looking for high current (>4A), low output (<50 Ohms) impedance amplifier

[ptdspp]

Hi everyone, I'm looking for recommendations for a high-current (>4A), low output impedance (<50 Ohms; but preferably as close to 0 Ohms as possible) amplifier working from 30MHz to, roughly, 1MHz (the lower the better). Since the amp needs to work in the AM range, and this forum has a lot of technical experts, I thought someone might have been exposed to such an amplifier, or could tell me how to modify a commercially available amp (rip out the matching transformer network, for example).

My mostly-capacitive load is 1 Ohm to 0.001 Ohm range, depending on frequency (10KHz to 30MHz), and I'd like to get 10mVpp across it at any particular frequency. Need a sinewave or any other waveform containing a strong fundamental frequency (can live with ugly harmonics, just need strong fundamental present to view on spectrum analyzer; sinewave is ideal of course).

My online searching has found some close-misses:

1. Exactly what I need for below ~1MHz (output impedance 0 Ohms, can drive short circuit without harming itself), but looking for something else for above 1MHz:
http://www.rf-pwr-amps.com/Product%20Imformation.html

2. This one is great, it can drive a short circuit without harming itself, but high (50 Ohms) output impedance limits current to ~4A in this price range ($14K USD), and higher current units are much more expensive:
http://www.amplifiers.com/html/18200.asp?id=9

3. This one has 1 Ohm output impedance, but current is limited to 2A, and bandwidth is only 5MHz.
http://flcelectronics.com/f30pv.html

Any recommendations for what can be done is much appreciated. Also, does anyone have experience with cables that can carry high current (10App, ~200mVpp max) to the load? Distance can be made short (< two feet or even less) to avoid transmission-line effects of 50 Ohm cables (can ignore T-line if distance < one-tenth of wavelength, I assume).

Thanks in advance

[DMOD]

And what is the application?

Phil - AC0OB

[WA1GFZ]

How much voltage swing do you need?
Transmission line will not be easy at that Z. #12 or #14 mil single shielded Teflon wire has a Z around 10 ohms. You could parallel a number of them to get the Z lower. At least 10 of them would be flexable.  If you want to buy something commerical check Amplifier Research, IFI and there are a couple others out there who make BB amps for EMI testing. Sounds to me you want a source follower as an output device with a well protected power source. I think it is doable. There are newer FETs out there that wil generate a lot of power but not cheap. The typical class e stuff doesn't work out to 30 MHz unless you find a FET that can operate efficiently.