On 11.07.2015 19:43, Cursitor Doom wrote:
On Sat, 11 Jul 2015 10:10:40 -0400, Pat wrote:

Some supplies will not regulate voltage without a load. Try
measuring it again with a small load (eg, a 1K resistor) across
the supply.

Good point! Still doesn't check-out, though. Rated current at 12V is
500mA, so a 50 Ohm resistor would be more appropriate. Managed to
find a 47R power resistor and connected across supply. Now reading
14.45V, so deffo not right...

AOR Japan - that supply is for a radio, right?

That reminds me of the (maybe similar) power supply of another radio.
Last year I bought a Yupiteru MVT-7500. It's a small handheld radio
with a 100 kHz to 1.3 GHz continuous frequency range, operable from
either 3 AA cells or an external power supply. It came with a linear
PSU, rated for a 100 V AC mains input (Japanese) and a 12V DC output.

At least, 12V DC is what's printed on it. Since I don't have a 100 V
mains socket at home, I couldn't test it right away - had to get a
230 to 2x48 V transformer first, and use the secondaries in series
(96 V nominal) as a practical approximation. Unloaded it happens to
be slightly over 100 V, but should be within usual tolerances. When
I plugged the Yupi's power supply into it and checked the output with
a multimeter (unloaded), it went up over 17 V! At first I thought my
improvised primary supply was iffy, but nope, the primary was OK.

Then I tried loading it and it just barely got near its rated output
under maximum rated load of 200 mA. But since the radio never really
uses the full 200 mA anyway - either 80 or 150 mA depending on the
state of the LCD backlight - the power supply voltage is much higher.
It seems to run at just over 15 V, more or less, under "real life"
conditions and never gets down to 12 V with the radio as a load.

Apparently here the PSU has just a transformer, a bridge rectifier
and a cap - nothing else, all the regulation is done in the radio.

Yours may be similar. Btw, was yours also rated for 100 V and did
you plug it into 115 V by any chance? If so, consider getting it a
"properly" rated supply. The Japanese have a 100 V mains, so when
they write 100 V, they actually mean it. Using the PSU on 115 V
may work, but it could likely stress components in the radio if
connected like this for a significant period of time.

Regards
Dimitrij