HQ-145 sensitivity
 

Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after adjusting
the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc on
that band setting. I wonder if this was a design compromise? Or is there
still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would please
check whether theirs operates the same way. Just tune into WWV at 10 Mc
on both band settings and see if there's much difference in signal
strength. Thanks!

Tnx,
Joe K9LY

HQ-145 sensitivity
 

In article ,
"Joe L." wrote:

Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after adjusting
the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc on
that band setting. I wonder if this was a design compromise? Or is there
still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would please
check whether theirs operates the same way. Just tune into WWV at 10 Mc
on both band settings and see if there's much difference in signal
strength. Thanks!

Tnx,
Joe K9LY

Worse here on a working 145A. WWV 20-40db over 9 on the 4-10 range.
S3-S5 on the 10-30 range. Seems more sensitive at 30Mc than 10Mc here
too. However, I can't vouch for the alignment that a friend did 6 years
ago for me.

Please keep us posted.

Best,
Mike KM6WB

HQ-145 sensitivity
 

This is typical of many receivers. It is generally caused by variations
in local oscillator injection to the mixer. As you change the amount of
capacitance with the tuning capacitor, you change the amount of feedback
in the oscillator. Most oscillator circuits suffer from this.

73,
Darrell, WA5VGO



Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after
adjusting the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc
on that band setting. I wonder if this was a design compromise? Or is
there still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would
please check whether theirs operates the same way. Just tune into WWV
at 10 Mc on both band settings and see if there's much difference in
signal strength. Thanks!

Tnx,
Joe K9LY

HQ-145 sensitivity
 

On Apr 22, 3:05*pm, Darrell wrote:
This is typical of many receivers. It is generally caused by variations
in local oscillator injection to the mixer. As you change the amount of
capacitance with the tuning capacitor, you change the amount of feedback
in the oscillator. Most oscillator circuits suffer from this.

73,
Darrell, WA5VGO

Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after
adjusting the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc
on that band setting. I wonder if this was a design compromise? Or is
there still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would
please check whether theirs operates the same way. Just tune into WWV
at 10 Mc on both band settings and see if there's much difference in
signal strength. Thanks!

Tnx,
Joe K9LY

You are correct about the injection, but the HQ-145 did not suffer
from this, at least mine did not. Check the Oscillator injection -
you will probably find that it is down due to a bad component. Either
the tube is weak or you have a bad bypass cap. Also check the values
of all of the resistors with a meter.

Tim AA6DQ

HQ-145 sensitivity
 

On Apr 22, 1:40*pm, Mike wrote:
In article ,
*"Joe L." wrote:





Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after adjusting
the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc on
that band setting. I wonder if this was a design compromise? Or is there
still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would please
check whether theirs operates the same way. Just tune into WWV at 10 Mc
on both band settings and see if there's much difference in signal
strength. Thanks!

Tnx,
Joe K9LY

Worse here on a working 145A. WWV 20-40db over 9 on the 4-10 range.
S3-S5 on the 10-30 range. Seems more sensitive at *30Mc than 10Mc here
too. However, I can't vouch for the alignment that a friend did 6 years
ago for me.

Please keep us posted.

Best,
Mike KM6WB- Hide quoted text -

- Show quoted text -

My restored and aligned HQ-160 shows the same sort of difference on
the two bands. IIRC, the oscillator injection was similar on both
bands. Sounds like this is a generic problem with Hammarlunds of this
vintage.

Neil S.

HQ-145 sensitivity
 

Great answers, everyone. Thank you very much for all the input. I will
probably spend more time on it this weekend, and will report my findings
here.

Tnx & 73,
Joe K9LY


In article
,
nesesu wrote:


My restored and aligned HQ-160 shows the same sort of difference on
the two bands. IIRC, the oscillator injection was similar on both
bands. Sounds like this is a generic problem with Hammarlunds of this
vintage.

