I have an old HQ140x I bought non working and after replacing the filter
andvarious other caps and a couple tubes, its up and running. I realigned
the RF section to good effect but I'm suspicious the BFO isn't working quite
right. I've replaced the suspect looking caps in the BFO can with orange
drops and it works but it's a lot trickier tuning in SSB than on my HQ129x
and strong CW signals seem to overload it easily. Any ideas? Thanks.
Andy W1AWB

"Andy Bullington" wrote in message
...
I have an old HQ140x I bought non working and after replacing the filter
andvarious other caps and a couple tubes, its up and running. I realigned
the RF section to good effect but I'm suspicious the BFO isn't working
quite right. I've replaced the suspect looking caps in the BFO can with
orange drops and it works but it's a lot trickier tuning in SSB than on my
HQ129x and strong CW signals seem to overload it easily. Any ideas? Thanks.
Andy W1AWB
On older receivers, I often back down the RF gain control to prevent
overload on strong signals --
when using the BFO for SSB or CW reception. For those receivers that do not
have an RF Gain control, I use external attenuation.

gb

Very true.............with those old receivers that didn't have one of the
new types of product detectors, you had to run the unit with AGC off and use
back the RF gain down to eliminate the distortion. Newer receivers use a
mixer as an SSB detector.........the LO injection on these types of
detectors is run at about 10 times the expected level into the RF port. This
minimizes the distortion and allows the AGC to be run on these types of
signals.

Pete

"gb" wrote in message
...
"Andy Bullington" wrote in message
...
I have an old HQ140x I bought non working and after replacing the filter
andvarious other caps and a couple tubes, its up and running. I realigned
the RF section to good effect but I'm suspicious the BFO isn't working
quite right. I've replaced the suspect looking caps in the BFO can with
orange drops and it works but it's a lot trickier tuning in SSB than on my
HQ129x and strong CW signals seem to overload it easily. Any ideas?
Thanks.
Andy W1AWB
On older receivers, I often back down the RF gain control to prevent
overload on strong signals --
when using the BFO for SSB or CW reception. For those receivers that do
not have an RF Gain control, I use external attenuation.

gb

Pete KE9OA wrote:

Very true.............with those old receivers that didn't have one of the
new types of product detectors, you had to run the unit with AGC off and use
back the RF gain down to eliminate the distortion.


When did this commonplace knowledge disappear from the radio scene?
Pity...I guess thats why we have this forum.
-Bill

What I'm saying is there was something wrong in the BFO section. I KNOW to
back the RF gain down. Did you read my original post? Sorry if I wasn't
clear enough. Compared to my HQ 129x, a very similair radio, the SSB was
much trickier to tune in and CW signals were overloading much quicker.
Something was clearly wrong. Some people have e-mailed me off list with
ideas to increase the BFO injection slightly and everything is working fine
now. Thanks to all who helped.
Andy W1AWB

When did this commonplace knowledge disappear from the radio scene?
Pity...I guess thats why we have this forum.
-Bill

"When did this commonplace knowledge disappear from the radio scene?
Pity...I guess thats why we have this forum.
-Bill"

We all start out in radio knowing nothing. What we end up with is what we
learn from others, or figure out for ourselves.

I suppose I learned about different types of detectors and bfo injection
about 45 years ago - but I did not know it when I started. It still had to
be learned. And one thing I learned in graduate school was that usually the
person asking the most questions was the smartest.

Colin K7FM


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Bill M ) writes:
Pete KE9OA wrote:

Very true.............with those old receivers that didn't have one of the
new types of product detectors, you had to run the unit with AGC off and use
back the RF gain down to eliminate the distortion.


When did this commonplace knowledge disappear from the radio scene?
Pity...I guess thats why we have this forum.
-Bill

It disappeared when it became unneeded knowledge for most, ie when product
detectors came along and those using old receivers for SSB were in the
minority.

The best source of old knowledge is when something is new, because nobody
assumes everyone knows, and it's information people want. So the magazine
articles covered this really well when SSB first really hit in the late
forties, with complete and detailed articles, and then as SSB became more
common it was still out there but reduced to a paragraph or a sentence.
Since nothing has changed much, those early articles are still as useful
as back then.

WIth some things, say superregenerative receivers, it's like that game,
"broken telephone". By the time you get to the end, articles are not
repeating what was originally said, but what's been watered down in decades
of rather simple articles.

Of course, the original poster has said there was a problem beyond this
matter, and indeed there was something in the wording that made me think
it wasn't this issue.

Michael VE2BVW

Andy Bullington wrote:

What I'm saying is there was something wrong in the BFO section. I KNOW to
back the RF gain down.

Ok, sorry, I got the impression from one post that turning the gain
down was supposedly a "fix".

-Bill