Saturday, December 10, 2011

10 GHz FAQ

  1. Why is 10 GHz becoming so popular and what FCC license is required?
    • Top 10 Reasons Link
    • Challenge: It used to be 10 Meters and then 1296 MHz and now 10 GHz has become the "must have" band for weak signal operators looking for a new challenge. Requiring only a technician license, you can work other "gigaheads" from a local hilltop, your tower or beside a road with moderately priced and/or surplus equipment that's become available.
    • Momentum: The ARRL and many local organizations have events that focus on 10 GHz activities which then attract an increasing number of participants.
    • Camaraderie: 10 GHz attracts a great bunch of guys and gals who will go out of their way to give you a hand!
  2. Will a 10 GHz DSS dish antenna meet there FCC CC&R antenna exclusions?
    • The availability of the DSS offset dish (used and often free from Directv, Dish, etc) has been a major stimulus and provides up to 30 dB gain on 10 GHz. This facilitates long range communications with relatively low power levels.
    • Often a modified DSS dish appears similar to a satellite TV dish and may be acceptable in antenna restricted areas.
  3.  Can I mount a 10 GHz antenna onto my existing tower and aim it correctly?
    • Yes but you'll need to deal with the relatively high transmission line losses at 10 GHz by co-locating your transverter and/or amplifiers near/on the dish feed point. 
    • You'll need to "plum" (relatively vertical) your mast (side or top mounted) with rotational accuracy of +/- a degree or two for proper dish aiming.
    • Elevation control is optional for local some rain-scatter opportunities.
  4. Will 10 GHz signals propagate beyond the visual "line-of-sight"?
    • Yes, you'll be surprised at the range that you'll be able to operate.
      • Building reflection/refraction -
      • Topo -
      • Ducting -
      • Rain/show/sleet scatter -
      • EME -
  5. How much RF power is required for the various 10 GHz propagation modes?
    • Barefoot transverters (without external power amplifiers) with up to 200 mW output on 10 GHz can propagate your weak signals 100's of Kms.
    • Combined transverter/amplifiers with up to 2-3 watts output on 10 GHz can be successful on 1000's of Kms.
  6. What is a 10 GHz transverter and will it work with my existing transceiver?
    • A transverter converts 10 GHz transmit and receive RF signals to/from an Intermediate Frequency such as 144 MHz transmit and receive RF signals.
    • Many popular multi-band, multi-mode transceivers already have 2 meter CW/SSB capability and will drive a 10 GHz transverter as long as you reduce the 2 meter power output to match the transverter drive requirement.
  7. What modulation modes are used for 10 GHz communication? 
    • SSB is most popular with FM used when signals are relatively strong and CW used when signals are relatively weak.
  8. What protocol is used to make 10 GHz contacts? 
    • Most contacts are scheduled in advance or coordinated on a lower frequency band. During contests contacts are possible by tail-ending other QSOs, as long as antennas are pointed in the right direction. 
  9. How do 10 GHz contests differ from the other VHF/UHF contests?
    • There are many operating events during which 10 GHz is popular: ARRL Jan., June & Sept.;  10 GHz & Up, SBMS 2 GHz & Up, Spring & Fall Sprints, MAD (Microwave Activity Days) and anytime when EME conditions are favorable.
    • During ARRL VHF/UHF contests you can transport multiple 10 GHz stations within a single vehicle. 
    • On the "10 GHz and up" event you can coordinate via any communications (cell, Internet, etc.)
  10. How can I get started on 10 GHz and what will it cost?
    • The best way is to contact your local weak signal organization and ask to use a loaner station for the next scheduled 10 GHz event! 
    • The biggest initial cost is a 10 GHz transverter. Used and kits range from $300 on up, depending on the model, power output and vintage. A DSS dish antenna can usually be found free of charge with minimal modifications required.
    • Once you determine your level of interest and what kind of station works best for you, you'll want to upgrade your equipment, over time.
 Please submit your questions for inclusion on this list.

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Friday, December 9, 2011

NLRS "Loaner" Microwave Stations - Configuration/Status

Given the importance of "loaner" rigs for promoting microwave activity, it's in our best interest to make them available to any and all newbies. It's always up to the equipment owner to arrange for loaning to people that you know and are comfortable with. (This list is automatically updated when you add to and/or update your entries into the Google Docs spreadsheet.)


