VHF+ WEAK SIGNAL STATIONSPART 1 - OVERVIEW AND 6 METERS

FRED KEMMERER, AB1OCJULY 2020

Why VHF+ Weak Signal?

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• All you need is a Tech License• Antennas are smaller and easier to put up• There are lots of new modes and associated propagation

characteristics to learn about. Some are exotic including:• Meteor scatter• Aurora• Satellite communications• Rain and airplane scatter• EME (Moon Bounce)

• There are new technical challenges to be mastered, especially on the bands above 70 cm (450 MHz)• These challenges more closely match modern wireless technologies

• VHF+ contesting is more relaxed and generally less taxing• Operating awards are unique and a step beyond HF

• VUCC and DXCC are the main ones

VUCC Award

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• Earn a VUCC for working & confirming 100 or more grid squares• Available on all bands from 6 m up• Special VUCC for satellites (cross-band)

What Can You Do?

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• Make SSB and CW contacts, someover great distances• 6 m DX – Europe, South America, even Japan• 2m/70 cm – Work states, DX using EME and Satellites• Higher bands – Work states, DX using EME, limited Satellites

• Make Digital Contacts using WSJT-X Modes• FT8 is the most common mode on the 6m band and is used on 2m

and higher• JT65 is used for EME• 2 m APRS is used with certain Satellites and the ISS

• Make “exotic” contacts using scatter Modes• 6 m Meteor Scatter is the most common (via MSK144)• Auroras can support CW and SSB contacts on 6 m• Specialized WSJT-X modes for rain & airplane scatter on 2 m & above• EME (Moon Bounce)

VHF+ Bands

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• 6 m, 2 m, and 70 cm are easiest bands to access

• Support for 23 cm is becoming common in modern radios

• Bands above 23 cm will likely require power to be generated at the antenna

• The 9 cm band is at risk for reallocation by the FCC

• Need to pay close attention to MPE limitsat your station on these bands

• There may be geographically-based power limits on some bands

Operating Basics• Calling Frequencies (MHz)

– 6 m: 50.125 SSB, 50.090 CW, 52.525 FM– 2 m: 144.200 SSB, 144.100 CW*, 146.520 FM– 1.25 m: 220.100 SSB, 220.100 CW*, 220.500 FM– 70 cm: 432.200 SSB, 432.100 CW*, 446.000 FM– 33 cm: 902.100 SSB, 902.100 CW*, 927.500 FM– 23 cm: 1296.100 SSB, 1296.100 CW*, 1294.500 FM

• Start with SSB/FM calling channels and move up to make contacts• In contests, start on 6 m or 2 m and move stations up the bands• If 10 m becomes short, its time to check to see if 6 m is open• Use PSK Reporter to monitor band conditions on 6 m• Use http://aprs.mennolink.org/ to monitor propagation on 2 m• Use https://www.dxmaps.com/ to monitor propagation on 10 m and

above

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Monitoring Propagation for VHF+

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2 Meter Tropo Propagation -http://aprs.mennolink.org/#

DXMaps – Shows Propagation from 10 Meters up –http://dxmaps.com

Color of lines indicate type of propagation – Sporadic-C, Mult-Hop Es, EME, Aurora, Meteor Scatter, etc.

What Equipment Do You Need?

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Antennas and Feedlines• Most terrestrial weak signal VHF+ work is done with horizontally polarized

antennas• Directional antennas are not essential on 70 cm and below but are very helpful

on all VHF+ bands – use one if building a weak-signal station for these bands• Satellite communications benefit greatly from circularly polarized antennas –

generally requires different antennas than terrestrial work• EME benefits from X-Pol systems on and below 70 cm, CP above• Need to pay close attention to minimizing feedline losses

What Equipment Do You Need?

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Radios• Many modern HF radios also cover the 6 m band• Many 2 m/70 cm/[23 cm] rigs include decent weak signal capabilities• Getting on additional bands will likely require transverters - stations for

these bands benefit greatly from radios designed to support transverters

IC-7300 – HF + 6 m

IC-9700 – 2 m, 70 cm, 23 cmIncluding Satellites

IC-7610 – HF + 6 mIncluding Transverter Support

33 cm Transverter, 50W

What Equipment Do You Need?

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• Power• Basic stations can have fun with radios or transverters in the 50 w – 100 w

range (plan on at least 100 w for 6 m)• Some modes (Meteor Scatter and EME) will require at least 500 w to make

more than a few contacts• Other gear

• Low-noise, antenna mounted preamps with proper sequencing are very beneficial on bands 2 m and above, especially if feedlines are long

Software Choices for FT8, etc.

