Re: H4 F303 artwork updates(4.2 -> 4.2.1) #nanovna-h4 #circuit #improvement
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ASSUMING the SA602 inputs are 1.5K each for a total of 3K my calculations come up with changing the 11 ohm 1% resistor with a 13.2 ohm 1% resistor from Digi-Key...??
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1 over 1/3000 + 1/91 + 1/115.2 = 49.992 ohms Only one part needs to be changed vs swapping out all 4... The 4.2.1 ckt math would be: 1 over?1/3000 + 1/56 + 1/529.9 = 49.806 ohms 73 Dallas, KD4HNX Whatever you do, don¡¯t fall victim to?¡°paralysis by analysis.¡± Go ahead and buy/build one and start? tinkering with it. This is a learn by doing hobby. No politician or scholar assured your freedoms. A Soldier, Sailor, Marine, or Airman did! On Thursday, March 26, 2020, 07:58:21 AM EDT, erik@... <erik@...> wrote:
4.2.1 is better because the input impedance of the SA602 (1.5kOhm//3pF per input) has less impact compared to 4.2 -- NanoVNA Wiki: /g/nanovna-users/wiki/home NanoVNA Files: /g/nanovna-users/files Erik, PD0EK |
Dallas N4DDM