FOR HAM RADIO


Welcome Ham Radio Fans

We sliding into 2017 with our magazine, "Topics," a spin-off from group discussions generated daily on 40 meters. Before we start we want to give a special thanks to the Ham Radio Morning Crew Sponsors of Group 7155, who have been the sole inspiration for Topics. Had it not been for your radios, antennas, amplifiers, cables, tuners and shacks breaking down and burning up, this magazine wouldn't have the material it has today. And so, we bow to all the ones with nimble fingers and brilliant intuitions, those who seeked and searched to find ways to mend, tape, splice, repair, refinish, retune and recap. And then tell the tall tales. You are Gentlemen all.

73,

Ken O'Neill & Dave "JS" Phillips

Welcome to 2017, Now Learn how to say, "Bigly" -- It was a strange year last year. In general I don't like "Six" years. But I have to say, with the Solar Cycle and other disturbances in bands that allow tv transmissions, it has already proven to be a very weird year indeed. No matter what camp you come from, it is nice to know that 7155 is a political-free zone at sun-up. We hope you join us soon!

 

TOPICS HAM RADIO MAGAZINE

Table of Contents


January 2016 - All About Tuners and Bandscopes
February 2016 - The IF and The Scope
March 2016 - Let's Go On an RF Hunt!
2nd Quarter 2016 - Our Interplanetary Influences (open for write-ins)
Antenna Mythology - Reactance, Resistance, Coils & Trouble

 

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meteor

Sid, K7SID, reported seeing a fireball last night (June 1, 2016). This is a great site to find reports on sightings, check it out and enjoy!

 

Group 7155 Topics - 2nd Quarter 2016

OUR INTERPLANETARY INFLUENCES
Hanging Out with the Mr. Sun

I don't know about you but when I hear someone ask what ham radio all about, the typical beginning of the conversation is about licenses, all the toys, antennas and such. But seldom hear, about signals and how they get to where they are going with relation to the largest influence in our hobby, the Sun. Truth is, you can buy all the amplifiers and build the tallest antennas, but if the Sun has a bad day, watch out, it will make our gear sound like crystal radios.

Our Earth is wrapped in this wonderful invisible magnetic gel pack and when it is poked in the slightest it can set off all manner of minor radio propagation to very real life threatening disturbances. This amazing balance is so very critical with everything in place with such tight precision. And the artistry that is our universe, ah, there is the real wonder. From the tiny atom and it's design that matches precisely the same design as our solar system. There is something to think about! There are as many solar systems in the Universe as there are grains of sand on our plant.

I want to present more about this topic in the next couple of days, so I will leave you with this short list of perfect links to get started. When I come back I'll share more and we'll see where this takes us.

Sunspot Number Graph

BandConditions.com

Live Animated Ionosphere Maps

Realtime Observations of Radio Flux

Alerts and Predictions of Events

Radio Propagation

Understanding Solar Indexes

   
   
   
  Group 7155 - The Ham Radio Morning Crew
  "Topics" created by Ken O'Neill, W6BQZ - The Big Quiet Zebra - Carlsbad, California
   

 

   
 
   
 

Group 7155 Topics - March 2016

TOPICS: LET'S GO ON AN RF HUNT

Books in a pileup

Bad Stuff Begone - RF is Near! Or is it?
Thanks to Group 7155 Sponsors!

Hear that fuzzy tone in your voice? Did you try to clear your throat and nothing happened? And, worse yet, your friends are telling you they hear it too, and it isn't something that you ate that can be cured by mouthwash. It's in your wires and it's not good. You shouldn't live with it one more minute, read on ham dogs (and trust me, you don't wanna become a "ham dog" like they show in the videos below), these precautions are for you!

Wanna Go On An RF HUNT?

RF Meter Trifeld

You should probably start with the article page, RF Exposure - Evaluating Your Station located on the Ham Radio School dot com site. You'll love how the site is laid out and well, old or young, new in the hobby or so long you think you know it all, this site is still for you.