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Thursday, December 8, 2011

10 GHz KISS (Keep It Simple Simon)

Keeping your 10 GHz station simple will help save costs, failures and your sanity!
If you're new to 10 GHz you'll want to start with a basic hardware configuration and learn what's important. Then you can upgrade as necessary, over time.
Much of the information presented is meant to inform you of what's possible rather then what's necessary. 

A "simple" station includes the following major components:
  • Transceiver, Transverter, T/R Relay, Antenna/Feed and DC Power Source

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Wednesday, December 7, 2011

10 GHz Facts-of-Life

  • Go to a good location 
  • Your aim needs to be spot-on 
  • Best propagation - mornings & evenings 
  • It's helpful to be on frequency


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      Tuesday, December 6, 2011

      10 GHz "Top 10 Reasons"

      1. Most active microwave band
      2. An additional contest band
      3. Visit great operating sites
      4. Get to know a great bunch of operators
      5. Learn new operating protocols
      6. Recycle you old satellite TV dish
      7. The challenge and "zing" of success
      8. Teach an old ham, new tricks
      9. Become a "rare" grid again
      10. Experience weird propagation
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        Monday, December 5, 2011

        10 GHz Propagation

        Rainscatter is but one of the 10 GHz propagation modes. 

         





        Aircraft Scatter Propagation using JT65C Digital Mode:


         









        Tropo propagation can be very mysterious.



         EME (Moon Reflections)




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        Saturday, December 3, 2011

        10 GHz IF Transceiver Alternatives

        Yaesu FT-290RII

        The  transceiver (transmit and receive radio) also known as in IF-Rig is a key component within a 10 GHz station. It's purpose if to convert an IF (Intermediate Frequency) signal to and from an audio frequency for your microphone, headphone and/or speaker. There are many choices available to the newcomer and you'll probably upgrade overtime. Some considerations are:
        1. Multi-mode - usually SSB, CW and Digital for weak signal operation
        2. 144 and/or 432 MHz bands - direct or via intermediate transverter
        3. Low power output - from 0 dBm up to several watts; depending on the transverter drive
        4. Good frequency accuracy and stability - for finding weak signals on 10,386.100 MHz
        5. Digital frequency display - for accurate frequency readout
        6. Adequate selectivity - for filtering out the noise (QRN) more so than other signals (QRM) 
        7. Back lite indicators - for low-light operating environments
        8. Low power consumption - when powered from batteries in the field
        9. Low weight and small form factor - for mounting on portable, tripod based stations
        10. Useful built-in features:
          • CW keyer for both QSOs (under very weak signal conditions) and beaconing
          • Panoramic and waterfall visualization of weak signals
          Examples of common, direct-IF transceivers are:
        FT-817





        Costs run from around $200 (used FT-290) up to $1000 for a new FT-897D
          Examples of common, indirect-IF (via intermediate transverter) transceivers are:

          HTX-100


          • Flex-1500 - 500 KHz - 54 MHz IF range (using the 0 dBm XVTX/C and/or XVRX connectors)


          Costs range from around $150 (used HTX-100) up to $1500 for an Elecraft K3 kit

          Also, an experimental, indirect-IF transceiver kit is available:

          DIY - No-Tune SSB/CW Transceiver for 10GHz - S53MV

          Transverters should always be considered a poor technical solution for many reasons. Receive converters usually degrade the dynamic range of the receiver while transmit converters dissipate most of the RF power generated in the base SSB transceiver. Both receive and transmit converters generate a number of spurious mixing products that are very difficult to filter out due to the harmonic relationships among the VHF/UHF amateur frequency bands......Matjz Vidmar, S53MV


          Transceiver Comparison Tables











          The Care and Feeding of Transceivers: 

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            Friday, December 2, 2011

            10 GHz Intermediate Transverter Alternatives

            Indirect-IF Transceivers require an external, intermediate transverter in order to provide either a 144 or 432 MHz IF for use with the 10 GHz transverter. Some examples are:

            W1GHZ Miniverter





            Kuhne 2 Meter Transverter









            Costs range from $59 (Miniverter kit) up to $350 for the Elecraft K144XV

            Intermediate Transverter Comparison Table 

             The Care and Feeding of Intermediate Transverters 

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            Thursday, December 1, 2011

            10 GHz FLEX/DEMI-1500&144IF 2 Meter Transceiver

            The purpose of this mash-up is to package the PCBs from a DEMI L144-28INT intermediate transverter and DEMI ApolLO synthesizer within the covers of a modified FLEX-1500 transceiver while retaining the ability to revert back to the original multiband FLEX-1500 configuration. My FLEX-1500 is used primarily as in IF transceiver. I've been looking to reduce the number of cables and boxes for my 10 GHz station configurations. When Down East Microwave Inc. (DEMI) announced a small form factor 2 meter intermediate transverter I just had to try and package it within my FLEX-1500.

            FLEX-1500
            DEMI L144-28INT










            Dis-assembly of the FLEX-1500


            Assembly of the "FLEX/DEMI-1500&144IF" Transceiver


            Initial Results:
            • High performance IF transceiver with up to 100 mW (linear) RF output on 2 meters. Note that my unit measures 180 mW output on 2 meters which is sufficient to drive my DB6NT 10 GHz transverter, 3 Watt DEMI amplifier and 8 Watt DEMI amplifier to full power output!
            • Both the transceiver and transverter are locked to an external 10 MHz reference frequency.
            • DC power consumption is reduced by the removal of the FLEX-1500 HF/6 band hardware.
            • Simplified PTT control via common RF connector to external, microwave transverters.
            DEMI L144-28INT kit Assembly Considerations:
            • There are two semiconductor packages that I hadn't seen in a kit before. They are the SOT-89 PHA-1 monolithic amplifier and TTT167 SYM-18H mixer, both of which were a challenge to install on the PCB. Pre-tinning the PCB, precise component alignment and careful soldering are a must for the safe installation of these devices. DO NOT overheat these devices (like I did)!
            •  Due to the PCB width and wire/component placement near the PCB edges, the +9V overflow wires need to be soldered directly to the voltage regulator pin rather than the designated PCB +9V plated-through holes that are too close to the PCB edge.
            • Up to 3 relays are used depending on your configuration (1 for RF switching, 1 for IF switching and 1 for mode switching). All of them need to be mounted on the top, component side of the PCB; not the bottom as shown. This is to provide adequate clearance within the enclosure. Note that you'll need to change the RF and/or IF relay +12 VDC source from TXON to RXON if you locate these relays on the top side of the PCB.
            • My output RF (144 MHz) configuration uses a single BNC connector for both TXRF and RXRF thereby eliminating an external relay. You can configure with two BNC connectors for separate TXRF and RXRF, if necessary.
            DEMI VHF ApolLO Integration Considerations:

            •   Mounting of the ApolLO within the Flex-1500 enclosure is a bit of a challenge. You need a clean 12 VDC power source, a clean 10 MHz signal source and a short 116 MHz signal distribution to the intermediate transverter LO input.
            • I chose to sandwich the ApolLO PCB in between the Flex-1500 and DEMI-L144-28INT PCBs near the front panel for minimum LO cable length.
            • The 116 MHz output is connected to the intermediate transverter just after the crystal oscillator output and before the LO amplifier that drives the mixer. The LO signal levels were approximately the same between the crystal oscillator and the ApolLO. 
            • There is a provision for an optional LED that indicates "lock" but I chose not to use it.
            • The 10 MHz reference frequency input is a separate BNC connector in addition to the Flex-1500 10 MHz reference frequency input BNC connector. No attempt was made to combine and/or re-power these within the enclosure as there is already enough RF floating around within the enclosure.


            Packaging and Interconnection Considerations:
            •  I chose to use a new enclosure so as to not modify the original FLEX-1500 enclosure and provide better access. The Hammond HM979-ND ($21.50 from Digi-Key) has the same dimensions but with a sliding bottom useful for mounting the DEMI L144-28INT PCB. You can use the original FLEX-1500 enclosure if you don't mind drilling additional mounting holes in the bottom or use a different intermediate mounting plate.
            • A new rear panel was patterned from the FLEX-1500 back panel from brass plate stock (K&S Engineering 2" wide X 0.065" thick cut to 4.06" long). It also functions a a heat sink for the +5V regulator required for the FLEX-1500 PTRX PCB. The original FLEX-1500 back panel would have worked if I had used only a single, common IF output connector.
            • Be careful to not reverse the Ground and +5V plugging into the bottom connector of the FLEX-1500 PTRX PCB. I'd recommend checking your connections with an ohm meter BEFORE power is applied! Remember that one side of the connector has 3 ground pins (away from the BNC connectors) and that there are two pins for +5V. Take a close look at this picture. +5VDC is the ONLY voltage that you need to apply to the PCB (NOT +12V)!
            • I used a VHF ApolLO as the 116 MHz local oscillator so the analog oscillator components were not used. This did require a connector on the back panel for a 2nd 10 MHz reference frequency input (separate from the transceiver 10 MHz reference frequency input).
            • Other than these items, all three of the PCBs fit inside the enclosure and the original FLEX-1500 front panel was reusable without any modification.
            • More information on the FLEX-1500 can be obtained from the free service manual (available on request to FLEX-1500 owners).
            • The overall weight was increased by 4 oz (0.11 kg)  from 1 lb 5 oz (0.61 kg) to a total of 1 lb 9 oz (0.72 kg).

