rkhalona wrote:

I also have an HF-225 (mine is the Europa version) and looked into this
a while back; I have not found an acceptable solution short of a
Miracle Whip antenna (a tunable 56" whip), which is expensive.

RK

Well, I guess I could rip the whip off my Satellit 800...

(kidding!)

There are wall warts that don't use a transformer to step down the
voltage??

Seems to me the only way to tell whether the output is regulated and
bypassed is to check the voltage with varying loads and 'scope the
output for noise.

I'm starting to think it would be easier just to get one of those
little Radio Shack 2 or 3 amp power supplies for $15 or $20 new or at a
hamfest for $5.

Yike, $25 for a whip plus shipping! But I might do it.

Yike, $25 for a whip plus shipping! But I might do it.

The hum is due to a flaw in the audio output circuit design. Plug in
an external speaker and it will go away. There's a resistor (R134 or
139 - can't read the lousy schematic, but it's connected to J7) you can
bypass (short out), and the hum in the internal speaker will be gone
completely with an unregulated wallwart. No one has been able to figure
out what the original Lowe designer was attempting to do with this
circuit by connecting the internal speaker capacitively to the B+ rail
instead of ground (which is what the external speaker connects to when
plugged in.

Frank
K3YAZ

By the way the resistor is a 1K, 1 watt.

Frank

Avery W3AVE wrote:

Yup, I realized that's all I need to do when I saw a photo of the rear.
But I think I'll pull out one of my old Weller guns. More authentic for
a job like this.


I remember flattening the centre of a bit of 14 guage solid wire for a
home made replacement tip on those things.The gun was handy for one or
two solder joints, but after that,soon became a pain.

I've preferred the pencil type ever since. I've found around thirty five
watts works for everything I do...well, not EVERYTHING, but a propane
torch handles those jobs.


mike

ah.

Anyway, back to the whip. The amp and whip form an active antenna which
works pretty well. You won't get nearly the sensitivity off the same whip
connected to the 50 ohm input of the radio. But it sounds like you might
not be using it that way anyway.

Lowe will sell the whip amp for the HF250, which can be adapted to the
HF225. You'll have to find someone outside of the US to buy it and send it
to you, though.

How about the sync detector? Did your HF225 come with that?
John

"Avery W3AVE" wrote in message
oups.com...

John Black wrote:
The Radio Shack supply would work fine. I don't think there was ever
an
original 120v Lowe supply; every one I've seen was 220v.

There was. I had the Europa version of the radio, which I bought new in
the '90s (I never should have sold it) and which came with a 120V wall
wart.

John Black wrote:
ah.

Anyway, back to the whip. The amp and whip form an active antenna which
works pretty well. You won't get nearly the sensitivity off the same whip
connected to the 50 ohm input of the radio. But it sounds like you might
not be using it that way anyway.

I will, in fact.

Lowe will sell the whip amp for the HF250, which can be adapted to the
HF225. You'll have to find someone outside of the US to buy it and send it
to you, though.

I saw that Lowe has instructions for adapting the 250 amp to the 225,
and I'd be interested in doing that...but I'll have to find somebody in
the U.K.

How about the sync detector? Did your HF225 come with that?
John

Yes. It's a Europa, so the FM/AM sync option came standard. Or if it
didn't, it was installed.

wrote:
The hum is due to a flaw in the audio output circuit design. Plug in
an external speaker and it will go away. There's a resistor (R134 or
139 - can't read the lousy schematic, but it's connected to J7) you can
bypass (short out), and the hum in the internal speaker will be gone
completely with an unregulated wallwart. No one has been able to figure
out what the original Lowe designer was attempting to do with this
circuit by connecting the internal speaker capacitively to the B+ rail
instead of ground (which is what the external speaker connects to when
plugged in.

Frank
K3YAZ

Frank,

Great information, since I've got a boxful of wall warts and wasn't
looking forward to testing them one by one for regulation. Is this fix
endorsed, or at least acknowledged, by Lowe?