They will take you through the Regulations, the Evaluations and what you need to do to bounce, tromp and be rid of that nasty invisible foe, RF. Because if you don't do something about it, you'll be Really Fried (get it?)

Okay, the gong, I know. But pay attention, this stuff is important.

 

The above meter is from Trifield and please click on the photo and you will find a complete description of how to use it and what measurements it can perform. At least one ham in our group uses that meter and has good luck with it. Below, you will see that there are two other units with different price points that you can also use. There are two other manufacturers that some claim are better, Narda and AR Modular (which may be a lot more expensive).

 

Dave Phillips (KB7JS) writes:

Good subject for conversation, too many people ignore the dangers. This article is focused on VHF transmissions at power levels greater than 50 Watts.   Few rigs actually provide that much power, and not too many hams actually do that, the exception usually those who chase SSB contacts during atmospheric ducting events, Moon Bounce, Sattelites, etc;  Most of us urban Ham’s can hit any number of repeaters with 5 watts,  and don’t run that much power.  Still, those who decide to run higher power put themselves at serious risk by ignoring the issue.  The typical HT user doesn’t realize how dangerous continued and long term exposure to VFH/UHF transmission is present due to the rubber duck antenna so close to their head.  Even at 1 to 5 watts, this can be very dangerous.

To broaden this discussion, I would like to mention that the rapid expansion in use of antenna tuners at the operating position, especially those built in to the transceiver,  also poses the possibility of serious risk for RF exposure for HF operators.  The tuners themselves radiate RF, and the typical use for the tuner is to balance the feed line to an antenna that is not resonant, specifically to make the transmitter happy with low SWR.  However, the SWR on the feed line to the antenna is still there, and when the tuner is in the shack, that reflected RF is always present.

Chris (W7AMD) writes:

Sometimes these things work out quite differently than you expected. The group that I recently retired from AR Modular RF builds RF tactical amplifiers as part of it's product line.  One of them is a 20W wearable PA for the 30-512MHz band.  We were asked to show that operators would be safe to use this amplifier system and compare it to the standard 5W portable unit.  I went through the FCC exercise using input from the services about modes of operation, and timing of transmissions etc., and surprise to everyone the system met the FCC guidelines. Tactical radios have been steadily moving up in frequency in recent years and now that they are using up to 2GHz or so there's considerable interest in "body absorption" levels.

AR makes a line of field strength measurement probes with traceable calibrations similar to NARDA products that cost a small fortune by ham standards. The EMC testing community spends a great deal of time and money to generate and then measure accurately E and M fields in their testing environments.

My input is to use the FCC guidelines.  Keep reasonable distances from high power systems, enjoy the hobby and don't worry too much!

Steve (K0UO) writes:

My group http://rsicorp.com/ uses the Narda 3006 for most surveys, at HF below 300mhz the FCC requires you need to use both E and H field probes for testing, (you could buy 2 new  Icom 7851 rigs or one Narda 3006!).

I did a few FUN  videos which are on YouTube,  this one we cooks a Hot Dog,  don’t try this at home!!! I am using tested High Voltage gloves and a $10,000 Narda test meter:

RF Hot Dog

https://www.youtube.com/watch?v=BVn5OJX1EGw

This one is showing how RF can light things up, around RF leaking cable which is used for in building radio coverage:

 https://www.youtube.com/watch?v=wTohQTl1bAI

Most ham HF stations are very safe, as long and you can’t touch the antenna.

 

If you like what you see here guys, please help the Zebra out if you think you can:

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BREAK TIME:

I know there will be more, but for now while we take a short break, can I interest you in a really interesting Video regarding Induction and Electromagnetism?

Watch the entire Video (ie, dont turn it off if you think it is ending)

Left Hand Rule

http://youtu.be/bht9AJ1eNYc

 


RF Follow Up

Ok, back to RF chasing. We did have some follow ups, and those were directed toward the manufacturers of the measuring devices. One said that the Trifield was not the best and that Narda was far superior. And, since we are noting manufacturers, AR Modular was also mentioned in the article.

