Looking at the language, I would say it is a compromise at best and probably more tuned to CB.

It could also be that the subwoofer's amplifier circuitry is a Class D (switch mode)topology whose output is not well filtered or it's filtering has been compromsed.

Martin, glad to see you are a Homebrewer.

Since I can't seem to upload pdf files or schematics, here is the next best thing:

http://www.clarisonus.com/Archives/TubeTheory/ClassC.pdf

Look at page 3, right side for the waveforms.

Consider a Class C broadcast transmitter transmitting on 1 MhZ. The input waveform to the grid, an RF sine wave, will have a total period of 1 microseconds. The positive portion of the grid waveform will be going from zero voltage to maximum voltage back down to zero voltage in 500 nanoseconds.

1. The grid drive will be a sine wave of 200 Volts Peak-to-Peak and we are only interested in the positive portion or the 100 volt positive segment

2. (From bottom to top) the DC grid bias supply is set to -90 volts, which is connected to a 10K resistor which is connected to a 2.5 mH choke and then to the grid,

3. Plate voltage will be 3000 Volts with a maximum current of 0.5 Amps

4. The grid voltage rises from zero to +10 volts at the 50 nanosecond time click, grid and plate current starts to flow, but not much

5. At 100 nanoseconds the grid voltage is at 58 volts and plate current is significant

6. At 250 nanoseconds, the grid voltage is 100 volts maximum and the plate current is maximum, input power at this time is 1,500 Watts

7. From 255 nanoseconds on, the grid voltage starts to fall, the plate current starts to fall

8. At 450 nanoseconds, the grid voltage starts to fall below + 10 Volts and the plate and grid current tends toward zero,

9. At 500 nanoseconds the grid voltage finally goes to zero, plate current is zero


So the time between about 100 nanoseconds and 400 nanoseconds is where the majority of energy is dumped into the resonant circuit, usually a Pi-Network or Pi-L network circuit which not only stores energy, but provides an impedance match between the tube plate and the output circuit.

I hope this helps

Phil – AC0OB

The OP is trying to understand basic C class theory so discussion of other classes of operation should be relegated to a later thread.


A tube is biased below cutoff so that only a short time period of the driving signal triggers the tube to conduct. So if we're feeding the grid of a class C tube biased negative below cutoff, we only allow a small positive portion of that driving sine wave to force the tube to conduct for a short period of time.

Phil - AC0OB

You have to take the amplifying device into consideration.

In class A, the device is dissipating about 70% of the input power over the full 360 degree conduction cycle.

In class B, the device is dissipating about 50% of the input power over the 180 degree conduction cycle.

In class C, the device is dissipating about 25% of the input power over the 90 degree conduction cycle.

The shorter the time the amplifying device is conducting, the more power that is available to the output circuit, because the amplifying device is wasting less power during this shorter time. Hence, the output power to input power efficiency rises.

In class C, the energy during that shorter time period is being pumped into the LC cicruit, in this case, a resonant circuit which recreates the full sine wave.

It says it has certs:

http://solarenergy.advanced-energy.com/en/PVP4800.html

Most of these inverters are two-stage bridge type inverters with Sine Wave output and fully filtered.

It sounds to me like the inverters input or output filtering went bad.

Have the homeowner contact AE and let them know of the interference.

Addendum: Did the installers properly ground Mr. Screamer?

Phil - AC0OB

If you can't find anything publicly, you might want to think about a homebrew exciter feeding a linear.

Ken has a linear 160m monobander here:

http://w2dtc.com/3cx3000f7.htm

Phil - AC0OB

A piece of bandsplattering piece of junk. I would stay away from it.

Save up your money and buy a decent amp.

According to the schematic, the original design used a total of 40.6 ufd of capacitance.

If you can find 330 or better yet, 470 uF@450 electrolytics you would have better filtering and less sag on transmit.  


This kit from Harbach would give you only 25.65 uFd of capacitance which is only about 64% of original design capacitance. Make sure the kit is for a voltage doubler circuit and not a Full Wave Bridge.

Phil - AC0OB

Check ot this discussion as well:

http://amfone.net/Amforum/index.php?topic=29720.25

Phil - AC0OB

Is the sound that of a big thump or a snap?

If it is a big thump check the soft start relay/circuit and make sure the Soft Start relay contacts are not welded.

Phil - AC0OB

This is where you make an offer 10 minutes before the close of the Hamfest.

Sometimes negotiations have to be done. If the seller doesn't acept your offer, you keep your money and he has to haul the stuff home.

Phil - AC0OB

Take a look at the inrush protection/limiters here.

For 240V, the relay is a 240VAC coil across the 240V line with a single 20ohm 10W resistor.


http://www.ameritron.com/pdffiles/ICP-240.pdf

Phil - AC0OB

Not that I am aware of.

Now, what you can do is go to some of the earlier ARRL publications, such as QEX or their Amplifiers publications, 73's Magazine, or the Internet, and build your own Amp from collected parts.

You can find parts and tubes from AES

http://www.tubesandmore.com/ and http://www.esrcvacuumtubes.com/ and

http://www.rfparts.com/ or MFJ or by attending Hamfests, especially parusing the tailgaters.

As far as PCB's,  FAR Circuits  http://www.farcircuits.net/  has a lot circuit boards for various projects.

And oh yes, go to he Homebrew and Boatanchor sections of various ham related web sites such as
http://www.eham.net/ehamforum/smf/index.php/board,16.0.html and

http://forums.qrz.com/forumdisplay.php?32-Homebrew-and-Kit-Projects


Phil - AC0OB

See Pages 23 and 51 of the manual.

Phil - AC0OB