Lowe HF225
 

I picked up yet another "perfectly working" Lowe receiver. This one would
howl for the first 5 minutes of operation, the FM detector didn't work for
this time because of low I.F. injections level, and system gain would be low
during this time.
I traced the problem to a 100uF lytic cap near the audio amp. After the unit
warmed up, I hit several components with freeze spray. After I found this
problem component, I removed it completely and the problem became much
worse. When I tacked a cap into the circuit to test my theory, the receiver
started working properly. The cap must have been leaky, because when I tried
to parellel another cap across this one, no change was noted.
This receiver uses the same audio amp as the HF150, so if you have a
receiver that howls even with an external speaker, this could be the
problem.
Between myself and some other friends, this is the 6th unit I have run into
that needs at least some kind of repair. It would seem that folks get scared
when these receivers start to malfunction, and "jump ship", so to speak.

Pete

Another thing I discovered.....................somebody had replaced the
blown 1st mixer with some sort of ECG substitute. As a result, the gain was
about 20dB lower than expected. I popped in the correct chip (SL6440C) and
the receiver is working quite well now. Sensitivity is very similar to the
HF-150, as is system gain. Lowe came out with a winner with this one.
If I get enough of these broken receivers, I may become a Lowe expert in
another 100 years.
Anyway, if anybody has some sort of problem with their receiver, feel free
to shout me down, using my e-mail address.

Pete

"Pete KE9OA" wrote in message
...
I picked up yet another "perfectly working" Lowe receiver. This one would
howl for the first 5 minutes of operation, the FM detector didn't work for
this time because of low I.F. injections level, and system gain would be
low during this time.
I traced the problem to a 100uF lytic cap near the audio amp. After the
unit warmed up, I hit several components with freeze spray. After I found
this problem component, I removed it completely and the problem became
much worse. When I tacked a cap into the circuit to test my theory, the
receiver started working properly. The cap must have been leaky, because
when I tried to parellel another cap across this one, no change was noted.
This receiver uses the same audio amp as the HF150, so if you have a
receiver that howls even with an external speaker, this could be the
problem.
Between myself and some other friends, this is the 6th unit I have run
into that needs at least some kind of repair. It would seem that folks get
scared when these receivers start to malfunction, and "jump ship", so to
speak.

Pete

Pete KE9OA wrote:

Another thing I discovered.....................somebody had replaced the
blown 1st mixer with some sort of ECG substitute. As a result, the gain was
about 20dB lower than expected. I popped in the correct chip (SL6440C) and
the receiver is working quite well now. Sensitivity is very similar to the
HF-150, as is system gain. Lowe came out with a winner with this one.
If I get enough of these broken receivers, I may become a Lowe expert in
another 100 years.
Anyway, if anybody has some sort of problem with their receiver, feel free
to shout me down, using my e-mail address.

Pete


Pete, if you ever run into a bad MC5800 hybrid RF/IF amp in a
receiver I have plenty.


--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

"Pete KE9OA" wrote in message
...
Another thing I discovered.....................somebody had replaced the
blown 1st mixer with some sort of ECG substitute. As a result, the gain
was about 20dB lower than expected. I popped in the correct chip (SL6440C)
and the receiver is working quite well now. Sensitivity is very similar to
the HF-150, as is system gain. Lowe came out with a winner with this one.
If I get enough of these broken receivers, I may become a Lowe expert in
another 100 years.
Anyway, if anybody has some sort of problem with their receiver, feel free
to shout me down, using my e-mail address.

Pete

"Pete KE9OA" wrote in message
...
I picked up yet another "perfectly working" Lowe receiver. This one would
howl for the first 5 minutes of operation, the FM detector didn't work for
this time because of low I.F. injections level, and system gain would be
low during this time.
I traced the problem to a 100uF lytic cap near the audio amp. After the
unit warmed up, I hit several components with freeze spray. After I found
this problem component, I removed it completely and the problem became
much worse. When I tacked a cap into the circuit to test my theory, the
receiver started working properly. The cap must have been leaky, because
when I tried to parellel another cap across this one, no change was
noted.
This receiver uses the same audio amp as the HF150, so if you have a
receiver that howls even with an external speaker, this could be the
problem.
Between myself and some other friends, this is the 6th unit I have run
into that needs at least some kind of repair. It would seem that folks
get scared when these receivers start to malfunction, and "jump ship", so
to speak.

Pete




Hi Pete

I wish I knew more about diagnosing and fixing radios myself. All I've done
is replace some pots and minor mods and installation of items. I'm handy
though as I build computers.Thanks for the offer.
I'm looking for a 225 for my collection so I'm on the lookout for them. I
almost bought one from the U.K. but it didn't look that hot in the picture
posted.

