As noted, first test was at -40 dBm. I raised the level just now
to max, -17 dBm--very little change from before--the output
impedance decreased about 0.03 ohms for each frequency.
Steve
On 9/16/2022 8:55 PM, Tom Lee wrote:
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Those numbers have a believable trend, but the magnitudes seem too
high. I don't know what the parasitic emitter resistance is of a
2N5109, but I would be surprised if it were bigger than an ohm.
The output capacitor's ESR adds to that, of course, but a good cap
shouldn't have several ohms of ESR. So, if you include realistic
parasitics, the output resistance should be an ohm or less. The
milliohms number I gave earlier is the ideal value you would get
in the limit of no parasitics.
How large an excitation are you using to probe the output Z?
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 9/16/2022 19:48, Steve Ratzlaff
wrote:
I breadboarded the circuit just now using 2N5109's and swept
the output Z with the DG8SAQ VNWA, 10 kHz-30 MHz. The circuit
draws 117 mA; the output transistor draws 84 mA. The output
impedance is mostly flat, gradually rising after about 10 MHz.
50 kHz 4.23 ohms
1 MHz 4.42 ohms
10 MHz 5.27 ohms
20 MHz 6.80 ohms
30 MHz 8.77 ohms
Steve AA7U
On 9/16/2022 5:44 PM, Mikek wrote:
Someone sent me a private messaged and corrected me on the
output impedance of the 50 to 1 transformer,
it is 0.001¦¸ or 1 milli¦¸. So, impedance ratio of 2500 x -.001
= 2.5¦¸ primary impedance. I'm not sure I know how to figure
the output impedance of the
power amp in the HP4342A, I would have thought 220¦¸.
I'm posting the schematic of the impedance converter the
drives the injection transformer primary and asking,
What is the output impedance of the impedance converter?
????????????????? Thanks, Mikek
