IC-T90A external power question
 

I'd like to make an external high capacity pack for my T90A
for emergencies, long special events etc. The manual isn't
very clear on this subject. I'd appreciate any comments from
those who experimented with it.

I notice that when the wall-wart charger is plugged in, the
HT won't transmit (or if it does, it has minimal power) even
when the battery pack is attached and well charged. It isn't
surprising that the normal little charger is not able to put
out enough current, so the unit must be somehow disconnecting
the battery pack when the power plug is in, and tries to draw
all the juice from the external source.

So I'm thinking of making a waist-belt pack out of 8 NiMH or
6 alkaline C or D cells (so it won't exceed the 11.5V max), a
3A fuse, plugged into the jack where the charger goes. Has
anyone done that? I'm 90% sure this will be OK, since the
charger jack is supposed to work with the ICOM cig lighter
adapter so nothing inside should go up in smoke even at full
transmit power with this arrangement. But some first-hand
experiences would reassure me quite a bit. Thanks a lot.

--
Eric Behr | NIU Mathematical Sciences | (815) 753 6727
| http://www.math.niu.edu/~behr/ | fax: 753 1112

In article ,
(Eric Behr) wrote:

I'd like to make an external high capacity pack for my T90A
for emergencies, long special events etc. The manual isn't
very clear on this subject. I'd appreciate any comments from
those who experimented with it.

I notice that when the wall-wart charger is plugged in, the
HT won't transmit (or if it does, it has minimal power) even
when the battery pack is attached and well charged. It isn't
surprising that the normal little charger is not able to put
out enough current, so the unit must be somehow disconnecting
the battery pack when the power plug is in, and tries to draw
all the juice from the external source.

So I'm thinking of making a waist-belt pack out of 8 NiMH or
6 alkaline C or D cells (so it won't exceed the 11.5V max), a
3A fuse, plugged into the jack where the charger goes. Has
anyone done that? I'm 90% sure this will be OK, since the
charger jack is supposed to work with the ICOM cig lighter
adapter so nothing inside should go up in smoke even at full
transmit power with this arrangement. But some first-hand
experiences would reassure me quite a bit. Thanks a lot.

On mine, when the batteries are fully charged the T90 indicates Hi-V
and does not transmit. I assume that it is in self protect mode at that
time.

The manual says not to transmit with the charger plugged in (IIRC).

If I were building a battery pack, I think I would keep it at or under
11 volts for recharging or 8.2 volts for operating. (8.2 is what I see
on turn on whrn the battery has been fully charged.)

de KD5YVP

In article ,
(Eric Behr) wrote:

I'd like to make an external high capacity pack for my T90A
for emergencies, long special events etc. The manual isn't
very clear on this subject. I'd appreciate any comments from
those who experimented with it.

I notice that when the wall-wart charger is plugged in, the
HT won't transmit (or if it does, it has minimal power) even
when the battery pack is attached and well charged. It isn't
surprising that the normal little charger is not able to put
out enough current, so the unit must be somehow disconnecting
the battery pack when the power plug is in, and tries to draw
all the juice from the external source.

So I'm thinking of making a waist-belt pack out of 8 NiMH or
6 alkaline C or D cells (so it won't exceed the 11.5V max), a
3A fuse, plugged into the jack where the charger goes. Has
anyone done that? I'm 90% sure this will be OK, since the
charger jack is supposed to work with the ICOM cig lighter
adapter so nothing inside should go up in smoke even at full
transmit power with this arrangement. But some first-hand
experiences would reassure me quite a bit. Thanks a lot.

On mine, when the batteries are fully charged the T90 indicates Hi-V
and does not transmit. I assume that it is in self protect mode at that
time.

The manual says not to transmit with the charger plugged in (IIRC).

If I were building a battery pack, I think I would keep it at or under
11 volts for recharging or 8.2 volts for operating. (8.2 is what I see
on turn on whrn the battery has been fully charged.)

de KD5YVP

In article ,
Joe Aurelio wrote:
In article ,
(Eric Behr) wrote:

I'd like to make an external high capacity pack for my T90A
for emergencies, long special events etc. The manual isn't
[...]
On mine, when the batteries are fully charged the T90 indicates Hi-V
and does not transmit. I assume that it is in self protect mode at that
time.

Hmm, I've never ever seen that. Mine just says CHG_F and happily
transmits (unless the wall-wart is plugged in).

The manual says not to transmit with the charger plugged in (IIRC).

With the small wall-wart charger, yes. But it is less clear in
case of the "drop-in" rapid charger, and under the cigarette
lighter adapter CP-19 heading it explicitely says "the BP-217
can be charged while you are operating", so I'm assuming there
is no general prohibition on transmitting while external power
is plugged in. That's what made me consider a self-made pack.

If I were building a battery pack, I think I would keep it at or under
11 volts for recharging or 8.2 volts for operating. (8.2 is what I see
on turn on whrn the battery has been fully charged.)

I suppose it's better to play it safe, but 9.6V is well within
the stated maximum. Still, a lower voltage might work just as
well (given enough current), because the manual also says that
"power supply range is 5.5 - 11.5 V", and then that "maximum
output power is 5W regardless of P/S voltage". So they must be
using some intermediate power conditioning circuit. If that is
the case, maybe I'll start with a 6V pack to be on the safe side
and see what happens.

Thanks for the comments de KC9DUX.

--
Eric Behr | NIU Mathematical Sciences | (815) 753 6727
| http://www.math.niu.edu/~behr/ | fax: 753 1112

In article ,
Joe Aurelio wrote:
In article ,
(Eric Behr) wrote:

I'd like to make an external high capacity pack for my T90A
for emergencies, long special events etc. The manual isn't
[...]
On mine, when the batteries are fully charged the T90 indicates Hi-V
and does not transmit. I assume that it is in self protect mode at that
time.

Hmm, I've never ever seen that. Mine just says CHG_F and happily
transmits (unless the wall-wart is plugged in).

The manual says not to transmit with the charger plugged in (IIRC).

With the small wall-wart charger, yes. But it is less clear in
case of the "drop-in" rapid charger, and under the cigarette
lighter adapter CP-19 heading it explicitely says "the BP-217
can be charged while you are operating", so I'm assuming there
is no general prohibition on transmitting while external power
is plugged in. That's what made me consider a self-made pack.

If I were building a battery pack, I think I would keep it at or under
11 volts for recharging or 8.2 volts for operating. (8.2 is what I see
on turn on whrn the battery has been fully charged.)

I suppose it's better to play it safe, but 9.6V is well within
the stated maximum. Still, a lower voltage might work just as
well (given enough current), because the manual also says that
"power supply range is 5.5 - 11.5 V", and then that "maximum
output power is 5W regardless of P/S voltage". So they must be
using some intermediate power conditioning circuit. If that is
the case, maybe I'll start with a 6V pack to be on the safe side
and see what happens.

Thanks for the comments de KC9DUX.

--
Eric Behr | NIU Mathematical Sciences | (815) 753 6727
| http://www.math.niu.edu/~behr/ | fax: 753 1112