On Sun, 23 May 2004 20:42:59 GMT, "Lord Snooty" wrote:


The amp is single-ended out of an MRF136, so I presume it's Class A. The amp's
designation is H-10 (I bought it surplus). It's rated at around 15W, 0.1 - 30
MHz. The circuit diagram shows no hint of current limiting circuitry.

If one is serious about proper design of a matching network - a network, I
might add, which attaches *directly* (near as dammit) to the Tx output - then
one is all at sea without a proper knowledge of source impedance. See my
comments in the other thread about this.

Hi Andrew.

Specification sheets respond to these issues quite well. The MRF136
is a 400MHz device, normally offering 15W max with about 16dB gain at
28Vdc (although rated higher) in a class A configuration (showing
about 60% efficiency).

As would be expected, it covers a lot of turf. In the HF, the output
Z runs easily near 50 Ohms in push-pull circuit configurations;
otherwise it is simpler to describe it in the teens to tens of Ohms
across any number of variables you do not disclose (like frequency,
the actual configuration, additional interface components). 1 - 10
MHz does not bode well towards the best implementation of an UHF
device.

Load pulling is vastly simpler than S-parameters (also specified in
the data sheets for this device, down to 1MHz), why you want to marry
the two is a mystery.

73's
Richard Clark, KB7QHC