That is about all for our RF Section. Thanks for stopping by and giving us a read. If you like what you see, why not write in and let us know.

73 all ... Ken, W6BQZ

 

 

 

BQZebra was here!

Books

TOPICS was started for you, Mom. I miss you and could only wish you had a license up there to transmit from time to time.

   
  Join 7155 Today - Click Here!
   
  Group 7155 - The Ham Radio Morning Crew
  "Topics" created by Ken O'Neill, W6BQZ - The Big Quiet Zebra - Carlsbad, California
 

Group 7155 Topics - January 2016

TOPICS

Books in a pileup

Outdoor Tuners: Quality, Longevity & Users
A Misbegotten Collaboration from BQZebra & Dave's Junk Shop, KB7JS

SGC 230 TUNER

The latest hot topic this past two weeks has been outdoor tuners and how well they operate, or don't operate - even their fail rates. Have something to add? Tune up to 7.155 MHz and chime in.

The door is open. Learn more. Gil, N2GG has found one of the best arrangements for using wires. Pretty simple, you just have to know a few tricks. Stop by, ask him. It's all about pushing out the most power with optimum efficiency. And then you ask,"What about the power limitations these things have?" And, so, it begins . . . .

 

MFJ Tuners

SGC appears to be the big contender and sensible because they are reliable. Then there is LDG with a 600 watt outdoor tuner and good old MFJ with their Legal Limit tuner that seems to be a little prissy when setting up with a short stem of coax and a 4:1 balun. We have already had a fail within the first 3 months of ownership in the group. It's back at MFJ getting repair (or replacement).

And, of course, we're talking automatic which turns the conversation to manual tuners and it went on to why some hams love AM and boat anchors. See what you're missing?


Our own Dave Phillips, KB7JS writes, "Before the birth of SGC, SEA, Stevens Engineering Associates, manufactured a line of HF radio equipment specialized for maritime use.  The brand is still in business but now owned by another company.  They were one of the first to produce a remote automatic antenna tuner that could be used with any HF transceiver as it  did not require channel/frequency data or other control signals from the transceiver, instead it automatically determined the transmit frequency and tuned the antenna load to provide a good match.  The first really successful model was the SEA 1612B."

Here is how the story goes, according to Dave who says, "I found a strange SG-230, at a flee market five years ago, my first encounter with the beast.  I still have it.  It is unlike any SG-230 anybody else has seen, housed in a aluminum enclosure, not water tight.  Of course, being flee market fare, the thing did not work, so I set about trying to repair it, and first task was to get schematics.  I talked myself silly with the "geniuses” at SGC Tech Support, who continued to tell me that I must be mistaken, or I had acquired a Chinese Knock-off, because the tuner did not match any of their model numbers or schematics.

At some time, there was a loss of brotherly love amongst the SEA Associates, and an unknown number of them packed their bags and moved down the road a few miles to start their own company, named SGC.  They immediately began to produce their own HF auto-tuner to compete with SEA in the maritime market, but also had the audacity to market it to other HF users, HAM’s.  The retail price of their tuner was outrageous, in the high 3 digit range, but you know ham’s, they’ll buy anything when they read an Advertisement that says it can perform magic.  The rest is history, SGC sold a hell of a lot of their SG-230 tuners and it’s spin-offs."

 


TOPICS

Books in a pileup

The IF and the Band Scope
Courtesy from Dave's Junk Shop, KB7JS

The IF is simply the conversion frequency.  The input signal is mixed with another signal.  Mixing is simply a process where two different frequencies are passed through the same amplifier stage.  In most receivers, this actually happens two, three, even four time (double, triple, quad conversion). The output of each IF amplifier is a broadband signal that contains both input signals, as well as the sum and product of their frequencies.  It’s like making soup, mix two things together, and get four separate flavors.