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WSJT-X• Reference standard, latest features

and updates• Full suite of WSJT-X Modes including

MSK144• Supports Contests and Field Day

JTDX• More FT8/JT65 decoder options and

controls• Noticeably better decode performance

on 6 m• Enhanced QSO selection & automation

VHF+ Weak Signal StationsThree Scenarios

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• I just want to do 6 m• Best choice would be a modern HF radio that has 100 w out on 6m

(ex IC-7300)• Start with a modest size 3 element Yagi (can mast mount and use Armstrong method to

rotate)• Install good quality feedlines (LMR-400) and connectors (N type preferred)• Plan to primarily operate using a computer and FT8• If you want to do Meteor Scatter, add a 500 w amplifier

• I want to focus on 2 m, 70 cm, and possibly Satellites• Best choice would be modern VHF/UHF radio with Satellite capability (ex. IC-9700 – 100

w on 2 m, 70 w on 70 cm, 10 w on 23 cm)• Start with modest size Yagis (4 elements on 2 m, 8+ elements

on 70 cm)• Install good quality feedlines (LMR-400) with N connectors• Consider installing coax-powered LNAs near your antennas• Plan to operate SSB, FM, CW, and FT8 using a computer• Will need specialized antennas for serious Satellite work

• I want to do everything on 6 m and above using many bands• Select a Transverter capable radio that also does 6 m (IC-7610 is a modern choice. The

Elecraft KX3 can do the job with an external amplifier for 6 m – not rec. for a new station)• Antennas and Feedlines as above, consider hardline coax & preamps• Might want to think about a modest tower(s) and a rotator

A First 6 m Station Example

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• Icom IC-7300 Transceiver• M2 Antennas 6M3 on a 20 ft guyed, de-rated

push-up mast• LMR-400uF Coax Feedlines• Laptop computer running WSJT-X• Operating Goals – earn a VUCC on 6 m

IC-7300 – HF + 6m

6 m Es Propagation

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• The most common propagation mode on 6 m is E-Skip (Es)• Single-hop Es is good for up to 1,200 miles; multi-hop is possible

• Openings to Europe and the West Coast are common• Best times of year for Es are June-August and November• Most contacts on 6 m are made using FT8, limited SSB/CW

https://pskreporter.info/pskmap.html

6 m Aurora Propagation

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• Auroral propagation occurs when the Earth’s magnetic field is disturbed by CME’s and Solar Flares

• Auroral propagation will typically open the 6 m Band for half of the United States

• Audio will be distorted but CW and SSB operations is possible

6m Station Example – AB1OC-AB1QB

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• Modern Icom Radio/Flex SDR and 500w Amplifier• 7 element Yagi on a 35’ tower, SteppIR DB36 w/6 m Kit, 7/8” hardline feedlines• Mix of SSB, CW, FT8 and MSK144 Modes• Confirmed 460 Grids, 70 DXCCs, all but 2 states on 6 m in ~ 3 yrs.

http://wg7j.reinalda.net/gridmapper/gridmapper.php

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6 m Station At AB1OC-AB1QB – A Closer Look

• Three antennas on two towers – M2 Antennas 6M7JVHD @ 40 ft, two SteppIR DB36’s with 6 m kits @ 65 ft and 105 ft• 7/8” hardline feeders, N-connectors throughout

• Flex6700 SDR (primary) and a variety of Icom Transceivers• SDR is equipped with Transverters/Amps for the 2 m, 70 cm, and 23 cm bands

• Elecraft KPA1500 Amplifier (we seldom use more than 150 w except for Meteor Scatter)• JTDX and WSJT-X software is used for digital operations (FT8/MSK144/JT65)

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6 m (Remote) Operating Dashboard

• Station is run over a wired Ethernet Network, Flex SmartSDR supports this• Use JTAlert and DXLab with JTDX/WSJT-X to identify new Grids/DXCCs and work them• Use Dimension4 for clock sync, run a local GPS-based NTP time server on our network

• Internet based NTP sources (other than Windows time) work fine• PstRotator is used to turn antennas remotely• Elecraft KPA1500 App is used to remote Amplifier and monitor SWR• RealVNC used to connect to a PC in our shack to handle Antenna Switching• Can also power station up/down via the Network and Internet via RemoteGW

Example 6 m FT8 Contact

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• IMPORTANT: 6 m (and above) digital etiquette – Transmit in the same segment as local stations working DX

• Correct segment for calling CQ always be the ODD (15/45) segment when band is open to Europe

• This is important to avoid disrupting weak signal and DX contacts by other stations

Operating Using 6m Meteor Scatter

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• Follow the 6 m etiquette guidelines• Use WSJT-X software, MSK144 mode, disable or set “slow” AGC action• Transmit continuously for 15 sec, hoping a meteor will burn up• Receive and decode “pings”• Early mornings during Meteor showers is best, point 230O to 260O for best results• PSK Reporter can evaluate propagation

https://www.amsmeteors.org/meteor-showers/meteor-shower-calendar/

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In Conclusion

• If you have a 100 w and any antenna for 6 m,give it a try!• WSJT-X modes will certainly produce some contacts

• Use PSK Reporter to evaluate your signal and propagation• Improve your station as your interest, skills, and resources

allow• Select appropriate Transceivers and Directional Antennas

when purchasing equipment to enhance your VHF+ station• Consider your long-term VHF+ goals and plans when purchasing a

Transceiver and other equipment for your station

• Up next – weak signals on 2 m and above• Propagation• Antennas and Radios• Operating

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Questions and Referencesz

• Getting Started with WSJT-X and FT8• An Overview of JTDX• Articles on 6 m Operating and Station Building• Getting Started with EME• Getting Started with Satellites• M2 Antenna Systems• Advanced Receiver Research Preamps

More information on VHF+ station design, construction and operation is available at:

https://stationproject.blog