Message 24642 in TECH.WW
From: G8MNY
Date: Wed, 24 Jun 26 07:49:00 Z
Newsgroups: TECH.WW
Subject: FT290/690/790 DC Power mod.
Message-ID: <63255_GB7CIP>
Path: N2NOV|VE2PKT|PY2BIL|GB7CIP
R:260624/0752z @:N2NOV.#RICH.NY.USA.NOAM $:63255_GB7CIP
R:260624/0751Z 11620@VE2PKT.#TRV.QC.CAN.NOAM LinBPQ6.0.25
R:260624/0751Z 45601@PY2BIL.SP.BRA.SOAM LinBPQ6.0.25
R:260624/0749Z @:GB7CIP.#32.GBR.EURO #:63255 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (new Graphics Feb 06)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
_____________________________________
THE ORIGINAL CIRCUIT
+ve outer
WHAT'S WRONG
1/ The original external power jack uses the dangerous +ve outer standard so
that the when connected to other kit there is a risk of shorting.
2/ The jack switch is supposed to disconnect the +ve battery lead when the
external power is applied. This depends very much on the make/type of plug
used, and it is easy to draw high current though the battery pack and cook
the cells and holder and possibly the rig!
3/ An reverse polarity idiot diode is provided, but on the -ve connection. So
if the rig is connected to other kit (e.g. a powered speech processor) the
protection is negated, and the mic lead now carries the rig current!
4/ The Plugtop raw charging (hummy battery) is via a 2.5mm jack socket that
shorts out the charger while being plugged in/out. There is no indication
that the charger is not being shorted out!
Here is my circuit that solves most of these problems...
+ve centre
It uses most of the existing components. The fuse is just 1 cm of very fine
relay wire in case of disaster. The lamp is a wire ended 12V fairy light that
provides low trickle current when the rig is 10-14V powered.
Some rigs also include a small 1000uF 16V by the jacks. The 12V jack is
remarked with a +ve centre with a RED felt pen.
The disadvantage is that there is now a diode in the battery supply lead to the
rig, I feel this is a worth while loss for protecting the battery pack from
damage!
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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