Tag Archives: K9ZW Learned

About RadioReference.com

Picking up where published guides once covered, and where formerly easy to access web databases once ruled, RadioReference.com is whole lot of information cleanly put together online.

RadioReference.com

RadioReference.com is the world’s largest radio communications data provider, featuring a complete frequency database, trunked radio system information, and FCC license data. RadioReference is also the largest broadcaster of public safety live audio communications feeds, hosting thousands of live audio broadcasts of Police, Fire, EMS, Railroad, and aircraft communications.

With hundreds of thousands of members, RadioReference is a world leading collaboration platform for public safety communications professionals and hobbyists.

via RadioReference.com.

As a heads-up the Mobile version http://m.radioreference.com is hand and shows very cleanly on my phone, though it is a limited portion of the whole website.

73

Steve
K9ZW

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The Trouble with Toroids – Getting all Wound Up Apparently About Nothing…

When you run across a well done article on a topic we all tend to need every bit of help on, well you share the link to that excellent bit of work.

I’ve had more trouble with winding toroids than any other aspect of kit building, excepting fussing with surface mounted components too small to see without a glass.

Mike VE3WDM has done an excellent write-up of how he conquered the toroid problem, with very helpful onwards links.

“VE3WDM’s HAM RADIO BLOG: Are toroids getting you all wound up” at:

http://ve3wdm.blogspot.com/2010/10/are-toroids-getting-you-all-wound-up.html

Hope you find this useful!

73

Steve
K9ZW

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50 Ohm Impedance Matching – Mystical, Magic, or Codswollup?

50 Ohm Impedance Matching –  is it something Mystical, the Magic solution to all feedline woes, or simply a bunch of Codswollup?

Perhaps it is a bit of all of these!

The average Radio Amateur’s gear is all nominally rated to use 50 Ohm coax feedline, matched to a 50 ohm feed point on an antenna.

What is meant by 50 Ohm?  

First it is NOT about resistance at all, but rather 50 Ohm IMPEDANCE.

What is this beast “Impedance” and how is it different than “Resistance.”

We have pretty good analogies for Resistance, how it is descriptive of how a material slows down the flow of current. Sort of like the lightbulb in our flashlights resisting the flow of the battery current to the point the wire itself glows with light!

“Resistance is a concept used for DC (direct currents) whereas impedance is the AC (alternating current) equivalent.”

Lets consult some well written resources:

Emrcorp techinfo on Impedance – see the link “The Fifty Ohm Enigma” PDF download

Cable Impedance at Epanorama

http://www.physlink.com/education/AskExperts/ae517.cfm

http://wiki.answers.com/Q/What_is_the_difference_between_electrical_resistance_and_impedance

A study of these, and ARRL Radio Amateur Handbook information, shows that 50 Ohm Impedance Matching is a touch more complex than it would seem at first, with various situations being important and in others not an issue.

I’ve seen field day exercises where apparent mismatches were “leveled out” using military style improvised techniques and I have seen the improvement in signal both received and transmitted from careful matching.

Hope these resources cast some light on what at first seems an arcane subject area!

73

Steve

K9ZW

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Crank Up Tower Perils – What Goes Up WILL Come Down….

Recently inspected another part collapsed crank-up tower – in this case one of the slave cables had broken, allowing the upper two sections to fall until tower hardware caught them.

Was also discussing with local club members another collapsible tower with a “safety” who’s safety-disconnect pull rope had fallen off.

On the inspection I made I was able to use a Manlift, to greatly reduce personal risk of exposure if the tower  further telescoped suddenly.  I was at great pains to position the lift bucket, the arm and the machine itself to be safe if the tower slipped down further while I was troubleshooting the collapse.

Most crank-up designs are supported by a single cable at each lift.  There simply is no redundancy built in.

Fall preventers might aid, but lacking a way to later safely recover from an activated fall protection system the tower would remain dangerous.

Towers left unserviced until their ropes rot off are difficult to assess for safety – as the most at risk portions of the supporting cables will be difficult to inspect, making it anyone’s guess if the tower can be lowered or if the cable will break.

Hardly a risk worth taking.

About the best plan of action for an at-risk tower would be to insert blocking solid enough to support the tower at each section, remembering to secure that blocking so it can’t fall out.

Then using a man-lift take down the antennas, masts, rotors, feed & control lines, before using a small crane to take the tower itself down.

My previous article on crank-up towers is at: Is a Crank-Up Tower Forever? – Crank-Up Tower Safety & Inspections 

Be safe!

73

Steve

K9ZW

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Doing the Firmware Update on Arraysolutions PowerMaster Meter

PowerMaster with Coupler

 I’ve been a fan of the PowerMaster meter since I purchased an early model from Array Solutions.

 ArraySolutions has continued to improve the product.  The case design show in the photo is the second design, as the early ones have mounting plates on them, for rack mounting.

There has also been a series of firmware and software updates.

I had put off taking the time to do the updates.

A couple weekend ago I went through the process and found it easy.

Download the needed files, run the update program with the unit hooked up to the computer and it is done!

Added a number of Alarm features,  some low power features, appearance features, and some minor updates.

Also took the time to fine tune my personal settings.

Took all of a couple minutes and greatly improved the unit!

73

Steve
K9ZW Logo

 

 

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