Message-ID: <000901c083ed$fe2ca380$cac928c3@ericadodd>
From: "g3ldo" <g3ldo@ukonline.co.uk>
To: rsgb_lf_group@blacksheep.org
Subject: LF: Pyrotechnic insulators and CT1DRP
Date: Sun, 21 Jan 2001 21:05:21 -0000
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My antenna is a sort of two-wire inverted (cross between an inverted L and a
V) as shown in Fig 4.9 of the LF Experimenter's Handbook.
The top spacer was insulated from the mast by a couple of ceramic insulators
shown in Fig 4.10.
While testing this antenna prior to the VE1ZZ tests a dramatic and noisy
pyrotechnic display occurred across one of these insulators . I lowered the
antenna and cleaned the insulators and the problem seemed to go away. But it
occurred again. I inspected the insulator and found it was cracked all round
and that the top spacer was only held by the other insulator.
I modified the antenna so that the spacer was fixed directly to the mast and
the wires supported by a couple of PA0SE brown ceramic insulators. The
antenna was tried several times and, apart from a reduction in antenna
capacitance, it worked fine.

Today I had a phone call from Brian, CT1DRP. We have conducted several tests
in the past - he has received my 136kHz and 73kHz signals and I have
received his 136kHz signals but we never have had a QSO. Brian had renewed
his mast (damaged in gales) and cut lopped some trees and could now get
2amps into his antenna with 200watts. We decided on a QRSS QSO. I checked
the band at 1630 and it was clear of signals. Due to some restrictions we
decided on 136.4kHz (at the risk of being 'flamed' again on e-mail by a
couple of CW only operators).
I transmitted to Brian and he transmitted to me - we were both receiving
each other very well. When I put it over for an acknowledgement of my
report -nothing! The receiver was dead. The problem turned out to be the
antenna. The nylon cord fixing the insulator to the spacer had broken - no
sign of any burning.
It had been raining heavily all day today.
I replaced the nylon cord with copper wire and tried again later. This time
(1820) we made it, conditions not so good with the signal down and QRN up.

Brian is going to improve the operating set-up. He also has a Decca
transmitter so look out for a good signal from CT1 in the future.

Regards,
Peter, G3LDO

<g3ldo@ukonline.co.uk>