HQ-145 sensitivity
 

Hi Joe. My HQ-145 exhibits a very slight difference between the 10 Mcs
sensitivity on the 4-10 vs 10-30 Mcs bands. I spent a lot of time reworking
it last year and am very pleased with the result. Remember that the 10-30
band is double conversion an you should pay a lot of attention to the
adjustment of the 3035 Kc circuit. I ended up replacing T5 in mine because
someone had tried to repair the original and flowed some solder on the
bottom coil.

73 & Gud Luck!
K3PID
Ron H
--
This outgoing email was scanned by
Norton Antivirus Corp. Edition
and found to be virus free!

HQ-145 sensitivity
 

"Joe L." wrote in news:invalid-
:

I would appreciate it if someone else with a working HQ-145 would please
check whether theirs operates the same way. Just tune into WWV at 10 Mc
on both band settings and see if there's much difference in signal
strength. Thanks!



Joe, does the receiver hear the atmospheric noise in its most insensitive
spot? As long as the receiver can hear the natural noise level around it,
what difference does it make if it's sensitivity is 10uv or .01uv? The
answer is NONE. With all the racket on HF, a super-sensitive receiver is a
CURSE, not a feature. All the new radios are way too sensitive for HF with
their stupid S-meters showing S more than 1 with no signals. You end up
listening to racket and riding the AGC level control.

It's crazy....

--
-----
Larry
You can tell there's very intelligent life in the Universe
because none of them have ever tried to contact us.....

HQ-145 sensitivity
 

On Apr 22, 1:00*pm, "Joe L." wrote:
Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after adjusting
the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc on
that band setting. I wonder if this was a design compromise? Or is there
still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would please
check whether theirs operates the same way. Just tune into WWV at 10 Mc
on both band settings and see if there's much difference in signal
strength. Thanks!

Tnx,
Joe K9LY

I had one of these a while back. The first thing I noticed about the
HQ-145 is the lack of real electronic components within a huge
cabinet. There is plenty of real estate there! Some of the circuits
are pretty much bare bones and this includes the conversion/
oscillators. When the second conversion oscillator "Kicks In" it makes
up for the overall gain that was lacking on the lower band which was
single conversion. The HQ-180/160 didn't P-600 so I suspect they were
the top design and all the others just had stuff taken out to cut the
overall cost of the receiver. This radio was one step up from the
single conversion HQ-100 which suffered from image rejection problems
fixed by the double conversion of the HQ-145. I think the double
conversion setup was minimal and could have been more well thought out
to balance the gain a bit better.


Tony

HQ-145 sensitivity
 

On Apr 22, 1:00*pm, "Joe L." wrote:
Hello. I've been restoring a Hammarlund HQ-145 that has been neglected
for many years. After performing the RF alignment, I noticed that the
sensitivity at 10 Mc on the 10-30 Mc range is about 10 dB worse than
when tuned to 10 Mc on the 4-10 Mc range. This was even after adjusting
the 10-30 Mc ANT and RF coils as instructed by the manual.

The sensitivity is actually much better at 30 Mc than it is at 10 Mc on
that band setting. I wonder if this was a design compromise? Or is there
still something flaky with my HQ-145?

I would appreciate it if someone else with a working HQ-145 would please
check whether theirs operates the same way. Just tune into WWV at 10 Mc
on both band settings and see if there's much difference in signal
strength. Thanks!

Tnx,
Joe K9LY

I had one of these a while back. The first thing I noticed about the
HQ-145 is the lack of real electronic components within a huge
cabinet. There is plenty of real estate there! Some of the circuits
are pretty much bare bones and this includes the conversion/
oscillators. When the second conversion oscillator "Kicks In" it makes
up for the overall gain that was lacking on the lower band which was
single conversion. The HQ-180/160 didn't P-600 so I suspect they were
the top design and all the others just had stuff taken out to cut the
overall cost of the receiver. This radio was one step up from the
single conversion HQ-100 which suffered from image rejection problems
fixed by the double conversion of the HQ-145. I think the double
conversion setup was minimal and could have been more well thought out
to balance the gain a bit better.


Tony