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MGRC White Noise Newsletter
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Maple Grove Radio Club
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If you are having trouble reading this newsletter in your email client try turning off "Dark Mode." Also, you can always read it online from the newsletter archives.
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MGRC Mission Statement
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Maple Grove Radio Club provides education to current and future amateur radio operators, with the goal of serving the public. We are a reliable communications resource for events and emergencies in Maple Grove and surrounding communities.
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President’s Message November 2023
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The building committee has decided a good option for a better shack at the Legion post is to get an office trailer, the kind you see at construction sites. With a 10’x40’ foot trailer, we would be able to have a training room that can fit 15 people, and a generous 10’x10’ shack. These units usually come with a heat-pump style HVAC system, so we should be able to use it year-round.
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A new trailer is clearly outside our price range. It would take more than the savings of MGRC, and it would be very difficult to get grants for that much. And I can speak for most members and say we want to spend only a small fraction of our savings on this.
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We’ve looked at 3 trailers over the last month. The first one was unacceptable. The second one, 12’x56’, is pretty good, but it would take a significant amount of time to fix up. We saw one last week in much better shape, at 10’x40’, which would still take a lot of work but much less. But this one sold right away.
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But let’s talk about the elephant in the room. Volunteerism at MGRC has been down for the last few years. It took us longer than it should have to get our little shed together, and very few people are using it. It’s going to take quite a bit more work to get a trailer rigged up. If we are going to do this, we should get a commitment from everyone in the club to volunteer to work on it. If half the membership commits 5 hours, that would be enough to get us started. If you can’t commit to that, then you should vote “No” to the project.
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Be sure to attend our meeting on Tuesday, I think we have a lot to talk about.
73
Benton Jackson, K0BHJ
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S.W.R. and Coaxial Cables
For the past two months, a group of people from the Maple Grove Radio Club met for a technical talk
about S.W.R. (Standing Wave Ratio), coaxial cables and touching on antennae concepts. This tends to be
a very broad and intensive subject if we choose to drill down into its depths. There were eleven people
all together at each of the past two meetings. This coming month, as we meet again, we intend to
continue to review some previous topics, making more positive ties from this theory into license
examination questions, and continue with the coaxial cable and antennae. We will make a better effort
to physically fabricate a coaxial cable connector with some hands-on demonstrations, albeit more visual.
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Just a few excerpts from our evening discussions about coaxial cables. It was felt that some key points
on this subject are worth sharing with all operating Hams. Below are some of the basic number(s) to
keep in mind when selecting coaxial cable or evaluating your existing setup. A key number to remember
in our Ham activities and to take away from this reading is the following: For every 3dB (decibel) of
power increase or power decrease, this relates to a 50% increase or loss, respectively, by the time your
signal reaches a load, dummy load or more commonly, your specific antenna. Of course, your antenna
S.W.R. mismatch, antenna losses all add to your goal of E.R.P. or Effective Radiated Power going out and
over the air. Antennae gain (dBi) will be upcoming. For conversation, if your station is starting off with
10 Watts of power from your favorite rig, by the time you add in the above losses, i.e., Coaxial Cable
loss, S.W.R. loss or reflection, Antenna losses, your actual radiated power will be less than what you
might think.
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Consider the following cable types:
- RG-58. This is the smaller diameter coaxial cable on the market, typically just under 0.2” in
diameter. The losses for this cable, at 10 MHZ are 1.1 dB per every 100 foot of length or 0.55 dB
for 50 feet. At 150 MHZ, the loss is 4.1 dB per 100 feet or approximately 2.1 dB for 50 feet. This
is a high loss for and is not a recommended cable for VHF application. It is limited to 530 Watts
at 50 MHZ. Referenced from Belden 8240.
- RG-8X. This is a medium sized diameter coaxial cable and is a very popular choice among Hams.
It is typically about 0.24” in diameter and is easily routable and bendable. The losses for this
cable, at 10 MHZ, are 0.9 dB per every 100 feet of length or 0.45 dB for 50 feet. At 150 MHZ, the
loss is 3 dB per 100 feet or approximately 1.5 dB for 50 feet. The loss of this cable is much
better than RG-58, described above, but its losses are still noteworthy. It is good for H.F. and
quite reasonable for VHF work. For H.F. applications, this cable is limited to 1KW and derated at
VHF. Referenced from Belden 9258.
- RG-8. This is a larger sized diameter coaxial cable and is a reasonably popular choice among
Hams and is the higher performing choice than items 1 or 2 above, only being limited by its unit
higher cost It is considered a “low loss” device. It is typically about 0.4” in diameter and is not as
easily routable or bendable as its smaller counterparts described here. The losses for this cable,
at 10 MHZ, are 0.6 dB per every 100 feet of length or 0.03 dB for 50 feet. At 150 MHZ, the loss is 2.4 dB per 100 feet or approximately 1.2 dB for 50 feet. This cable is a much better choice if it can be afforded and is an excellent choice for H.F. and V.H.F. but does show an appreciable loss (4.2 dB) in U.H.F. (400MHZ) areas. Again, cost versus performance is the compromise. For H.F. applications, this cable will handle the full legal limit but derated to 1,280 Watts at VHF. Referenced from Belden 8237.
