Caradon Hill Repeater Group

Andy

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Joined Nov 3 2011
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MALE
56 years old
Liskeard, Cornwall
About Me

CHRG Chairman :/

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2 Comments

Reply G3TDJ
6:51 AM on February 4, 2012 
CHRG Chair - just a few notes regarding the early days of GB3CH

Caradon Hill Repeater Group - How it all began...

The original idea for a 70 cms repeater in the area was the brainchild of Steve G8EWV in 1975/76. Steve was a mobile operator, travelling regularly between Bude, Callington and Liskard. Steve's enthusiasm and "can-do" approach pulled together the original GB3CH project team of Steve ? G3EWV, Paul - G8AGU and Andy ? G3TDJ.

IBA were approached early in the project study and were very supportive from the outset offering use of the main mast, mains power for the repeater, and the quick-reaction required for emergency close down procedure. Without the enthusiasm of the Caradon Hill Chief Engineer the GB3CH project would never have been the success it turned out to be.

An inaugural meeting was held in Plymouth in 1976 to determine interest and support, and from this gathering came the first committee: Chairman - Andy - G3TDJ, Secretary - Steve ? G8EWV, Treasurer ? Graham - G8MXE and committee members Paul - G8AGU (G0HNW), Alan - G3KFN and Arthur - G3NBX.

Subsequent AGM?s were always held in Plymouth because from the outset the GB3CH group encouraged the ?adoption? of GB3CH by radio societies in Plymouth or Saltash.

Following the success of the inaugural meeting the GB3CH ?road show? was launched to ?sell? the project, encourage interest and raise funds wherever we predicted GB3CH would be heard. Every amateur radio club in a large area from Plymouth through Saltash, west to St. Ives, then north through Newquay and Bude to Bideford , were visited by G8EWV and G3TDJ with lectures and the ?hard sell? for donations and affiliations.

With the site and license agreed, Henry - G8MWW kindly donated an entire Pye 450 MHz PMR transmitter and receiver in a lockable case, G3VX provided RF filters and the RSGB sourced Andrews coaxial cable. Logic was built by G3TDJ using TTL and a few operational amplifiers. All timing was derived from a 28 KHz master crystal clock. The call sign generator used a scanned diode matrix and an FX101 DTMF tone decoder provided 1750 Hz tone-burst detection.

Initial funding was raised to purchase high spec transmitter and receiver crystals, two specially tuned co-linear aerials, mounting brackets and the not insignificant professional rigger costs for aerial installation.

The first record of GB3CH activity between G3TDJ, G8EWV and G8AGU is noted in my log at 1015 on 17th December 1977.

Initially GB3CH took to the air with temporary aerials mounted on the IBA building until professional aerial riggers carrying sufficient damage indemnity insurance to climb and install aerials and feeders on the main IBA mast were contracted.

I well remember a conversation with the Caradon Hill Chief Engineer discussing the safety and insurance requirements for rigging the co-linear aerials. We wanted to fit a mast head amplifier, but we were concerned about lightning strikes destroying the amplifier. We asked if the mast was ever struck by lightning ? ?Oh about every other day? was the reply! ?What about transistor survival? we asked, ?Well all three legs of the semiconductor are raised by the strike and we have never lost a mast mounted amplifier yet!?

So GB3CH got a masthead pre-amplifier which survived many mast strikes. In those days the effect of serious lightning strikes to the mast were very apparent to the television service because all transmission would disappear for 8 seconds while power and monitoring systems stabilised.

Some years later Chris Bartram, G4DGU, joined the committee as the initial team drifted away from the area as work commitments changed.

I see Steve G8EWV very occasionally when he makes a trip back to Bude, he says will also fill in some gaps in GB3CH early history and I believe he has photographs of the original installation and the two co-linears being rigged on the main IBA mast.

I still have my pencil drawn logic diagram for the original GB3CH control.

rgds

Andy

G3TDJ - Bude
Chair GB3CH Group circa 1976 - 1980
Reply kennnnnnnnny
8:22 AM on December 10, 2011 
Andy the Membership is not growing very much on ur new site very slow .
Perhaps a bit more Advertising. I have passed it around within the circle of people that i speak to. Trust all fine there with u and the Family need ur house number for postage of Christmas Card. Regards Kennnnnnnnny