HRWB 213 - Radio Rejuvenation Projects with Dan Quigley, N7HQ

SHOW NOTES
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​Dan’s Github - Super Simple Keyer
https://github.com/mgi2212/simple_keyer

SWR Chart
https://4.bp.blogspot.com/-y_qffpew5yI/Ti38UfgrmDI/AAAAAAAAACg/AVgwVEwL8Yc/s1600/Rasmsey.png 

Return loss explained
https://www.everythingrf.com/community/what-is-return-loss 

From Dan:

I really borked up the explanation of Return Loss and wanted to correct that here in the notes. There is a much better analogy:

Imagine you are standing in front of a mirror, holding a flashlight. The light beam represents the RF signal being sent down a transmission line to an antenna. 

• Perfect Match (No Return Loss): If there is no mirror (or the mirror is perfectly transparent), all the light from the flashlight passes through without reflecting back. This is like having a perfectly matched impedance where all the RF power is transmitted to the load without any reflection. In this case, the return loss is very high (ideally infinite), meaning there is no power reflected back.
  
  
  
• Partial Match (Some Return Loss): If the mirror is partially transparent, some of the light passes through while some is reflected back towards you. This represents a scenario where there is some impedance mismatch. Part of the RF power is transmitted to the load, and part of it is reflected back. The amount of reflected power indicates the return loss. The less the light reflects back, the higher the return loss, indicating a better match.
  
  
  
• Poor Match (High Return Loss): If the mirror is almost completely reflective, most of the light bounces back towards you. This is akin to a significant impedance mismatch where most of the RF power is reflected back. The return loss is low in this case because a large proportion of the power is not being efficiently transmitted to the load.

Remember though, the actual value is expressed in dB and is the difference between the power leaving the transmitter and that reflected back from the antenna. So an RL value of 1dB would represent a difference of 1dB between the measured power being reflected back and the power being transmitted. That is (counter-intuitively termed a high return loss)  A RL value of 20dB would represent a 20dB difference between the power being transmitted and the reflected power or a low return loss.

Make sense?

N7KOM Microlight Traps
https://www.etsy.com/listing/1595257587/microlight-qrp-hf-trap-kit-v3-for-use

Spark Plug Gear EFHW Transformer
https://www.sparkpluggear.com/shop/p/sparkplug 

Goal Zero Skylight
https://goalzero.com/products/skylight-portable-area-light 
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Labjack data acquisition
https://labjack.com/ 

Test Equipment:

• A GOOD VOM/VTVM - the kind with a needle not an LCD display 
• Oscilloscope 
• A GOOD set of hand tools
• Can of DeOxit
• LCR Meter
• Signal Generator
• Frequency Counter
• Spectrum Analyzer
• RF Power Meter
• Dummy Load
• SWR Meter
• Variac (Variable Transformer)
• Audio Signal Tracer
• (De)Soldering Station
• Desoldering Tools (ask your dentist)
• Magnifying Lamp AND Microscope
• Logic Analyzer
• Heat Gun: For heat shrink tubing and desoldering components.
• High-Voltage Probe
• Alignment Tools