HF amplifier purchase

Mikek

I doubt there is a 50ohms resistor in the output. It's ususally a hard-driving direct push-pull stage and a measurement bridge. This bridge causes power to be curbed if you are trying to do things such as driving into a short at high power.

The manual is a bit hokey, they refer to transistors without providing the schematic.

A great web site would be ic-bugs.com.

Indeed, the situation is getting messy with pure inductance, since the inductive reactance would be very low at low frequencies and when driven with a constant voltage, the current would be large. The required power would be very large at low frequencies, unless the inductive reactance could be tuned out with a series capacitive reactance, but this would require switching capacitors over the frequency range.

In reality, the coil is most likely not a pure inductance, but in reality it has some series resistance as copper losses (for DC) and skin losses (proportional to square root of frequency) in addition to the frequency depended inductive reactance. The coil resistive components (or the RL time constant) should be known before deciding what power amplifier should be selected.

There is 50ohms, you can see it on page 130 of the repair manual PDF:

Actually 4 parallel 100 ohms, with 4 more in series

Cheers

Klaus

I have ordered it from Digikey, Lasse, thanks for the pointer

A whopping 112 USD, glad it is no me that is paying :-)

ent=333

Since it was designed to drive 50 Ohm loads, it has to be a 50 Ohm source. If it wasn't, it would be useless to test filter circuits designed for 50 o hms. That is not the same as a HF Amplifier. The amplifier would waste 50% of its output power into a design like that. You need a design that transfe rs maximum power into your 50 Ohm load. Impedance matching is more importan t in receiver designs, where you sometimes use a 3dB pad to improve the imp edance matching around a mixer circuit. You lose 3dB system gain, but you i mprove the overall signal quality.

Yes, but that is a function generator, not the big EMC amp. For 40Vpp over the required frequency range into a possibly iffy load you need something big.

That's the EVB. The chip is

Why is the DK Farnell board so different then the Mouser Board?

Get it while you can, 1 in stock.

Mikek

Mouser says: Images are for reference only See Product Specifications

Am 04.03.2020 um 00:42 schrieb Klaus Kragelund: