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ARRL (Page)

WHAT IS THE ARRL?

The ARRL, the National Association for Amateur Radio (ARRL) is the national association for amateur radio (ham radio) operators in the United States, founded in 1914. The ARRL recognizes SFARC as a special service club for our commitment to the local community and emergency

Small ARRL LogoIts main roles include:

  • Advocacy & representation for amateur radio with the FCC and international regulators
  • Education & licensing support, including study materials and exams
  • Operating activities like contests, awards, and emergency communications programs
  • Publications, most notably QST magazine
  • Emergency communications, coordinating volunteer hams during disasters via ARES (Amateur Radio Emergency Service)

From The Desk of the ARRL

10/23/2026The ARRL Solar UpdateThe active sunspot region that has been giving us improvedpropagation over the past several days will be rotating awayfrom Earth’s view today, but conditions on most of the HFamateur bands should remain pretty decent in the days ahead,as the 10.7-centimeter radio flux remains right around 100.Howeve… READ MORE
10/16/2026eBay Restricts Listings of Radio Equipment, but Exempts Ham-Band-Only GearImageOnline marketplace eBay has imposed new restrictions on listings of radio transmitting equipment in response to new FCC rules that took effect this week, but responded to ARRL The National Association for Amateur Radio® that its new policy will not apply to gear that operates exclusively on ama… READ MORE
10/16/2026Florida Hams Provide Communications Support During Hurricane IsaiasAmateur radio operators from Florida’s Santa Rosa, Nassau, Lake, Pinellas, and Leon Counties played an important role in supporting emergency communications efforts during and following Hurricane Isaias, helping ensure that critical communication capabilities remained available throughout the storm.… READ MORE
10/16/2026The ARRL Solar UpdateLook for improved propagation on the upper HF bands, as both thesunspot numbers and 10.7-centimeter radio flux remain near or above100. According to NOAA's Space Weather Prediction Center (SWPC),the increase in activity is being fueled primarily by sunspotRegion 4551, which is described as the large… READ MORE
10/14/2026The 2026 ARRL Online Auction Is Now OpenThe 21st annual ARRL Online Auction, sponsored by GigaParts, is open now through October 22. Browse more than 200 items and place your bids!This year’s selection includes gear from QST “Product Review” articles, vintage books, pre-owned equipment, signed original sketches by Salty Walt Hudson, K4OGO… READ MORE

Check out all the ARRL has to offer by visiting their website @ https://www.arrl.org/ Continue reading ARRL (Page) →

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Interactive Band Plan (Tile)

INTERACTIVE BAND PLAN

The ARRL band plan is a PDF you squint at, scroll through, and eventually give up on. The following is the same information made usable and interactive.

Search a frequency or a mode and jump straight to it. Filter by license class to see exactly where your privileges begin and end. Every segment is color-coded by mode, so you can tell at a glance whether you’re about to call CQ in the middle of the digital watering hole.

Covers 2200 meters through microwave. Works on your phone in the field, on your laptop at the operating desk, and in color-blind-friendly and light modes.

A band plan is a voluntary agreement among operators to keep incompatible modes out of each other’s way. It is not the law, Part 97 is. Always check current FCC rules before transmitting.

SFARC SPECTRUM EXPLORER

A band plan is a voluntary division of a band to avoid interference between incompatible modes.

Where can I operate?
  • CW
  • Phone / SSB / AM
  • Digital / Data
  • FM / Repeater
  • Beacons
  • Satellite / EME
  • ATV / SSTV
  • Experimental
  • Other / Shared
Based on the ARRL Band Plan. Locally coordinated plans always take precedence.

DOWNLOAD

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What is Five Nine? (Tile)

WHAT IS FIVE NINE (5 9) AND WHAT DOES IT MEAN?

The R-S-T system is used by amateur radio operators, shortwave listeners, and other radio hobbyists to exchange information about the quality of a radio signal being received. The code is a three-digit number, with one digit each for conveying an assessment of the signal’s readability, strength, and tone. The code was developed in 1934 by amateur radio operator Arthur W. Braaten, W2BSR.

