Search found 49 matches

by jthorusen
Thu Nov 14, 2019 9:01 pm
Forum: AM Radio
Topic: Collins 820E-1/F-1 Screen Transformer
Replies: 11
Views: 661

Re: Collins 820E-1/F-1 Screen Transformer

I can't find any detailed info on the Collins 820E series transmitters on line. Does this transmitter use the grounded screen technique where the screen supply is effectively in series with the plate supply and has to supply as much current as the plate supply does, thus necessitating a really hefty...
by jthorusen
Sun Oct 20, 2019 8:36 pm
Forum: Ask the Engineers
Topic: Recommendations for EAS box?
Replies: 5
Views: 530

Recommendations for EAS box?

Here is a quote from RadioWorld on-line news: Now, an effort to maintain compliance with commonly accepted security standards, FEMA is also taking the next step of removing support for older methods by requiring the use of an updated TLS 1.2 protocol to access FEMA’s IPAWS server, said Sage Alerting...
by jthorusen
Sat Aug 24, 2019 1:22 am
Forum: Everything else
Topic: Proposal XML
Replies: 9
Views: 259

Re: Proposal XML

Just submit it as a Word document in .XML format. Then, if they complain, tell them they don't have the latest version of the software and let their IT guys go nuts for a change. :D
by jthorusen
Sat Aug 24, 2019 1:16 am
Forum: TV Engineering
Topic: Definition of a heartstopper
Replies: 6
Views: 634

Re: Definition of a heartstopper

I seem to recall it was a spot for a Cannon color copier that had bars and tone. That used to get my attention even though I was at the transmitter and couldn't do a thing about it.

Regards,
by jthorusen
Wed Aug 21, 2019 8:33 pm
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 494

Re: Belar FMS-2 Meters

According to what I read, it uses two sound cards. One is used to convert local analog audio to a digital format. This can be eliminated by using an internal audio source such as a media player as the signal source. This is converted to a 192 KHz digital data stream which is software converted by th...
by jthorusen
Mon Aug 19, 2019 12:49 am
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 494

Re: Belar FMS-2 Meters

Hi Chuck:

To quote Artie Johnson, "Verrry Interesting!" :D

I will look into this.

Thanks,
by jthorusen
Sat Aug 17, 2019 9:09 pm
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 494

Re: Belar FMS-2 Meters

Re Bessel nulls: This is something I wrote a paper on when I still worked for CBS. I am quite familiar with the technique; I used it to calibrate the TFT-723 Main / Mono modulation monitor now in service at the station. Dale was kind enough to send me the NAB instructions for an FM stereo proof, and...
by jthorusen
Fri Aug 16, 2019 6:01 pm
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 494

Re: Belar FMS-2 Meters

For Bob M.: That's how I determined the meter linearity. Weston lab standard 0-1 mA mirrored scale milliammeter in series with a 22K resistor and my low voltage bench power supply. 400 uA full scale (spec for the Belar meters according to what is printed on their scale cards) is roughly 10 volts fro...
by jthorusen
Thu Aug 15, 2019 5:45 pm
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 494

Re: Belar FMS-2 Meters

Not to worry.... I don't have the bucks to replace the meters. Based on earlier comments by Bill and Dale I think the meters are supposed to sit on zero with no power applied. So, I removed the front panel and the meters, adjusted the second hair spring position and got the meters to zero nicely. I ...
by jthorusen
Tue Aug 13, 2019 11:45 pm
Forum: Ask the Engineers
Topic: Belar FMS-2 Meters
Replies: 13
Views: 494

Belar FMS-2 Meters

I recently acquired a Belar FMS-2 stereo modulation monitor. Looks like a nice clean unit, although it is an early version (slide switch to select AC line voltage). My question is this: Both meters are pinned off-scale low with no power applied to the unit. I know that sometimes meters are deliberat...
by jthorusen
Sat Aug 10, 2019 7:37 pm
Forum: FM Radio
Topic: National EAS Test
Replies: 16
Views: 573

Re: National EAS Test

RodeoJack's comments have a lot of validity, it seems to me. However, since I am taking care of a low power FM station, the issue does not arise. All of our audio processing is done in the station automation computer. From there, an analog audio output (Left and Right) goes to the EAS decoder, then ...
by jthorusen
Wed Aug 07, 2019 3:56 pm
Forum: FM Radio
Topic: National EAS Test
Replies: 16
Views: 573

National EAS Test

Moderator: I'm not sure if this belongs here or in the FCC board; if inappropriate, please move.

Well.... we made it. A successful national EAS test performance by KWPB-LP. (First time.)

How did it go for the rest of y'all?

Regards,
by jthorusen
Wed Jul 31, 2019 4:56 pm
Forum: AM Radio
Topic: LPB Output Transistors (SD-1407 Matched Pair)
Replies: 7
Views: 797

Re: LPB Output Transistors (SD-1407 Matched Pair)

Sorry Dale.

I misread the post. I interpreted LPB to mean Low Power (insert FM) Broadcast transmitters... and I had worked on one of those recently.

Please disregard all after "I hate radio..." :D

Regards,
by jthorusen
Tue Jul 30, 2019 7:23 pm
Forum: AM Radio
Topic: LPB Output Transistors (SD-1407 Matched Pair)
Replies: 7
Views: 797

Re: LPB Output Transistors (SD-1407 Matched Pair)

The last time I went through this rigamarole (different device), I couldn't get the new FET to stop flying if the load had even a smidgeon of +j. I ended up replacing the whole assembly with a pallet from Broadcast Concepts. Installed easily and ran just fine out of the box... end of problem. Many t...
by jthorusen
Wed Jul 17, 2019 12:16 am
Forum: Ask the Engineers
Topic: Cutting Hard Line
Replies: 12
Views: 366

Re: Cutting Hard Line

I used to use a tubing cutter for 3 1/8 on TV channel 2 (54-60 MHz). I also used a deburring tool to take the inward sharp edge off. I never had any difficulties at that frequency. As I recall, we ran about 15 KW peak sync. I can't remember whether or not I ever cut any hard line for the FM station ...