Checking my math
¿ªÔÆÌåÓýIt all looks right except your maximum power from the Hermes is 72 mW so that would be your reference.? What if you wanted to use the amp with your Hermes on 40M?? [72 mW ¨C 1 mW] is [17.5 dBm ¨C 0 dBm]¡ so 17.5 dBm pad.? Now calculate your resistors¡? That way it still works for 10M too. ? ? Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of David Dill via groups.io
Sent: Monday, May 19, 2025 5:26 PM To: [email protected] Subject: [AmateurRadioBuilders] Checking my math ? Hi all ? I have just completed my first 20 amp build.? This is my first foray into surface mount soldering and I think all has gone well. Really cool stuff. ? I am building this amp to accompany a Hermes Lite to turn it into a full 15w blowtorch. The Hermes has an "RF Out" that bypasses the internal 5 Watt PA. ? I have measured that output on all bands. It ranges from 72mws on 10 meters Down to 42mw on 40 meters. ? My hunch is to calculate the Pi Attenuator for 41 mw.? Is that a good bet? ? Here are my numbers - check me out and let me know what will be best.?? I failed Algebra 2 in High School. ? ?To attenuate 42 mw to 1mw, I need to attenuate 41mw or 16.12 db ? The values I come up with are 68.5276 156.026 68.5276 ? So real values 68 160 68 ? Does this look right to you guys ? What would you all suggest? ? Thanks again for this great group. Looking forward to building the T41 ! ? 72 David W0NP ? |
K9HZ