The R stands for “Readability“. Readability is a qualitative assessment of how easy or difficult it is to correctly copy the information being sent during the transmission. In a Morse code telegraphy transmission, readability refers to how easy or difficult it is to distinguish each of the characters in the text of the message being sent; in a voice transmission, readability refers to how easy or difficult it is for each spoken word to be understood correctly. “Readability” is measured on a scale of 1 to 5.

The S stands for “Strength“. Strength is an assessment of how powerful the received signal is at the receiving location. Although an accurate signal strength meter can determine a quantitative value for signal strength, in practice, this portion of the RST code is a qualitative assessment, often made based on the S meter of the radio receiver at the location of signal reception. “Strength” is measured on a scale of 1 to 9.

The T stands for “Tone” and is measured on a scale of 1 to 9. Tone only pertains to Morse code and other digital transmission modes and is therefore omitted during voice operations. With modern technology, imperfections in the quality of transmitters’ digital modulation severe enough to be detected by human ears are rare.

Readability

Strength

5. Perfectly readable

9. Extremely strong signals

4. Readable with practically no difficulty

8. Strong signals

3. Readable with considerable difficulty

7. Moderately strong signals

2. Barely readable, occasional words distinguishable

6. Good signals

1. Unreadable

5. Fairly good signals

4. Fair signals

3. Weak signals

2. Very weak signals

1. Faint—signals barely perceptible

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Understanding RFI (Tile)

Understanding RFI

RFI happens when electromagnetic signals from one device disrupt the normal operation of another. These signals can be intentional (like a radio transmitter) or accidental (like electrical noise).

Common Sources Include:
– Cell Phones & Wi-Fi Routers
– Power Lines & Electrical Motors
– LED Lights & Switching Power Supplies
– Computers, Monitors, USB cables
– Vehicle Ignition Systems
– Radio/TV Transmitters
– EV Car Chargers
– Solar Inverters

Interference occurs when unwanted radio-frequency signals disrupt the use of your television, radio, or cordless telephone. Interference may prevent reception altogether, cause only a temporary loss of signal, or affect the quality of the sound or picture produced by your equipment.

How Can I Reduce It?
– Shielding (metal enclosures, braided cables)
– Filtering (ferrite beads, line filters)
– Better grounding
– Physical separation between noisy and sensitive devices
– Good cable routing and design

Sometimes you can take all of the above steps and STILL have RFI issues.  When in doubt, check out additional resources from the American Radio Relay League or file a report with the Federal Communications Commission (FCC).

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22 Things You Can Do With Ham Radio (Tile)

22 Things You Can Do With Ham Radio

Somewhere above your head, right now, there’s a satellite you could talk through. There’s a balloon sending back weather data. There’s a stranger in Japan who’d be delighted to hear from you.

Amateur radio — ham radio — is the hobby that gets you there. You build the gear, you make the contact, you keep talking when the internet quits. No subscription, no algorithm, no waiting for permission. Just you, an antenna, and everything the sky will carry.

Here are 22 places to start.

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All About Connectors (Tile)

ALL ABOUT CONNECTORS

Choosing the right RF connector matters more than it looks. The wrong choice can add loss, raise SWR, let water into your feedline, or simply fail to mate with your gear. This guide compares two of the most common coaxial connectors in amateur and commercial radio — the PL-259 (UHF) and the N Type — and then summarises the other connectors you are most likely to meet: SMA, SMB, MMCX, MCX, TNC and BNC.

