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G8MNY > TECHNI 01.02.26 18:19l 78 Lines 2573 Bytes #1 (0) @ WW
BID : 51134_GB7CIP
Read: GUEST
Subj: Using a G5RV on 160M
Path: JH4XSY<N3HYM<W9GM<VE3CGR<OK2PEN<GB7CIP
Sent: 260201/0912Z @:GB7CIP.#32.GBR.EURO #:51134 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Aug 13)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
To use a G5RV or any HF dipole/doublet conveniently to a Marconi T aerial on
topband you will need..
1/ A good earth
2/ A matching coil
3/ Double Pole Relay/switch
4/ Outdoor Box
AERIAL
Tree 2nd
Supports Support
- -oﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾒﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄo- -
Insulator ｺ
Balancedｺ
Feederｺ
ｺ
ｺ
ｺ
ｺ
Switched===================Coax to shack
Matching ｳEarth
Box ｳstakes
ｳ
SWITCHED MATCHING BOX
This has to house the relay or manual double pole high voltage switch with the
loading coil.
Balanced
Feeder
ｳ ｳ
ｳ oﾄﾁﾄﾂﾄﾄﾄﾄﾄﾄﾄ(((()
RL1ｳ_/o o RL2 L /ｳ\
ｳ o\_________ｳ
ｳ ｳ_ ｳ
ｳ ｳ/| ｳ
ｳ === C ｳ ___
ｳ /ｳ ﾀﾄﾄﾄﾄﾄﾄﾄﾄ)___Shack
ﾀﾄﾄﾄﾁﾄﾄﾄﾂﾄﾄﾄﾄﾄﾄﾄﾄﾂﾄﾄﾄﾄﾄﾂﾙ Coax
Earth ﾚﾄﾄﾁﾄﾄｿ _ｳ_
Stakes ｳRelayｳ \_/
ﾀﾄﾄﾂﾄﾄﾙ ｳ Select
ﾀﾄﾄﾄﾄﾄﾁﾄﾄﾄ<160M
This circuit is with no HF balun for use on a G5RV or half sized G5RV. If a
dipole is used with then a switched balun & more complex switching is needed.
With the relay released L is shorted out & the feeder is connected to the coax
in the normal way.
With the relay operated the feeder is shorted together & connected to the coax
via the L & a SWR triming cap C. The voltages can be very high (1kV) so a relay
or switch with good contact separation & contacts to spacing is need.
TUNING
Generally a series L (tapped 60 turns on a 3cm dia former) is all that is
needed to get the resonated Z down to near 50/75� with most aerials. But if the
SWR is still to high at resonance the C across the coax (via RL2 contact) of
100-2000pF should bring the Z to an exact match.
BOX
A black plastic box is best. Hermetically sealed boxes really don't seal that
well outdoors. A better approach is to leave a breathing hole in the bottom
(lowest point) so that any water can drain way, but put a fine mesh over it to
stop insects. Paint up & spray all parts with a light oil to resist rusting.
Grease up well, all screws & connectors use outside so any water has no where
to go.
Why Don't U send an interesting bul?
73 de G8MNY @ GB7CIP
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