Search found 459 matches

by kcbooboo
Tue Feb 13, 2018 7:35 am
Forum: STL Engineering
Topic: Marti 950 MHz STL-10 spurious emissions
Replies: 6
Views: 1441

Re: Marti 950 MHz STL-10 spurious emissions

The unit was on my bench over 3 years ago. It's either back in service working fine or sitting on a shelf until something else breaks and it gets put into service. I'm not losing sleep over a few dB which will probably be attenuated by the antenna system. "These aren't the 'droids we're looking for....
by kcbooboo
Mon Feb 12, 2018 5:30 am
Forum: AM Radio
Topic: Audio Bandwidth of an AM Broadcast Station
Replies: 9
Views: 462

Re: Audio Bandwidth of an AM Broadcast Station

It's interesting that there's so little energy in the 0-5 kHz range yet so much more in the 5-10 kHz range. Also, the modulation level seems to be quite low. I wonder what sort of program material was being tranmitted at the time you caught that trace. ClearChannel / iHeartRadio stations seem to hav...
by kcbooboo
Tue Jan 16, 2018 6:41 am
Forum: STL Engineering
Topic: Marti 950 MHz STL-10 spurious emissions
Replies: 6
Views: 1441

Re: Marti 950 MHz STL-10 spurious emissions

I feel reasonably confident that with the 50dB of attenuation ahead of the SA, the harmonics I was seeing are truly present. When I increased the input signal by removing some attenuation, the fundamental and all harmonics increased by exactly the same amount. Usually SA overload or internally-gener...
by kcbooboo
Tue Jan 16, 2018 6:31 am
Forum: FM Radio
Topic: Repair Log: BE FXi-60
Replies: 3
Views: 351

Re: Repair Log: BE FXi-60

The snubber diode in a switching PS does almost as much work as the driver transistor. There's a lot of peaky inductive energy sent into it. Those two parts are getting quite a workout. They just might have gotten tired. It happens. Be glad you got 10 fault-free years.

Good repair, though.

Bob M.
by kcbooboo
Sun Dec 31, 2017 7:26 am
Forum: FM Radio
Topic: Wanted reliable monitor amp
Replies: 11
Views: 477

Re: Wanted reliable monitor amp

The Crown D-75 or D-75A amps can be found cheap. Once you replace the two 10V zeners that short out, the two 820 or 910 ohm 2w resistors that then burn up and damage the board, the NE-2H power lamp that dies (causing that "doesn't power up" syndrome), and a couple of electrolytic caps on the main bo...
by kcbooboo
Tue Dec 12, 2017 7:10 am
Forum: FM Radio
Topic: BE FM 25T Wandering Readings
Replies: 4
Views: 318

Re: BE FM 25T Wandering Readings

It doesn't take much RF floating around to upset the analog readings. I have a site with a 1kw AM TX in the adjacent rack and the tower about 50 ft away, and EVERY analog input has a 10uF 25V electrolytic cap across its screw terminals. That at least made the readings usable. A divider/filter as rec...
by kcbooboo
Sun Nov 19, 2017 4:13 am
Forum: STL Engineering
Topic: Women Hearing Distorsion on Station After STL realign
Replies: 20
Views: 1074

Re: Women Hearing Distorsion on Station After STL realign

Imagine if iPhones had CRTs. People wouldn't be able to text and drive, text and walk, or text while doing anything else. What a world! Battery life would be specified in minutes. No more cracked faceplates from putting the phone into your back pocket and sitting down.

Bob M.
by kcbooboo
Tue Oct 31, 2017 5:20 am
Forum: Radio Studio Engineering
Topic: Arrakis 12,000 series console issues
Replies: 7
Views: 420

Re: Arrakis 12,000 series console issues

I don't know if your console has this, but I've seen some that use Molex connectors that have an "effects loop" on every input that must be jumpered if there is no external processor or other gizmo. If all the wires were just cut off, there could be some that just need to be connected together on so...
by kcbooboo
Wed Oct 25, 2017 1:31 pm
Forum: FM Radio
Topic: Nautel NV20 repair/restoration
Replies: 19
Views: 2079

Re: Nautel NV20 repair/restoration

Wouldn't it be nice if a B-I-G company like Nautel could acquire the schematic for these power supplies, so they COULD be repaired in the field. Probably would have made the repair job a whole lot easier and faster.

Bob M.
by kcbooboo
Thu Sep 28, 2017 6:41 am
Forum: FM Radio
Topic: V & H antenna radiated power
Replies: 3
Views: 432

Re: V & H antenna radiated power

Thanks for the replies. Sorry, I have to admit to being an old wife, or at least knowing one (and yes, I have stayed at a Holiday Inn more than once).

Bob M.
by kcbooboo
Wed Sep 27, 2017 1:18 pm
Forum: FM Radio
Topic: V & H antenna radiated power
Replies: 3
Views: 432

V & H antenna radiated power

Let's say a translator is licensed for 200 watts ERP into a directional yagi antenna with 6dB gain and this antenna is horizontally oriented, so TPO is about 50 watts (assume no loss in the coax). If they connect a second 6dB gain yagi through an appropriate power splitter and orient it vertically a...
by kcbooboo
Thu Jul 27, 2017 10:32 am
Forum: Ask the Engineers
Topic: A real head-scratcher
Replies: 7
Views: 1112

Re: A real head-scratcher

There is joy in Mudville today. I purchased a Sencore CR70 CRT tester/rejuvenator for $65 shipped. It looks brand new. Came with all the adapters, including the "universal adapter" (a pod with EZ-clips at the end of five wires) and has the setup book. It passed the field tests. I subsequently bought...
by kcbooboo
Mon Jul 24, 2017 6:47 am
Forum: Everything else
Topic: Mounting stuff to old concrete block wall?
Replies: 18
Views: 1843

Re: Mounting stuff to old concrete block wall?

Since I mounted my dryer outlet on wood nailed to the poured concrete wall, here's another funny. When I bought my house in 1987, it came with a washer and dryer (still in service today and working great; the quality went in before the GE nameplate went on). There was a separate circuit run for the ...
by kcbooboo
Tue Jul 18, 2017 5:44 am
Forum: AM Radio
Topic: Antennas for Field Measurement
Replies: 7
Views: 1075

Re: Antennas for Field Measurement

I believe Kevin was referring to the previous or original proof-of-performance measurements that had to be done when the station went on the air. Those are your reference, and the signal levels were surely made with an FIM. I have an FIM and a spectrum analyze and Scott loop antenna. There is a cali...
by kcbooboo
Mon Jul 17, 2017 4:34 am
Forum: Everything else
Topic: Mounting stuff to old concrete block wall?
Replies: 18
Views: 1843

Re: Mounting stuff to old concrete block wall?

I did a similar thing but to a poured concrete wall. Rather than fight with the drill bit moving around, I used a Hilti nail gun to anchor a piece of 3/4 inch plywood to the wall. I could then mount the dryer outlet to the plywood with ordinary wood screws. Another way that might work is to use your...