PL-259 vs. N Type at a glance

Property PL-259 (UHF) N Type
Coupling Threaded (5/8″-24) Threaded (5/8″-24), precision interface
Impedance Not a true constant-impedance design (nominally 50Ω) Constant 50Ω (75Ω version also made)
Practical frequency range HF/VHF, generally to ~300 MHz DC to 11 GHz (precision versions to 18 GHz)
Weatherproofing Not weatherproof on its own Weatherproof when correctly mated (gasket/O-ring)
Power handling High at HF/VHF; robust body High, with better consistency at UHF and above
Cost & assembly Cheap, easy to solder, very forgiving Dearer, more parts, needs careful assembly
Typical use HF/VHF ham rigs, CB, antenna tuners UHF/microwave antennas, Wi-Fi, cellular, test gear

PL-259 (the “UHF” connector)

Despite the name, the PL-259 is best thought of as an HF and VHF connector. It dates from the 1930s, when “UHF” meant anything above about 30 MHz. The plug is the PL-259 and the matching socket is the SO-239 (the “PL” and “SO” come from old Signal Corps nomenclature for plug and socket).

It is not a true constant-impedance connector — there is a noticeable impedance discontinuity through the joint — so performance falls away as you climb in frequency. Its strengths are that it is inexpensive, mechanically tough, easy to solder onto thick coax like RG-8 or RG-213, and almost universal on HF and VHF amateur equipment.

Rule of thumb: fine to about 300 MHz; above that, expect rising SWR and use something better.

N Type

The N Type was developed at Bell Labs in the 1940s by Paul Neill (the “N” is for Neill). Unlike the PL-259 it is a genuine 50Ω constant-impedance connector, which makes it well behaved all the way up to 11 GHz, and to 18 GHz in precision versions. Properly mated it is weatherproof, which is why it is the default choice for mast-mounted antennas, Wi-Fi and cellular systems, and microwave links.

The trade-offs are cost, a few more parts to assemble, and the need for more care during termination.

Careful: a 75Ω variant exists for broadcast and CATV work. 50Ω and 75Ω N connectors should not be mated — the differing pin diameters can damage them.

Which should I use?

For HF and VHF on a budget, or to match existing ham gear, the PL-259 is hard to beat. For anything outdoors, anything above ~300 MHz, or where low loss and a clean match matter, choose N Type.

Other common RF connectors

Beyond these two, a handful of smaller connectors turn up constantly in modern radios, antennas, modules and test equipment. The table below summarises the essentials; brief notes follow.

Connector Coupling Impedance Typical max frequency Where you’ll see it
BNC Bayonet (quarter-turn) 50Ω & 75Ω ~4 GHz (50Ω) Test gear, oscilloscopes, video/SDI, older networking
TNC Threaded 50Ω (75Ω made) ~11 GHz Threaded “BNC” for vibration/microwave environments
SMA Threaded (1/4″-36) 50Ω (75Ω rare) 18 GHz (to 26.5 GHz) Wi-Fi, GPS, handheld antennas, RF modules, test gear
SMB Snap-on (push) 50Ω & 75Ω ~4 GHz Tight spaces needing quick, repeated connections
MCX Snap-on (push) 50Ω (75Ω made) ~6 GHz GPS, cellular, compact devices (~30% smaller than SMB)
MMCX Snap-on (push) 50Ω ~6 GHz Wi-Fi/M.2 cards, tiny antennas, IEMs — smaller than MCX

Quick notes

BNC
A fast bayonet lock that is the workhorse of the test bench. The 50Ω type is for RF; the 75Ω type for video. Convenient but not for high microwave frequencies.
TNC
Essentially a threaded BNC. The screw coupling makes it far more reliable under vibration and pushes the usable range up to around 11 GHz.
SMA
The small threaded connector you find on most Wi-Fi and GPS antennas and on countless RF modules. Excellent to 18 GHz, but the threads have a limited number of mating cycles, so don’t treat it as a frequent connect/disconnect joint. Watch out for RP-SMA (reverse-polarity), which is common on consumer Wi-Fi gear and will not mate with standard SMA.
SMB
A push-on snap fit that is quicker than SMA in cramped assemblies, at the cost of a lower frequency ceiling.
MCX / MMCX
Progressively smaller snap-on connectors for space-constrained devices such as GPS modules, laptop wireless cards and compact antennas. MMCX adds a little rotational freedom, handy for routing thin cables.

