radio , tv station and radar stations still use the best single end class a amplifier - Page 2

SY · 29th August 2005, 07:26 PM

What we've developed in the radar field you won't see on your radar ever.

Frank Berry · 29th August 2005, 07:36 PM

My employer, FOX13 Television in Tampa operates the most powerful privately-owned Doppler Radar in the United States. 12.5 Gigawatts ERP.

The transmitter uses a Magnetron which is pulsed by a Hydrogen Thyratron.

Bandersnatch · 30th August 2005, 10:45 AM

That's enough for 10 flux-capacitors( and the remnant will probably support all ten of the support hardware ). When do you want to go?
cheers,
Douglas

Brian Beck · 30th August 2005, 12:20 PM

Quote:

the most powerful privately-owned Doppler Radar in the United States. 12.5 Gigawatts ERP.

I'm glad I don't live near that beast! Even in the side lobes of the antenna pattern, there are bound to be intense fields of pulsed EM energy. The oft-repeated thermal absorption argument based on duty-cycle averaging wouldn't make me feel very comfortable, when every calcium ion in every cell in my body is vibrated for a few nanoseconds every few seconds!

I guess we've slid off topic!

phase_accurate · 30th August 2005, 01:29 PM

I wonder why no one has questioned the class-A claim in the thread-title so far - after so many posts.

Transmitters are often single-ended, that's true. But most of the time they are class-C. In applications where linearity is critical push-pull class AB is used.

Regards

Charles

Brian Beck · 30th August 2005, 02:19 PM

I wouldn't take this thread’s title seriously at all. The William Johnson schematic looks like no RF amplifier I've ever seen.

But to continue with Johnson’s circuit: ARC used a variant in their MCP-33 moving coil head amp, except they drove the signal into the bottom cathode with the grid grounded. Looks like an interesting topology, although I never had a chance to hear an MCP-33. Has anyone here?

Frank Berry · 30th August 2005, 06:45 PM

"I'm glad I don't live near that beast!"

Don't worry.
The 26 foot radar dish is 250 feet in the air.
There is side lobe absorption material inside the reflector.
The beamwidth is (I believe) .1 degrees.
The radar operates at 5.75GHz with a pulse rate of 250Hz.

The radar doesn't even interfere with our 5.8GHz microwave receiving equipment which is located only 20 feet below the radar T/R dish.

29th August 2005, 07:26 PM	#11
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	What we've developed in the radar field you won't see on your radar ever. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

29th August 2005, 07:36 PM	#12
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	My employer, FOX13 Television in Tampa operates the most powerful privately-owned Doppler Radar in the United States. 12.5 Gigawatts ERP. The transmitter uses a Magnetron which is pulsed by a Hydrogen Thyratron. __________________ Frank

30th August 2005, 10:45 AM	#13
Bandersnatch diyAudio Member Join Date: Jul 2003 Location: Ann Arbor, MI	That's enough for 10 flux-capacitors( and the remnant will probably support all ten of the support hardware ). When do you want to go? cheers, Douglas __________________ the Tnuctipun will return

30th August 2005, 02:19 PM	#16
Brian Beck diyAudio Member Join Date: Dec 2004 Location: South Florida, USA	Title is non-sense I wouldn't take this thread’s title seriously at all. The William Johnson schematic looks like no RF amplifier I've ever seen. But to continue with Johnson’s circuit: ARC used a variant in their MCP-33 moving coil head amp, except they drove the signal into the bottom cathode with the grid grounded. Looks like an interesting topology, although I never had a chance to hear an MCP-33. Has anyone here? __________________ Brian

30th August 2005, 06:45 PM	#17
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	"I'm glad I don't live near that beast!" Don't worry. The 26 foot radar dish is 250 feet in the air. There is side lobe absorption material inside the reflector. The beamwidth is (I believe) .1 degrees. The radar operates at 5.75GHz with a pulse rate of 250Hz. The radar doesn't even interfere with our 5.8GHz microwave receiving equipment which is located only 20 feet below the radar T/R dish. __________________ Frank

30th August 2005, 01:29 PM	#15
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	I wonder why no one has questioned the class-A claim in the thread-title so far - after so many posts. Transmitters are often single-ended, that's true. But most of the time they are class-C. In applications where linearity is critical push-pull class AB is used. Regards Charles

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