- LMR400: This is a very similar sized cable to the RG-8 cable, described above, but does have some notable higher performance features, i.e., larger inner conductor, higher quality insulation's, improved shielding factor and improved power loss factors. This all comes with a slight cost increase from the RG-8.
Decibel Power Losses by the numbers:
- 0.5 Decibel loss: 11%
- 1 Decibel loss: 21%
- 2 Decibel loss: 37%
- 3 Decibel loss: 50% (AKA the half-power level).
- 4 Decibel loss: 60%
- 5 Decibel loss: 68%
- 6 Decibel loss: 75%
All cables described above have a characteristic impedance of 50 Ohms. As their quality or performance
improves, ranging from adequate to better, such as items 1, 2, 3 and 4 above, respectively, their
“Velocity Factor” (speed of electrical impulse) improves also. Cable length specifications described
above are 50 feet and 100 feet, respectively trying to mimic lengths in actual practice. At your location,
it can be all too common to have 50 feet or more in running lengths. I emphasize that all cables are a
compromise, i.e., unit cost versus performance. Note: I have found dB loss specified values vary, for the
same cable type, from manufacturer to manufacturer.
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Below is a link to an on-line RF power calculator. There are many of these types available for your
convenience.
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If members are interested in this type of technology and more, you are invited to attend one of our
monthly workshops which are held the 1st Monday of each month at 5pm.
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Maple Grove Radio Club in-person meetings!
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In-Person meetings are on the first Tuesday each month.
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The meeting starts at 1900 hrs (7:00pm CDT) at the Chester Bird American Legion Post 523 located at 200 Lilac Drive N Golden Valley, MN 55422. Here is a link for directions.
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Stephen Cullen, KF0AED, will be giving a review and overview on Metro Skywarn and their activities.
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Meeting ID: 948 0429 0777
Password: 674964
Phone: 1-312-626-6799
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MGRC Weekly Practice Net
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Our weekly Net is on Wednesdays at 20:200 UTC (8pm), on 147.000, positive offset, tone 114.8. We use directed Net protocol and will have a new question for discussion every week. Please call in if you can reach the K0LTC repeater.
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We need a Net operator for the 3rd Wednesday of the month. If you'd like to receive Net operator training please contact President@k0ltc.org.
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TALARC The American Legion Amateur Radio Club
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TALARC has approved MGRC members in good standing to be honorary TALARC members. If you are interested contact Stephen Cullen, KF0AED at kf0ade9@gmail.com. Please include your Name, Callsign, Email, and when you joined MGRC, if known.
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Classes
Lab Class
- 1st Monday of every month at 5pm
- The Lab Class will meet November 6 at Gordon Patenaude's house: 10909 Independence Ave. N. Champlin, MN. 55316. Topic continues to be on S.W.R. and antennas. Please let Gordon know if you'll be coming.
Info: Gordon Patenaude- WA0WSR.
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General License Class, Fall 2023
- ‼️Monday evenings - started October 9th, and runs for about 10 weeks.
- To get answers to your questions, email registrar@mnyarc.org
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MGRC COMMITTEES AT WORK
BUILDING COMMITTEE
Chair: Jerry Dorf – N0FWG
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- Lot's to discuss!
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Normally, First Thursday - November 2nd already met!
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Next Meeting - 6:30 December 7th.
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See calendar for details.
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TALARC
Chair: Tim Arimond – N0BYH
o Shack is operational with HF and VHF/UHF stations.
o Honorary memberships.
▪ Contact Stephen Cullen if interested. KF0AED9@gmail.com
▪ Just need to be an MGRC member in good standing to be eligible
o Meetings 4th Thursday of each month at 7pm.
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November Club Calendar of Events
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Board Members
• President: Benton Jackson – K0BHJ (2018)
• Vice President: Zack Whitney – K0ZTW (2021)
• Secretary: William Oliver – KF0ADU (2022)
• Treasurer: Paul Odens – K0AID (2023)
• Trustee K0LTC: Jerry Dorf – N0FWG
• Board Member: Tim Georgi – KD0SFH (2018)
• Board Member: Kelly Murphy – KB0LTY (2019)
• Board Member: Clay Bartholow – W0LED (2021)
• Board Member: David Englund – K0NOC (2022)
• Board Member: Gordon Patenaude – WA0WSR (2023)
• Board Member: Stephen Cullen – KF0AED (2023)
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