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VK5ATN > FT-817 03.01.07 08:00l 58 Lines 2687 Bytes #999 (0) @ WW
BID : 520045VK5ATN
Read: DG1VV GUEST DL1RX VE7HFY DG4IAK
Subj: Voltages and confusion ...
Path: DB0FHN<DB0RGB<DB0MRW<DK0WUE<DB0RES<TU5EX<I0TVL<F6CDD<F6BVP<VK2TV<
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Sent: 070103/0402Z @:VK5ZAR.#ADL.#SA.AUS.OC #:58143 [Broadview] $:520045VK5ATN
From: VK5ATN@VK5ZAR.#ADL.#SA.AUS.OC
To : FT-817@WW
The deserved popularity of the Yaesu FT-817 has resulted in a Yahoo!
internet group of some 8,000+ members. Not surprisingly therefore, the
question of input voltage vs power has been explored many times in that
forum, always with pretty well the same results.
Consensus is that the 817 essentially puts out it's rated 5 watts at an
input voltage of somewhere around 10.5 volts. Anything in excess of this
does not necessarily result in more power being delievered to the antenna,
but is simply disipated as heat within the radio.
Therefore there is little point in taking extra effort to ensure that 13.8
volts is always available at the power socket on the back, with one
possible exception, namely when using the battery charging options which
are designed around a 13.8 volt expectation.
It is certainly NOT advisable to try and increase the supply voltage to
the little rig to above 13.8 volts. The risk of damage is increased
thereby. To supply it with 16 volts is a request - no a *demand* for
smoke to be released from within!
In point of fact many 817 owners opt to reduce the voltage to the input
socket to about 11 - 12 volts anyway to ensure that the rig runs within
the desirable set of parameters; there is even an in-line "conditioner"
kit to buy and build to simplify this.
Incidently the output power icon on the display may blink under these
conditions - this is generally accepted as a 'bug' - the conventional
wisdom is that the rig is still delivering it's full rated 5 watts powered
with an external supply know to be delivering 10.5 volts or a little more,
even though the icon's behaviour suggests otherwise.
Since the 817 needs only about 2 amps at the stated voltage for
satisfactory operation, this should be able to be supplied from any cig
lighter socket without any serious issues. I still use some kind of
filtering and voltage limiting arrangement to guard against the
unexpected.
It's also accepted that the "standard" Yaesu supply lead/plug accesory
does introduce some voltage drop when used in its full length. Whether
this is really serious depends on how much voltage you start with at the
supply end of the cable, and whether you accept the theory that 10.5 volts
or a little more is enough anyway. YMMV!
Finally some heavy vehicles - especially some trucks - use a 24 volt
electrical system, and this is often what you will find present at the
cigarette lighter too. I need hardly stress that this needs special
consideration when you contemplate plugging in any sort of equipment which
expects only half of that figure.
73
Terry
VK5ATN
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