After the amplifier, a filter selects the desired mix result, usually the product.  The idea is to obtain an output that always results in the same frequency to facilitate further filtering and processing of the input RF noise. 

This is where it gets a little confusing, but the reason for converting all frequencies into a single frequency is to simplify the remaining receiver circuits so they only have to be designed to interpret one frequency band out of the billions of possibilities. Keep in mind that the VFO on your radio only spans a certain segment of a band, typically 500 kHz,  so the output of the IF amp is usually passed through a 500 kHz filter, so that the output then contains all of the signals within +/- 250 kHz of the IF frequency. That is why your band scope driven from the IF signal can display all the signals within a certain range.  The HDSDR software needs to know what frequency band you are listening to, and then simply does the math to convert the display image of the IF frequency back to the actual signal frequency.  This is computer software massaging the data to make it human readable by interpreting the IF content.

Washing Machine WringerCONVERSION: There are a number of reasons for the different stages of conversion, but the driving force is selectivity and noise rejection.  Converting the original signal to a different frequency also allows it to be cleansed of unwanted noise and heterodyne byproducts, some of which occur within the mixing process itself.  This was much less of a problem in the vacuum tube days since the inherent high impedance of tubes (all that open space in a vacuum between elements) meant that there was very little noise generation.  That is why older tube radios used only single or double conversion designs.  Modern solid state radios with all their digital components self-generate an enormous amount of noise, so the receiver design has to separate all of that from the fundamental HF signal that you want to hear.  Most solid state receivers today will first convert the input signal to a much higher frequency out of the bandwidth of the ham bands, aka “Up Conversion”, typically somewhere in the area of 45-75 MHz.  Then, the signal is converted back down to a more reasonable value for filtering, typically 10 MHz, where it is mixed with the output of the VFO to provide selectivity of the desired center frequency.  Finally, the last stage of conversion will take the input down to a frequency that is easily converted to audio, and the most common frequency for this is 455 kHz.  

The FT-1200 and FT-1000 are classic examples of multi-conversion of an input signal.  The FT-1000 is a Quad conversion receiver, where the signal is converted to 73.62 MHz, 8.215 MHz, 455 KHz, and 100 KHz. The FT-1200 is a triple conversion design, with the first IF at 40.455 MHz. The 1st IF frequency is typically chosen to attack the self-generated noise problem.  In the case of the 1200, they were focused on using DSP to filter noise at a later stage, and selected the 40 MHz range specifically because it was out of the bandwidth of the DSP and would not interfere.

 

TOPICS

And now for something completely different . . .

 

Telegraph Key Picture

US Navy & Wireless Telegraph Keys

For a great read, this is perfect for a rainy afternoon! Just tap the Key above.


 

Topics Files: A New Life for Your FT-101 - Article on QST Hints & Kinks in 1969

 


 

Check this out:

Reference Guide

If you think this is cool (above), you have to see the rest of this PDF by Raytheon. Click Here!


TOPICS

Do You Need An Antenna Tuner? Well, do you? Click Here



Is this the Better SDR?

 


 

Thank You Note Thank You Note from W6BQZ to Group 7155

Hey Guys,

I cannot believe how the site is coming together even more thanks to the kind and thoughtful contributions of several of the Group members. Thanks guys. Thanks for being there, thanks for your help, your contributions above and beyond, and just look at what it has already done for the site. I believe that in the days ahead we will see even more. Group7155.com is definitely here to stay. Let's keep rockin'. You guys are the greatest.

By now you probably have noticed the TOPICS section on the page. Kind of big, isn't it? Well, the plan is to have it's own page you can click to, and to have it grow. So if you have a Topic that you are interested in and find a resource that stands out in a crowd, let me know and I will include it with a reference back to you if you like.

73!

Ken, W6BQZ - The Big Quiet Zebra - Your Web Guy

Join Us Today - Click Here!

Group 7155 - The Ham Radio Morning Crew
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TOPICS
We won't admit it if they ask us . . .

 

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tiger jumping DREAM BIGGER

 

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