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Author Topic: 3kw pep solid state amp 1.8-54 mhz  (Read 844 times)

Offline digitalmod

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3kw pep solid state amp 1.8-54 mhz
« on: February 12, 2018, 0154 UTC »
 :D  When I was a boy I WAS IGNORANT in many ways, but could make an AM transmitter and in fact almost killed myself a number of times, HV KILLS.
But, here is a solid state 3 kw pep amp, which would need cooling fan, but with some amount of carrier in 41 meter band, and we would also need harmonic filter would make a 700 watt am transmitter. You figure which class D amp you want to series modulate or use the Heising method? Did I spell that right.
Its work for a technical person in a lab to complete the unit. Now, question was asked about class C vs E vs bipolar vs FETS.
I can't quite price everything here, but 3 kw pep would make a lethal rig driven with a ssb exciter.
Oh, naughty.. but there are many ways to make a transmitter work.. its a matter of choice, your needs, your skill level and pocket book. My gut feeling here is home brewing a kw am transmitter with class E, would be by far least expensive, but its also needs higher skill levels and lab equipment to adjust.

https://www.ebay.com/itm/3000-Watt-PEP-LDMOS-RF-Power-Amplifier-1-8-54-MHz-HF/222707564979?hash=item33da67c1b3:g:wjQAAOSwNNdZ1ToL
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Offline Stretchyman

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #1 on: February 12, 2018, 0737 UTC »
Some BS there, they'll push close to a KW each so will barely do 2KW for a pair.

They are however the device of choice.

As previously discussed low level A.M. and further amplification wont sound as good as High level mod.

Str.

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Offline digitalmod

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #2 on: February 12, 2018, 1728 UTC »
 8)  Yes, still amazing solid state gear if you have the skill to complete it and the power supply, plus a driver. Not sure how much drive. Generally a fan helps the sink get that time down for broadcasting service :'(
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Offline JimIO

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #3 on: February 12, 2018, 1749 UTC »
I don't think too many pirates would be interested in something that needs more than a (four words "Made in the USA") NEMA 5-15P to IEC C13 power cord. ;D

Offline digitalmod

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #4 on: February 12, 2018, 1841 UTC »
 :o Its funny I saw a discussion of a pirate radio that was FCC part 15 approved. When I was a kid, the FCC allowed 100 milliwaatt walkie talkies, my brothers had a set and I could hear them maybe half mile out. Later FCC with demands from corporate broadcasters changed it to millivolts at very close distance to antenna. That says a part 15 transmitter will be lucky to be receivable across the street !
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Offline redhat

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #5 on: February 12, 2018, 1857 UTC »
I don't think too many pirates would be interested in something that needs more than a (four words "Made in the USA") NEMA 5-15P to IEC C13 power cord. ;D

Speak for yourself.  Someday I'll need a range outlet to power my solid state TX :)

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Offline JimIO

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #6 on: February 12, 2018, 1924 UTC »
I heard a guy on the 75M AM window saying he did that. 2 Cree SIC FETS, no power transformer. Just full wave rectify 220 with 2 diodes. Said he had a web page and gave his call but I never found it.

Offline Azimuth Coordinator

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #7 on: February 12, 2018, 2224 UTC »
Quote
As previously discussed low level A.M. and further amplification wont sound as good as High level mod.

Depends on how your low level modulation is generated..

AC
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Offline JimIO

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #8 on: February 12, 2018, 2355 UTC »
Speaking of... Does anyone know how "compatible side band" (CHU time) is generated?
I have looked and can't find it explained anywhere. I'm guessing it starts out as low level AM and then one side band and some of the carrier if filtered out then it is linear amplified.
 

Offline redhat

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #9 on: February 13, 2018, 0028 UTC »
Most likely the Kahn method with carrier leak.

+-RH
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Offline Pigmeat

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #10 on: February 13, 2018, 1948 UTC »
I don't think too many pirates would be interested in something that needs more than a (four words "Made in the USA") NEMA 5-15P to IEC C13 power cord. ;D

Speak for yourself.  Someday I'll need a range outlet to power my solid state TX :)

+-RH

C'mon over. I've got one in the kitchen I don't use and another in the basement that I can't figure out what it's for? The one for the dryer is on the the other side of the basement. Maybe they cooked down there in the pre-air conditioning era? This is an old house, built well before the lightbulb and possibly fire.

Offline TheRelayStation

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #11 on: June 27, 2018, 0545 UTC »
As previously discussed low level A.M. and further amplification wont sound as good as High level mod.
that is not always true.
low level AM can be just as good and sometimes better than high level AM.
it depends on how you balance the carrier level to low level AM.
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Offline redhat

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #12 on: June 27, 2018, 1546 UTC »
As your carrier power levels increase, low level AM makes less and less sense if for no other reason than power consumption.  High level AM with PWM has been the broadcast standard for anything over 100 watts for the last 40+ years, and if carefully designed will be indistinguishable from low level modulation.  40% efficient vs. 85%?  Thats a no brainer to me, especially if I have to pay for the power or the generator...

+-RH
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Offline Josh

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #13 on: June 27, 2018, 1553 UTC »
Still waiting on the release of Boba FETs to build that killer amp.

Offline TheRelayStation

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Re: 3kw pep solid state amp 1.8-54 mhz
« Reply #14 on: June 27, 2018, 1913 UTC »
As your carrier power levels increase, low level AM makes less and less sense if for no other reason than power consumption.  High level AM with PWM has been the broadcast standard for anything over 100 watts for the last 40+ years, and if carefully designed will be indistinguishable from low level modulation.  40% efficient vs. 85%?  Thats a no brainer to me, especially if I have to pay for the power or the generator...

+-RH
i agree but if configured correctly, low level can be efficient and perform with excellent results.
since the entire scheme is linear from the start to the final amplifier, its just a matter of leaving a generous amount of carrier "headroom" for the AM PEP.
its just a balancing act between the two.
i realize with low level, i am not able to utilize the full power output since its linear, only about half the power output of what would be capable at high level but the produced power output from the current linear setup is more than enough for what i do and its better for the amplifier and my electric bill anyway.

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