It turned out to be Q4 (MC14569) that had a thermal problem. Lowe UK was
nice enough to steer me in the right direction. After the unit was on for
about 15 minutes the problem would surface. I cooled the suspected device
and the problem went away. After 2 more minutes, the problem returned; once
again, I cooled Q4 and normal operation was resumed.
Actually, it is pretty interesting how the BFO signal is derived. The
reference oscillator is divided down by different intervals to derived the
USB/LSB injection frequencies. A ceramic ladder filter is used to filter the
rich harmonics from the 4569 and so that only the ones in the 455kHz range
are selected.
It is interesting how the 44.545MHz signal is derived. A fundamental
oscillator in the 14MHz range is used with a quad diode array to generate
the harmonics. An LC tank circuit selects the 44.545MHz harmonic. Pretty
cool design.
On a final note.....................a nice fellow on the other side of the
pond was nice enough to scan the service manual for this receiver and send
it to me in 4 PDF files. I am going to contact Lowe UK and see if it is ok
to post the manual up on mods.dk
Maybe, I will zip the file down to make it easier to e-mail to folks who
want it now.

Pete

"Telamon" wrote in message
...
If you have a warmup problem it could be a power supply voltage
regulator. Some change the regulated voltage if they get to hot and the
circuits they power shift with the voltage. Simple things first.

In article ,
"Pete KE9OA" wrote:

I agree................I have both the AOR7030 and the Lowe HF-150.
Although
the 7030 is good, the HF-150 does have higher overall gain. I think this
is
because they are using the full capabilities of the SL6700 I.F.
demodulator
chip, while in the 7030, AOR is only using the I.F. amplifier/demodulator
portion of a TDA1572 chip. The 1572 is a very good device, but it helps
when
you use the on-board RF amp and the on-board mixer.
I am using the 1572 in my MW receiver and the receiver has that same type
of
high gain that the HF-150 has.
Now, if I could only figure out the SSB problem with my '150. It works
fine
for the first 15 minutes, but after that time the oscillator seems to
skew.
It appears to be the 4094 shift register/DAC that has the problem. Once I
figure things out, I will post my findings to the NG.
I guess I can use it in AM mode for the time
being...............................

Pete

"Dale Parfitt" wrote in message
news:LxPWd.63914$uc.1617@trnddc08...


As much as I love the HF-150, I don't think it's in the same league as
the 7030+. The 7030+ offers many more features, greater dynamic range,
more filter choices, etc.

Steve

I think you're right Steve- I have owned both. But I sold the 7030 and
still
have the Lowe. As you say, it is wonderfully built, easy to use and
highly
portable. I have never overloaded mine.
Once backlit, a fabulous bedside RX.

Dale W4OP



--
Telamon
Ventura, California