HP204 power supply mods?
 

I have an HP204 with shot rechargable batteries. Has
anyone modified one of these to work just off of
the 120v mains? Looking for suggestions as to how
best to modify this thing.

cheers, Paul - VA7NT email:

Chuck Harris writes:
Excellent, thanks very much.

cheers, Paul - VA7NT

The simplest mod would be to remove the batteries and
replace them with a pair of 12V-13V 1W zener diodes.
You should probably also have a 470uf cap in parallel
with each diode to provide some extra noise and hum
reduction.

TRANS+ --------------+---------+----- OSC B+
| _|_+
____/ ___
/ /\ |
| |
GND------------------+---------+----- OSC GND
| _|_+
____/ ___
/ /\ |
| |
TRANS----------------+---------+------ OSC B-

Or, you could rig up a simple board with a 7812 and
a 7912 as a regulator.

The charger transformer was designed to provide enough
power to charge the batteries, and run the unit at the
same time.

-Chuck, WA3UQV

Paul Erickson wrote:
I have an HP204 with shot rechargable batteries. Has
anyone modified one of these to work just off of
the 120v mains? Looking for suggestions as to how
best to modify this thing.

cheers, Paul - VA7NT email:

Chuck Harris writes:
Excellent, thanks very much.

cheers, Paul - VA7NT

The simplest mod would be to remove the batteries and
replace them with a pair of 12V-13V 1W zener diodes.
You should probably also have a 470uf cap in parallel
with each diode to provide some extra noise and hum
reduction.

TRANS+ --------------+---------+----- OSC B+
| _|_+
____/ ___
/ /\ |
| |
GND------------------+---------+----- OSC GND
| _|_+
____/ ___
/ /\ |
| |
TRANS----------------+---------+------ OSC B-

Or, you could rig up a simple board with a 7812 and
a 7912 as a regulator.

The charger transformer was designed to provide enough
power to charge the batteries, and run the unit at the
same time.

-Chuck, WA3UQV

Paul Erickson wrote:
I have an HP204 with shot rechargable batteries. Has
anyone modified one of these to work just off of
the 120v mains? Looking for suggestions as to how
best to modify this thing.

cheers, Paul - VA7NT email:

Hi,
As far as I know, the battery-operated version requires batteries
to do the filtering, and contains only a charging circuit, not a
regulated power supply. I suppose you could duplicate the standard
supply, but it sounds like a lot of work. What I did (I have both the
AC and battery versions) was to attach some nicad packs outside the
case.

73, Alan

Hi,
As far as I know, the battery-operated version requires batteries
to do the filtering, and contains only a charging circuit, not a
regulated power supply. I suppose you could duplicate the standard
supply, but it sounds like a lot of work. What I did (I have both the
AC and battery versions) was to attach some nicad packs outside the
case.

73, Alan