Re: RVR PTRL-LCD transmitter PS

An old saying: Google is your friend, or in this case Bing. A search for the power supply part number finds this manual: http://3-mtr.info/manuals/RVR/TEX30LCD/M2TEX30LCD28NS.pdf The TEX30 has the same PSU and has the circuit diagrams you need. For safety, check R4 first and make sure there is no vo...
by DaveSt
Fri Oct 05, 2018 12:22 am
Forum: STL Engineering
Topic: RVR PTRL-LCD transmitter PS
Replies: 7
Views: 504

Re: RVR PTRL-LCD transmitter PS

The circuit diagrams for the supply are not in the manual. There is a good chance that RVR will not even have them. In additions to the checks mentioned earlier, look for a high value resistor on the primary side of the supply. It will be connected to the unregulated DC supply capacitor and provides...
by DaveSt
Wed Sep 05, 2018 9:00 pm
Forum: FM Radio
Topic: Synchronizing FM over IP?
Replies: 11
Views: 554

Re: Synchronizing FM over IP?

The delay needs to be kept within microseconds. The article I mentioned earlier is available here: https://www.waveart.it/leggi-news?id=51 . It is pretty good as they have understood what is needed well and have verified it with tests. To keep the modulation identical, they also say that the composi...
by DaveSt
Wed Sep 05, 2018 1:21 pm
Forum: FM Radio
Topic: Synchronizing FM over IP?
Replies: 11
Views: 554

Re: Synchronizing FM over IP?

The synchronisation you need is very high, so you really would have to use something like GPS. The modulation needs to be identical at all sites and that is far from easy. An Italian manufacturer published some research on this quite recently. You also have to worry about the delay between the diffe...
by DaveSt
Sun Aug 12, 2018 10:49 pm
Forum: FM Radio
Topic: FM Radio Broadcasting Data System
Replies: 8
Views: 286

Re: FM Radio Broadcasting Data System

There are a few things that can affect RBDS reception other than a weak signal or multipath. Most obviously the RBDS subcarrier level needs to be correct. That would typically around 3kHz. Too high is just as bad as too low. There are various mod monitors that can measure that directly. Then anythin...
by DaveSt
Thu Aug 02, 2018 1:36 pm
Forum: FM Radio
Topic: HARRIS DIGIT EXCITER
Replies: 6
Views: 249

Re: HARRIS DIGIT EXCITER

Check the electrolytic caps in the PA unit, in particular C29 (82u/63V). If a 47u is fitted, change it. You can break the old one so that you do not have to remove the board.
by DaveSt
Sat Jul 28, 2018 12:34 am
Forum: STL Engineering
Topic: Nicom 900 link - STL Antennas Can you Mix and Match
Replies: 18
Views: 667

Re: Nicom 900 link

The performance of a receiver can be different with a very weak signal strength. So appearing to work better with a 0.1MHz offset may not be an indicator of any problem. If you are old enough, recall the days of analogue radios in cars. You often had to tweak the tuning as you moved to areas with we...
by DaveSt
Tue Jul 24, 2018 1:12 pm
Forum: FM Radio
Topic: Processing Pre or Post STL?
Replies: 15
Views: 378

Re: Processing Pre or Post STL?

Doesn't the 2200 have a serial port for remote control? You could put an IP to serial converter at the midpoint for remote control, if you have IP access at the midpoint. Just a GPIO port with pins you can use to select processing presets. No possibility for serial comms as I recall. Not that there...
by DaveSt
Tue Jul 24, 2018 2:15 am
Forum: FM Radio
Topic: Processing Pre or Post STL?
Replies: 15
Views: 378

Re: Processing Pre or Post STL?

Hey Guys, Thank you so much for all the info thus far......... So the opinion so far seems to be don't move it back in the chain, if anything the actual best thing to do would be to move the Optimods from the mid point relay station where it goes from fibre to STL & put it right before the lovely n...
by DaveSt
Mon Jul 23, 2018 2:30 pm
Forum: FM Radio
Topic: Processing Pre or Post STL?
Replies: 15
Views: 378

Re: Processing Pre or Post STL?

I have been lurking here for a while and have finally decided to register. So hello everyone! it is good to find a forum with some friendly professional discussion. Answering the question, by far the best connection from an audio processor to the transmitter is composite. You really don't want to dr...