Search found 102 matches

by COMMENG
Fri May 04, 2018 11:40 am
Forum: AM Radio
Topic: Need Crystal for LPB-30
Replies: 1
Views: 177

Re: Need Crystal for LPB-30

Yiu might try:

http://www.af4k.com/crystals.htm (see center of Page)

and resort to a circuit shown below, or purchase a DDS kit:

Remove A3 and Feed the squarewave RF to pin 8.
by COMMENG
Thu Apr 19, 2018 12:07 am
Forum: Everything else
Topic: A bit of AM History
Replies: 4
Views: 231

A bit of AM History

My first BE job was taking care of a number of these beasts for some hometown AM Stations in OK, MO, and KS.

BTW, they sounded this good.

https://www.youtube.com/watch?v=0VYDBFDiPZY


COMMENG
by COMMENG
Tue Jan 09, 2018 10:38 am
Forum: AM Radio
Topic: What is this? A 5 kw Dummy Load or what?
Replies: 22
Views: 2762

Re: What is this? A 5 kw Dummy Load or what?

The "resistive" strip appears to have come from an older Gates BC-1T or similar vintage vacuum tube transmitter. I agree - I have a BC-1T load here and it appears identical. Bear in mind that a BC-1T load is not a 50 ohm load - it is a 51.5 ohm load. It's still a 50 ohm dummy load, in the vernacula...
by COMMENG
Mon Jan 08, 2018 10:51 am
Forum: AM Radio
Topic: What is this? A 5 kw Dummy Load or what?
Replies: 22
Views: 2762

Re: What is this? A 5 kw Dummy Load or what?

The "resistive" strip appears to have come from an older Gates BC-1T or similar vintage vacuum tube transmitter.

Each resistor is most likely rated at 412 ohms, 150 Watts or so.

The other other stuff appears to be added on to get to J0.

COMMENG
by COMMENG
Mon Dec 25, 2017 9:56 am
Forum: Everything else
Topic: Merry Christmas
Replies: 7
Views: 457

Re: Merry Christmas

Merry Christmas to all.

We had about 2" of snow here in the Central Midwest as the temp plunged to about 10F this morning. :shock:

May you have a Joyous and prosperous New Year! :D

COMMENG
by COMMENG
Thu Dec 21, 2017 12:25 pm
Forum: FM Radio
Topic: RF Spectrum Analyzer
Replies: 26
Views: 1439

Re: RF Spectrum Analyzer

Who, or what agency has "ASKED" you to do this. And just what is "second harmony"?? Fossil It is a regulatory agency within Canada, they are responsible for "Spectrum Management"; because of proximity to an airport, they are asking for more detailed scans. I'm thinking that the "2nd harmony" is ref...
by COMMENG
Wed Nov 15, 2017 11:03 am
Forum: FM Radio
Topic: FM range question - coastal mountainous terrain
Replies: 23
Views: 1513

Re: FM range question - coastal mountainous terrain

Is there some reason you can't move the transmitting facilities to the Nieves Peak area somewhere along GC 134 (such as the San Bernardo refuge) and increase power to 5kW? I concur with Deep Thought, your major problem here is obstructions from volcanic landforms with the resulting wave reflections,...
by COMMENG
Thu Nov 09, 2017 4:29 pm
Forum: From the Trenches
Topic: Your Biggest On Air Screw up..
Replies: 35
Views: 8463

Re: Your Biggest On Air Screw up..

NECRAT wrote:
Thu Nov 09, 2017 3:08 am
COMMENG wrote:
Wed Nov 08, 2017 5:41 pm
College 10 Watt FM station, St. Louis, about 19XX.
See I learned my roman numerals. That would be 1920, sir!

:mrgreen:

Ouch! :mrgreen:
by COMMENG
Wed Nov 08, 2017 5:41 pm
Forum: From the Trenches
Topic: Your Biggest On Air Screw up..
Replies: 35
Views: 8463

Re: Your Biggest On Air Screw up..

College 10 Watt FM station, St. Louis, about 19XX. I was on late at night playing some trash from a music list I despised. Earlier, my girlfriend had called and asked me if I had had a meal yet and I said no. So she said she would bring some pizza over and we could have pizza and a coke (soda pop fo...
by COMMENG
Fri Oct 20, 2017 12:23 pm
Forum: Ask the Engineers
Topic: Wanna Play "Guess What's in the Grey Box?"
Replies: 16
Views: 1318

Re: Wanna Play "Guess What's in the Grey Box?"

abwdvm wrote:
Tue Oct 17, 2017 2:13 pm
Taken at a nearby radio station. Going to be my responsibility soon.
No, but why don't you post a schematic with an explanation of the circuitry. :)
by COMMENG
Tue Oct 10, 2017 3:15 pm
Forum: AM Radio
Topic: OMNIA.7AM
Replies: 10
Views: 1812

Re: OMNIA.7AM

We ordered one for a 1kW station and are running with a loaner Omnia.7 AM right now. We are still tweaking for the sound we want. Working with the Intermediate Level tweaks right now. Lots of customization available.

BTW, has anyone read the Specifications sheets for this unit? :D

COMMENG
by COMMENG
Wed Sep 27, 2017 1:58 pm
Forum: AM Radio
Topic: DX-50 works as speaker
Replies: 9
Views: 1584

Re: DX-50 works as speaker

OK, guys, here's the skinny: The output of the variable cap connects to the tank coil ( why do they call it a "tank circuit"? ) via bolted tubing. At full power this point would arc with modulation. I noticed the bolt was literally red hot at 10 kW when I walked int the transmitter room before turn...
by COMMENG
Wed Sep 27, 2017 12:46 pm
Forum: Everything else
Topic: Parts
Replies: 0
Views: 378

Parts

I am not sure if this is the proper Forum but occasionally we see BE's needing parts for various transmitters, bot FM and AM.

A source that seems to have a large inventory of parts for older transmitters, ATU's, etc. is Dennis:

signalsradio.wordpress.com


COMMENG
by COMMENG
Tue Sep 26, 2017 1:35 pm
Forum: Everything else
Topic: FUNCTION GENERATOR
Replies: 3
Views: 460

Re: FUNCTION GENERATOR

I have a circuit that converts those low impedance unbalanced outputs to balanced ports.

Let me know if this interests you.


COMMENG