Good going fixing that 225 up. There's nothing better then taking a
perfectly workable radio and restoring it to it's former glory.

Lucky

Thanks Mike.........same thing goes if you ever need any TDA1572s. This is a
Philips AM Receiver on a chip.

Pete

"Michael A. Terrell" wrote in message
...
Pete KE9OA wrote:

Another thing I discovered.....................somebody had replaced the
blown 1st mixer with some sort of ECG substitute. As a result, the gain
was
about 20dB lower than expected. I popped in the correct chip (SL6440C)
and
the receiver is working quite well now. Sensitivity is very similar to
the
HF-150, as is system gain. Lowe came out with a winner with this one.
If I get enough of these broken receivers, I may become a Lowe expert in
another 100 years.
Anyway, if anybody has some sort of problem with their receiver, feel
free
to shout me down, using my e-mail address.

Pete


Pete, if you ever run into a bad MC5800 hybrid RF/IF amp in a
receiver I have plenty.


--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

Thanks Lucky! I'll let you know if I ever get bored with mine. As far as
repairing things, you are on the right track. It just takes time. Feel free
to shout me down directly if you ever have any radio questions.
About that HF225......the HF150 is better on MW if you use the Radio Shack
loop antenna into the high impedance input. I don't know if it is the way
that 12:1 transformer doesn't like the MW diplexer of if its ferrite core
material just isn't good on low frequencies. I did measure continuity, so
the RF transformer is good. On a long wire antenna, this receiver is great.
Measuring the sensitivity with an RF generator into the 50 ohm input, the
MDS is just under 0.1uV across the whole tuning range, which is the same as
the HF-150 when it has its whip preamplifier disengages.
A decent radio.

Pete

"Lucky" wrote in message
...

"Pete KE9OA" wrote in message
...
Another thing I discovered.....................somebody had replaced the
blown 1st mixer with some sort of ECG substitute. As a result, the gain
was about 20dB lower than expected. I popped in the correct chip
(SL6440C) and the receiver is working quite well now. Sensitivity is very
similar to the HF-150, as is system gain. Lowe came out with a winner
with this one.
If I get enough of these broken receivers, I may become a Lowe expert in
another 100 years.
Anyway, if anybody has some sort of problem with their receiver, feel
free to shout me down, using my e-mail address.

Pete

"Pete KE9OA" wrote in message
...
I picked up yet another "perfectly working" Lowe receiver. This one would
howl for the first 5 minutes of operation, the FM detector didn't work
for this time because of low I.F. injections level, and system gain would
be low during this time.
I traced the problem to a 100uF lytic cap near the audio amp. After the
unit warmed up, I hit several components with freeze spray. After I
found this problem component, I removed it completely and the problem
became much worse. When I tacked a cap into the circuit to test my
theory, the receiver started working properly. The cap must have been
leaky, because when I tried to parellel another cap across this one, no
change was noted.
This receiver uses the same audio amp as the HF150, so if you have a
receiver that howls even with an external speaker, this could be the
problem.
Between myself and some other friends, this is the 6th unit I have run
into that needs at least some kind of repair. It would seem that folks
get scared when these receivers start to malfunction, and "jump ship",
so to speak.

Pete




Hi Pete

I wish I knew more about diagnosing and fixing radios myself. All I've
done is replace some pots and minor mods and installation of items. I'm
handy though as I build computers.Thanks for the offer.
I'm looking for a 225 for my collection so I'm on the lookout for them. I
almost bought one from the U.K. but it didn't look that hot in the picture
posted.

Good going fixing that 225 up. There's nothing better then taking a
perfectly workable radio and restoring it to it's former glory.

Lucky

My Lowe HF-225 bacame dead on all bands but MW, keypad and frequency
display are working fine, cutoff point seems to be around 3000khz, not
certain anymore, but there is a definite cutoff point in there where it
just gets quiet, which leads me to suspect input filters, coils, or
other front-end circuits. This may have been result of lightning damage.
All other functions working OK. I have the service manual with
schematics and have done some work to this radio in the past. Can you
give me any leads? I really miss ths radio. Email welcome (no spam)

Thanks,

Bob from Mich

RM MS wrote:

My Lowe HF-225 bacame dead on all bands but MW, keypad and frequency
display are working fine, cutoff point seems to be around 3000khz, not
certain anymore, but there is a definite cutoff point in there where it
just gets quiet, which leads me to suspect input filters, coils, or
other front-end circuits. This may have been result of lightning damage.
All other functions working OK. I have the service manual with
schematics and have done some work to this radio in the past. Can you
give me any leads? I really miss ths radio. Email welcome (no spam)

Thanks,

Bob from Mich


I replied to your e-mail.

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida