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Chelmsford Amateur Radio Society

CARS Meetings: Jan - March 2018

Award for All

27th Mar 2018

Updated the Military Radios talk

January Meeting
Tuesday 2nd January 2018, 7:30-10pm
Oaklands Museum, Moulsham Street
Justin Johnson G0KSC

For the first CARS meeting of 2018 we were privileged to have guest speaker Justin Johnson G0KSC, antenna developer and founder of the highly successful InnovAntennas company.

Before the talk started we first thanked Ian Leonard who was retiring from Oaklands museum and had been our host for numerous evening meetings.

Peter M0PSD thanking Ian Leonard of Oaklands Museum

Justin came to talk to us about his recent developments with Stacking Yagis and modifying other traditional designs to get enhanced performance Logs, Quads and Multibanders. The meeting was very well attended with many visitors from other clubs.

A great turnout for a cold early January evening

Stacked dual-band yagi & quad antennas with intermediate enhancement passive elements

XR3-NV tri-band yagi and new optimised multi-band log periodic

By careful design and some inspiration, Justin had produced designs which enhance certain parts of the bandwidth covered (Amateur bands) without much detriment to the remaining coverage by shifting lengths and spacings of the elements.

As Tony Gilbey G4YTG said: "Thanks Justin, keep it up! We need innovators like you in the antenna business, where most users regard it as a black art."

Justin being presented with his CARS Speaker mug

Useful Links:-

  • Justin G0KSC Antenna designs:
  • InnovAntennas:

    February Meeting
    Tue 6-Feb-2018, 7.30-10pm
    Oaklands Museum, Moulsham Street
    "RSGB Past, Present & Future"
    By Keith Haynes G3WRO

    The February meeting featured a unique perspective by Keith Haynes G3WRO, RSGB Regional Manager as well as an after-break talk by John G8DET.

    Keith's talk started with some history and nostalgia from the early days, moving onto the present including the sheer scope of the hobby and RSGB services.

    It also included an insight to the increasing popularity of the Bletchley National Radio Centre which is seeing 2000-3000 visitors/month (peaking on weekends such as 432 visitors on Sunday 10-Sep-2017).

    The slides had some early history on radio and amateurs:
    1924: Virmani wrote from India to Gerald Marcuse, G2NM
    Feb 1941: ARRL send food parcels to relieve rationing hardship

    RSGB today - services - more than just RadCom and the QSL bureau

    Keith gets his CARS Speaker mug from Tony G4YTG

    Peter M0PSD with some announcements and Chris G0IPU ready with the raffle

    Useful Links:-

  • RSGB: Services Map
  • RSGB: Region-12

    Freeview Changes - John G8DET

    After the break John G8DET who had been experimenting with his TV aerials, gave a talk with slides provided by Murray G6JYB regarding the imminent changes to UHF TV as the 700MHz channels (UHF CH49-60) are cleared by Ofcom ready for more mobile phone usage. This has implications for diplexers, filters, aerial groups and potential loss of some HD.

    John G8DET on 700MHz Clearance and Freeview changes

    Change info:-

    March Meeting
    Tue 6-Mar-2018, 7.30-10pm
    Oaklands Museum, Moulsham Street
    "Military Radios for Amateur Radio"
    By Andy Tyler G1GKN

    To a packed house with over fifty present, Andy Tyler G1GKN talked about using ex-military radios for amateur radio – particularly the Clansman series which are widely available. As Andy said - Go Green, Go Military!

    The slide presentation started with early history with classics such as the ones below (and before SSB)

    Classic Radio Models

    There is a wide variety of models (esp ex British Army Clansman models) that are now surplus on eBay and elsewhere. Andy gave detailed guidance on what to avoid, as well as more interesting models that can be adapted to amateur bands.


    • PRC 349 Inter-Section Portable (37-47 MHz)
    • PRC 344 Forward Air Control (UHF - 225-400MHz)

    Clansman HF

    • PRC 316 (A16) - 2-7MHz, 4 Watts - and crystal channels only
    • PRC 319 Special Forces - 1.5-40MHz, 5W / 50W
    • PRC 320 HF Backpack Portable - CW, AM and SSB (Most USB-only), 2-30 MHz, 100Hz steps 3W/30w - quite popular
    • VRC 321 Vehicle-borne HF Transceiver (28V Base station version of the 320)
    • VRC 322 High Power Vehicle-borne HF Transceiver (up to 200W)

    Clansman VHF

    • PRC 350 Inter-platoon Backpack - 36 to 57MHz FM, 2W
    • PRC 351 Inter-platoon Backpack/Vehicle - 30 to 76MHz FM, 4W
    • PRC 352 Inter-platoon Backpack/Vehicle - a 351 with a 20W PA (and optional vehicle TUAAM/ATU)
    • VRC 353 VHF FM Vehicle Transceiver - 30 to 76MHz FM, 50W

    Non Clansman

    • RT 320/2 Base station version of the 320/1 - 2-30MHz (in 1kHz steps), 10W (or 100W with PV1311 PA)
    • PTR 2311 2-30MHz in 100 Hz steps, USB, LSB and AM, 20W (or 100W with PV421 PA)
    • PTR 2411 30 to 88MHz FM 25 kHz steps, 20W (8 memories, LED display)
    • PTR 5300 Base station or Backpack - 2-30MHz, USB, LSB and AM, 10W (or 100W with PV5320 PA)

    Siemens-Plessey PTR-5300 HF Transceiver

    One unusual design was the Groundsat PTR3411 which was able to act as a full-duplex repeater with simultaneous transmit and receive on the same analogue channel - a clever trick!! - Designed and built by Plessey (Chris Richardson G3NAE)

    Other info covered antennas, audio accessories, Morse Key, Hand Generator, various power and connection boxes and PSUs / battery packs


    Radios on display and Andy getting his CARS Mug from Tony G4YTG (pics by John G8DET)


    More close ups

    Our thanks to Andy for an excellent, thorough and popular talk - as well as Chris G0IPU for the raffle and Ann and Myra for the tea/cakes refreshments

    Useful Links:-

  • (Auctions)

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