Message-ID: <002b01bf1ce4$407390e0$92e1abc3@default>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: "rsgb_lf_group" <rsgb_lf_group@blacksheep.org>
Subject: LF: Technical details of CFH (137kHz)
Date: Fri, 22 Oct 1999 21:58:57 +0100
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Thanks to Jon VE1FTL I have the following interesting details on the system
at CFH. Jon says it is a Canadian Naval site and gives the location as
Newport Corner.

The transmitter is aging valve unit, capable of 25KW, but more usually run
at 8 to 9 kW.
Modulation is FSK +/- 42.5Hz from the nominal carrier. This power
corresponds to 30 to 40 Amps into the aerial, which is what I think would be
called an 'umberella' . The main radiator is about 600 feet tall (Jon hadn't
the exact dimensions to hand)  It is capacitively loaded with a system
consisting of the top 25% of each of the six guy spans with the ends
connected together by a circle of wire, and then 6 more wires running from
the top to the this circular wire. Sounds a bit like the big brother of the
systems Dick was modelling a few weeks back.

The station is off the air for maintenance and will not return until the
Navy requests it. The transmitter is to be replaced by a more modern
solid-state class C unit some time early next year.

I guess there is enough detail there for some of you guys to estimate the
ERP. Ok we dont know what the losses are but I reckon we could make a
reasonable guess.

The plus point on this is that the aerial is about what I had though it
might be, but the power is a lot less (I thought it might be a 50kW unit) so
the margin needed to hear a amateur signal might not be so great. Of course
the 'answer's in the soil' !!

Once again this is all thanks to Jon, ( who is a technician on the site )
who has promised to e-mail me when it is due to return to the air.

73 de Alan G3NYK
Alan.Melia@btinternet.com