Search found 49 matches

by DaveSt
Thu Apr 04, 2019 1:52 pm
Forum: STL Engineering
Topic: RDS options
Replies: 15
Views: 821

Re: RDS options

That is absolutely true... However, I don't really see any reason that a line of ad text rotating onto the radio display every few minutes would alienate listeners. Well other than DT... It's not like they blast off at double volume in the middle of your favorite tune the way audio commercials do. ...
by DaveSt
Mon Apr 01, 2019 1:30 pm
Forum: STL Engineering
Topic: RDS options
Replies: 15
Views: 821

Re: RDS options

If you just need to get RS232 data over an IP connection, then Lantronix make some good boxes for that. The UDS1100 for example.
by DaveSt
Fri Feb 22, 2019 11:48 pm
Forum: TV Engineering
Topic: Adding Genlock
Replies: 39
Views: 1154

Re: Adding Genlock

I think you are correct. Just lock up all the sources and the Tricaster.
by DaveSt
Fri Feb 15, 2019 2:21 am
Forum: FM Radio
Topic: Optimod 2200
Replies: 6
Views: 632

Re: Optimod 2200

The A/D and D/A converters can cause problems on these older Orban products. Usually they just die, but what you describe is possible. You can find them on Ebay or I think Orban will still repair these units. The 2200's are still well worth repairing. Personally I think they were the best processor ...
by DaveSt
Tue Feb 12, 2019 10:20 am
Forum: Ask the Engineers
Topic: Cablewave 738350 3-1/8" EIA Flange (pressurization)
Replies: 2
Views: 282

Re: Cablewave 738350 3-1/8" EIA Flange (pressurization)

The transmitter end is good. It had occurred to me that I could replace them with connectors that will pass the pressurization. I could do what you suggest also. I was hoping to do something that did not mean a significant break in transmission though and was easy!
by DaveSt
Tue Feb 12, 2019 6:43 am
Forum: Ask the Engineers
Topic: Cablewave 738350 3-1/8" EIA Flange (pressurization)
Replies: 2
Views: 282

Cablewave 738350 3-1/8" EIA Flange (pressurization)

Hello all. In a month or so I have to return to a site to do some repairs on the pressurization system. I was there last month and the dehydrator had failed from old age and because the feeder would not pressurize, so it had run until it died. The dehydrator will be replaced as it is too far gone. T...
by DaveSt
Mon Feb 04, 2019 1:44 am
Forum: FM Radio
Topic: High Reflected Power Puzzle
Replies: 33
Views: 1617

Re: High Reflected Power Puzzle

To properly shut down the amplifier with the bias, it is not sufficient to remove the bias voltage. It needs to be driven to a negative voltage of several volts. For the harmonics, usually the output filter after the pallet will have elliptical sections to knock out the second and 3rd harmonics and ...
by DaveSt
Fri Jan 25, 2019 11:21 am
Forum: Digital Television
Topic: Troubles in SFN network
Replies: 1
Views: 180

Re: Troubles in SFN network

DVB-T is a lot less robust than DVB-T2 in this situation. Getting the modulation to be identical with different modulators will be a challenge. I would say you have two priorities. 1. You need to be able to remote control/monitor the transmitters so that you can see any alarms such as loss of synchr...
by DaveSt
Thu Jan 24, 2019 12:32 am
Forum: FM Radio
Topic: HT-10 APC issues
Replies: 12
Views: 778

Re: HT-10 APC issues

I do not know this transmitter model or your test setup, so I might be pointing out the obvious. Are you measuring the AM with a dummy load or into antenna? A narrowband antenna/filter will cause poor AM measurements. Especially so if the measurement point is not the forward port of a good direction...
by DaveSt
Thu Dec 20, 2018 8:41 am
Forum: FM Radio
Topic: PC Software for Audio Processor for FM translator ?
Replies: 10
Views: 509

Re: PC Software for Audio Processor for FM translator ?

I have had very good luck with HP Z400 workstations used for both on-air and production. You can get them with loaded with Windows 7 and >8 GB RAM often for <$200. I probably have about eight of them now. They are very well made (much better than consumer grade) and very stable. Corporations used t...
by DaveSt
Sun Dec 16, 2018 2:40 am
Forum: FM Radio
Topic: High Reflected Power Puzzle
Replies: 33
Views: 1617

Re: High Reflected Power Puzzle

I had a quick look at the transmitter manual for what you have. It uses the FM300-108 pallet which is a very common pallet and was used by many transmitter manufacturers before it became obsolete. It is generally very stable. There is also a trimmer on the input side for the bias which should give a...
by DaveSt
Sat Dec 15, 2018 5:37 am
Forum: FM Radio
Topic: High Reflected Power Puzzle
Replies: 33
Views: 1617

Re: High Reflected Power Puzzle

You might expect a gate voltage closer to 2.6V. From what you have said about that transmitter, you risk spending a lot on spares and on your time with no guarantee of a good result. You might be better putting those costs towards a new transmitter with a warranty.
by DaveSt
Thu Dec 13, 2018 2:55 am
Forum: FM Radio
Topic: High Reflected Power Puzzle
Replies: 33
Views: 1617

Re: High Reflected Power Puzzle

It looks like the PA is oscillating by itself, which is not unusual in some PA designs. If the drive to the PA section is removed, most likely it will carry on oscillating. When the MOSFET was changed, if the bias current was not set correctly then that can make the PA more likely to take off like t...
by DaveSt
Wed Dec 12, 2018 12:23 pm
Forum: FM Radio
Topic: Harris Z FM Diagnostics Failing
Replies: 4
Views: 330

Re: Harris Z FM Diagnostics Failing

With any diagnostic system there is always the possibility that the fault indicated is caused by something unrelated to the error shown. It is worth checking everything else in with the transmitter and its output to make sure they are good. If you have a test load, try the diagnostics with it runnin...
by DaveSt
Wed Dec 12, 2018 1:37 am
Forum: FM Radio
Topic: High Reflected Power Puzzle
Replies: 33
Views: 1617

Re: High Reflected Power Puzzle

The problem with the design of antenna you have is that they are extremely narrow band. That can be quite challenging for any transmitter to drive. It increases the likelihood of instability in the transmitter PA. That may also have been made worse after the change in transistor. The instability wil...