Chelsea Practical Technical Applications


Double-Fusing for an Automotive Mobile Installation

When installing a direct battery connection for a mobile rig, should you splice in a fuse for both plus and minus wires at the vehicle’s battery? The answer may surprise you. When it comes to grounding configurations, amateurs, more than anybody else, should recognize the possibilities of electron flow through paths that we never imagined. Only a dummy would put a fuse in a grounded return wire. Right? You can call them dummies all you want as you look at your burned-out wreck in the junkyard.



Coax Cables RG-214 Compared to RG-213

RG-214 costs about $8/ft at the time of this writing. That’s a hard pill to swallow when you are on a consumer’s budget. But then you look at RG-213 which (at the time of this writing) is priced at a little bit more than $1/ft. RG-214 looks and feels like RG-213, but has more loss per 100 feet than RG-213. But wait a minute… RG-214 has very expensive silver plating on both its center conductor and both shields but STILL has more loss than RG-213!

Is somebody kooky here or something? Maybe somebody is trying to take us to the cleaners. Read about why RG-214 is absolutely CRITICAL in some applications and the theory behind why.


HT Rubber Duck Antannae Evaluation

In this web page, we will learn how to evaluate your HT rubber duck antenna’s performance and compare it with aftermarket HT antenna performance. We will also look at a YouTube video where the author made a very common mistake and then drew unfounded conclusions on his observations.

Here’s the thing, folks…A rubber duck antenna is not an antenna until it is married to the HT it was designed to work with. Look at the illustration on the right. Where is the counterpoise? This thing, as is, will only work at all at the fundamental by the grace of God. At 70 cm however (its harmonic), it will work as an end-fed verticle. But so configured, it will have a high impedance in. It will therefore work fine on 70 cm if fed with a high impedance such as is easily possible with the HT it is married to.


The De-mystification of dBm and dB for the Masses

Have you felt perplexed when you see the specifications of dB and dBm? Maybe you were wondering what dB was all about in the first place. In this web page, we address the decibel from a practical perspective dumping the hype and hyperbole. It is a down-to-earth discussion of these things.


Sometimes it seems like it takes a brain to decipher transceiver technical specifications. While those new to amateur radio will unquestionably be intimidated, be assured that it is not true. What it does take, however, is a little knowledge.


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