A note on the names: several of these share a heritage. N is for Neill, BNC is Bayonet Neill–Concelman, and TNC is Threaded Neill–Concelman — so the B and T simply tell you how the connector locks.

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70CM (440) Repeater Features & Functions (Page)

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70CM (440) REPEATER FEATURES

The W6EK 70cm (440) repeater is a Yaesu DR2X repeater installed in 2019. Coordinated with the NARRC on 440.575MHz, + 5 offset, CTCSS 162.2, operating in AMS mode providing both C4FM and FM modes at 40 watts with coverage of the greater Auburn and Eastern Sacramento, California region.

In C4FM digital mode, local RF coverage is complimented by a Wires-X connection to the NorCal Repeater Group #43847 and bridged to the YSF node US-NorCalRptGrp #YSF06040 hosted on a remote server. The default C3FM connection is linked to repeaters located in Galt, Elk Grove, Georgetown and Mt. Rose (serving Lake Tahoe, Truckee and the greater Reno region).

The repeater is capable of operating in either analog FM or digital C4FM modes (Yaesu AMS). Analog FM users will hear a digital hash sound during C4FM digital transmissions unless the analog FM RX Squelch is set to CTCSS 162.2. If FM mode is used to access the repeater, the transmission will only be heard locally from the W6EK 70cm RF transmitter. FM mode transmissions will not be heard on the NorCal Repeater Group Wires-X repeaters or by YSF nodes.

Wires-X Inbound
Connect to the W6EK 70cm repeater via any Wires-X enabled repeater, or directly from an internet-connected Yaesu radio using the personal node mode (PDN), The Wires-X room is: NorCal Repeater Group (43847).

Wires-X  Outbound
You may redirect the W6EK 70cm repeater to connect via Wires-X mode to any Wires-X-enabled repeater or node. In C4FM digital mode, the Wires-X button on a Yaesu-branded Fusion radio directs the room selection. If there is no activity on the user’s selected node or room for 10 minutes, the Wires-X connection will automatically disconnect and return to the default NorCal Repeater Group room. It is best practice to manually return the repeater back to the default NorCal Repeater Group (43847) room after completing use of the redirected connection.

70cm Repeater YSF
Connect to the 70cm repeater in YSF mode and the NorCal Repeater Group repeaters via any YSF or FCS-enabled repeater, bridge, personal node, or smartphone app. The W6EK 70cm repeater’s YSF node is: US-NorCalRptGrp (YSF06040).

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2M Repeater Features & Functions (Page)

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2M REPEATER FEATURES

The W6EK 2-meter repeater is a Yaesu DR2X installed in 2020. Coordinated with the NARRC on 145.430 MHz, -.6 offset, CTCSS 162.2, operating in FM mode at 85 watts with coverage of the Western slopes of the Sierra Mountains and across the Sacramento Valley in Northern California.

The transmitter is located near downtown Auburn at 1600’ elevation with three remote RTCM voter receivers. The main voter receiver is located East of Auburn on Mountaintop @ 2130’ elevation. The second voter receiver is in South Rocklin @ 520’ AMSL and the third at the Georgetown airport @ 2625’ AMSL. Internet access is available via Allstarlink node # 51018, Echolink node # 4128 and monitored on Broadcastify.

AllStarLink Inbound
Connect to the 2m repeater via AllStarLink from any ASL enabled repeater, node, computer or smartphone app. The W6EK 2 meter repeater’s ASL node number is 51018.

Echolink Inbound
Connect to the 2m repeater via Echolink from any Echolink enabled repeater, node, computer or smartphone app.  The W6EK 2 meter repeater’s Echolink node number is 4128.

Broadcastify
Listen to repeater traffic through the Broadcastify.com website service or using a smart device with a scanner app. The repeater audio channel is: W6EK 145.4300 MHz Sierra Foothills ARC Repeater – https://m.broadcastify.com/listen/feed/32073

Mountaintop RTCM Voter
Rocklin RTCM Voter
Georgetown Airport RTCM Voter

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