Search found 848 matches

by Dale H. Cook
Tue Jan 29, 2019 11:09 am
Forum: From the Trenches
Topic: Sync, time code, and insanity
Replies: 7
Views: 395

Re: Sync, time code, and insanity

... so the system's RF performance is independent of the cable length. That is my case as well, but my mom-and-pop radio clients don't need GPS. I use it only in the Explorer to control my police/fire/EMS scanner. As I drive around the scanner switches, based on location, to whatever radio systems ...
by Dale H. Cook
Tue Jan 29, 2019 8:05 am
Forum: From the Trenches
Topic: Sync, time code, and insanity
Replies: 7
Views: 395

Re: Sync, time code, and insanity

Fortunately, the master clock came back to life after being unplugged and restarted -- but not without blurting out about fifteen minutes of the wrong time, before it acquired enough satellites to lock back up and rejoin reality. It should not take that long for a GPS which is already in service to...
by Dale H. Cook
Thu Jan 24, 2019 6:35 am
Forum: FM Radio
Topic: HT-10 APC issues
Replies: 12
Views: 651

Re: HT-10 APC issues

I will second Fossil and Dave. I have seen AM noise increase with IPA problems, and you need to measure it into a good dummy.

Two questions, which may help find the cause: 1) Is this synchronous or asynchronous noise? 2) Have you looked at the noise on a 'scope?
by Dale H. Cook
Tue Jan 01, 2019 12:24 pm
Forum: AM Radio
Topic: Gates One Blows PA Fuses w/ Modulation
Replies: 25
Views: 1218

Re: Gates One Blows PA Fuses w/ Modulation

engnewbie wrote:
Tue Jan 01, 2019 12:10 pm
Does a fluke 87 have enough voltage to turn on the MOSFETS when testing?
I expect so. I use a vintage Beckman DMM that works fine for testing MOSFETs.
by Dale H. Cook
Tue Jan 01, 2019 8:01 am
Forum: AM Radio
Topic: Gates One Blows PA Fuses w/ Modulation
Replies: 25
Views: 1218

Re: Gates One Blows PA Fuses w/ Modulation

Here's a note out of left field. Although it has been over 30 years since I worked on an SX series transmitter, and I have never worked on a Gates series transmitter, I have worked on a lot of other solid state transmitters in those decades. Some output transistors, especially flat-pack power MOSFET...
by Dale H. Cook
Fri Dec 28, 2018 10:33 am
Forum: Ask the Engineers
Topic: NEC4.2 Accuracy in the Calculation of Radiated E-M Fields
Replies: 3
Views: 305

Re: NEC4.2 Accuracy in the Calculation of Radiated E-M Fields

I can read it fine on my laptop without even having to zoom in on the image.
by Dale H. Cook
Fri Dec 28, 2018 10:25 am
Forum: On-Air Studios
Topic: Auditronics 200 210 or 212 manual
Replies: 6
Views: 1276

Re: Auditronics 200 210 or 212 manual

RGORJANCE wrote:
Fri Dec 28, 2018 8:24 am
... that thing's been a "brick".
"Brick" is a term that I have long heard for reliable equipment. In engineering terms, what is the antonym for "brick?" I would suggest "sponge," something that soaks up money by way of of parts, engineering time, and lost revenue.
by Dale H. Cook
Wed Dec 26, 2018 9:48 am
Forum: Everything else
Topic: HOLIDAY GREETINGS
Replies: 2
Views: 120

Re: HOLIDAY GREETINGS

The same to you, Fossil, and mine was quiet and spent with family. I've told my customers that I may be unavailable for a couple-few days as the Explorer is going in for its annual overhaul and inspection, and there are a number of things that need attention. I drive my Explorers until the wheels ar...
by Dale H. Cook
Sun Dec 23, 2018 9:23 pm
Forum: AM Radio
Topic: LPB Output Transistors (SD-1407 Matched Pair)
Replies: 3
Views: 246

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

The price for a matched pair at Mouser is not bad considering that they get about $70 for singletons. For the labor that it would take me to match singletons my clients would be better off with factory matched pair. I have one client who stocks spares - I need to let them know that there will likely...
by Dale H. Cook
Sun Dec 23, 2018 11:09 am
Forum: AM Radio
Topic: LPB Output Transistors (SD-1407 Matched Pair)
Replies: 3
Views: 246

LPB Output Transistors (SD-1407 Matched Pair)

Does anyone else here work on LPB transmitters? If so, what are you doing for output transistors (SD-1407 matched pair) now that RF Parts is out of them and they are no longer available from SGS-Thomson? Mouser is showing Advanced Semi SD-1407 matched pair for almost $150 per pair with 6 week lead t...
by Dale H. Cook
Tue Dec 18, 2018 6:14 am
Forum: Ask the Engineers
Topic: What is this? Broadcast Amplifier Transmitter?.paper weight?
Replies: 6
Views: 342

Re: What is this? Broadcast Amplifier Transmitter?.paper weight?

Note that this dummy is oil-filled, which is typical for units rated 1 -2 kW or less. I think the largest oil-filled dummy I've seen is 2.5 kW, a reject load for a TV transmitter. The type of oil used is critical for heat dissipation at the load's rated maximum. Dow-Corning 200 was used not only in ...
by Dale H. Cook
Thu Nov 29, 2018 5:00 am
Forum: AM Radio
Topic: AM Radio Wall
Replies: 13
Views: 647

Re: AM Radio Wall

I think I've told this one before, but right after we put a 10 kW daytimer on the air the a man in a house across the street from the transmitter site (and in the middle of the main lobe) complained of music in his basement. The water meter was at one end of the basement and the water heater and wat...
by Dale H. Cook
Thu Nov 15, 2018 12:02 pm
Forum: On-Air Studios
Topic: Dayton Receiver Manuals
Replies: 1
Views: 348

Re: Dayton Receiver Manuals

I have posted my collection of Dayton manuals at:

https://plymouthcolony.net/starcityeng/ ... tml#dayton

I would appreciate any contributions, especially raw image scans, to expand that collection.
by Dale H. Cook
Fri Nov 09, 2018 6:43 am
Forum: AM Radio
Topic: ATU rebuild
Replies: 21
Views: 839

Re: ATU rebuild

Deep Thought wrote:
Thu Nov 08, 2018 8:24 pm
... I can model it and get pretty close to the right phase shift for optimum bandwidth without having to do a full sweep.
Deep has significantly better software tools than the rest of us. I can only do that the old fashioned way, with a bridge and a Smith chart. :wink:
by Dale H. Cook
Wed Nov 07, 2018 2:58 pm
Forum: AM Radio
Topic: ATU rebuild
Replies: 21
Views: 839

Re: ATU rebuild

An OIB-1 is not going to give you an accurate tower self resistance for a tower with that high an R and X. Design to the last measured tower impedance unless you have a reason to think it has changed. If you have the last measured impedance I hope it was a full sweep, which will let you optimize th...