            Cooling Considerations: 

            •  Use of the VHF ApolLO synthesized 116 MHz local oscillator eliminated all sources of frequency drift.
            • However, in order to meet all three of the PCB component operating temperature limitations, additional cooling was needed. Note that the ApolLO synthesizer PCB may not lock up if its recommended temperature range is exceeded.

            • A combination of air escape holes drilled into both sides of the enclosure and a bottom mounted, thin fan (2 1/4" x 2 1/4" x 3/8" thick) were added to force air through the enclosure thereby lowering the external case temperature down from 95'F to 80'F (with only 9 VDC applied to the fan for lower noise level).
            • This change increased the effective height of the enclosure by 3/4 " to a total of 2 3/4".

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                  10 GHz Transverter Alternatives

                  >>under construction<<
                  A 10 GHz transverter converts RF between an IF (Intermediate Frequencies of usually 144 or 432 MHz) and 10,386 MHz. They're available in many form factors, with various power outputs, from several vendors or DIY (Do It Yourself) articles. You can check-out new or used units on Ebay and microwave oriented swapfests. Several examples are:
                    10368-144 FA&T or Kit from DEMI 





                     MKU 10 G3 FA&T or Kit from KUHNE








                    DIY 10 GHz Transverter Projects:
                    1. DIY transverter @ KO4BB
                    10 GHz Transverter Comparison Table
                      The Care and Feeding of 10 GHz Transverters 

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                        10 GHz Receive Pre-amplifier Considerations

                        The last potential upgrade on your list would probably be a receive pre-amplifier. Unless you have an unusual situation, you'll probably not see much benefit. Unusual situations include:
                        1. Lossy transmission line between your antenna and 10 GHz transverter.
                        2. 10 GHz transceiver with a poor noise figure (that can't be fixed).
                        3. EME operation with low background noise where every fraction of a dB counts.
                        KC0IYT - Glen has pointed out that you may be able to test your current receive sensitivity by just pointing your antenna towards a noise source (houses, people, trees, etc.) and monitoring for an increased noise level compared to the open sky background noise. Compare noise figure specifications between different transverters and receive pre-amplifiers to determine if the potential improvement is worth the expense and additional complexity.
                        Commercial receive pre-amplifier sources:  
                        Kuhne MKU LNA 101AS

                        DEMI 3-2ULNA
                        Costs range from around $100 (kit) up to $250.

                        Surplus receive pre-amplifier Source - Modified KU band LNA's

                        • K0AWU - Bill uses a surplus KuBand LNA to provide about a 1db NF and 20db gain to overcome superflex cable loss on the receive path from his tower to shack.



                              Potential Benefits of Receive Pre-amplifiers:
                              1. Overcome receive path losses from transmission lines, adapters, relays, connectors, etc.
                              2. Optimize the transmit path without concern for the receive path, if a choice is necessary.
                              3. Improve your station's noise figure to compensate for a poor or remote transverter.
                               The Care and Feeding of Receive Pre-amplifiers:
                              1.  Must be connected directly to a low-loss antenna relay for maximum benefit.
                              2. The potential for severe overload from other stations nearby and/or on adjacent frequencies dictate that you reduce the gain in the receive path down stream of the receive pre-amplifier. A lower gain receive pre-amplifer (single stage, >12 dB) may be better than a higher gain unit (dual stage, >22 dB), depending on your station configuration.
                              3. Pre-amplifiers must be well protected from any RF power using relays with high isolation.
                              4. Proper sequencing becomes more important to insure that protection relay(s) have completed switching before any RF power is applied.
                              5. Never allow your antenna relay to be switched during a transmission!
                              6. Filtered DC voltage is necessary to avoid injecting power supply noise.
                              7. Unterminated receive pre-amplifiers can go into self oscillation.
                              8. Pre-amplifiers are subject to potentially destructive RF transients from adjacent bands.
                              9. Gain and can deteriorate over time so be sure to measure it while still in new condition.
                              10. Rain, humidity and vibration can degrade your pre-amplifier electronics and/or connectors performance, over time.
                              Receive Pre-amplifier Configurations:
                              >>>under construction<<<



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