On Jan 23, 2:09*pm, Kevin Alfred Strom
wrote:
bpnjensen wrote:

[...]



The radio in question, BTW, is a simple DX-160 - it's front end is
pretty wide open anyway, but heck, why not? *As long as I don't send a
big static charge through it, I figure I cannot do much damage :-)

BJ

I had a DX-150A in the early 1970s, and if I recall correctly, it
had an "antenna trim" control to peak up the input network for
maximum signal. The DX-160 may be the same -- the differences were
minimal, as I remember.

The trim adjustment would help match varying impedances to some
extent, but there could be cases where an input transformer would
help even more -- with a random impedance antenna on a wide range of
frequencies, it's hard to predict without making measurements.

Transformers work both ways, so one could add a switch for 1)
impedance step-up, 2) impedance step-down, and 3) direct connection.
Of course, an antenna coupler is another possible way to approach
the impedance issue.

With all good wishes,

Kevin, WB4AIO.
--http://kevinalfredstrom.com/

Mssrs. Maus and Strom, thank you! I think I will concoct a device
soon to see what happens with it.

Bruce Jensen

On Jan 23, 11:00*pm, bpnjensen wrote:
On Jan 23, 2:09*pm, Kevin Alfred Strom
wrote:





bpnjensen wrote:

[...]

The radio in question, BTW, is a simple DX-160 - it's front end is
pretty wide open anyway, but heck, why not? *As long as I don't send a
big static charge through it, I figure I cannot do much damage :-)

BJ

I had a DX-150A in the early 1970s, and if I recall correctly, it
had an "antenna trim" control to peak up the input network for
maximum signal. The DX-160 may be the same -- the differences were
minimal, as I remember.

The trim adjustment would help match varying impedances to some
extent, but there could be cases where an input transformer would
help even more -- with a random impedance antenna on a wide range of
frequencies, it's hard to predict without making measurements.

Transformers work both ways, so one could add a switch for 1)
impedance step-up, 2) impedance step-down, and 3) direct connection.
Of course, an antenna coupler is another possible way to approach
the impedance issue.

With all good wishes,

Kevin, WB4AIO.
--http://kevinalfredstrom.com/

Mssrs. Maus and Strom, thank you! *I think I will concoct a device
soon to see what happens with it.

Bruce Jensen

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

Again, my sincere thanks for the advice...

Bruce Jensen

bpnjensen wrote:
[...]
Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?




The latter course seems best to me, since the ideal core
characteristics are likely different for the two purposes.



Again, my sincere thanks for the advice...

Bruce Jensen



You're welcome; have fun with the DX-160.


With all good wishes,




Kevin, WB4AIO.
--
http://kevinalfredstrom.com/

On 1/24/10 11:55 , bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?


Without specifics on the nature of your RFI, I'd build the
transformer from the recommended materials, 43 or 77, and then build
frequency specific chokes to purpose. That way, if your RFI changes,
as it often can, you're solution is to built another choke, not to
revise your receiver's input.

Kevin makes a good point about the antenna trim control at the
input of DX-160. That covers a multitude of sins. Not unlike my
Nationals, similarly equipped.

That control showed up on DX-120, and was the reason I got
interested in this line in the first place. I couldn't afford one
until DX-150. Bought one of those, and have had two DX-160s since.
Fun radios. Not quite as selective as my S-40 and S-53 Halli's but
good for program listening on the big guys. DX-160 had less hum in
the audio, and came on immediately. After more than a decade of
tubes, by that time, I thought that was bitchin' cool. Just couldn't
justify the money at the time.

DX-160 has pretty lifeless audio. Not much above 6k, and bottom
rolled of below 150hz. You can bring a little life back to that
bottom end, by changing a couple of the capacitors. One in the audio
circuit, and one bringing the audio from the detector to the audio
stage. Which ones at this point, specifically, I don't recall, but I
think one is on a trace on the extreme right of the PCB. It's out
there by itself, easy to replace. The other is further inboard, near
the audio IC. But you can cut-and-try with a .5ufd or a .1 ufd film,
across the any of the likely candidates listening for a change. Can
make quite a difference. Although with the fact AGC, and the
generally poor audio stage, don't expect Little Jewel audio.

You can clean up the woolly audio by replacing all the ceramic
capacitors on the board with films. Better definition and clarity.
Small films will fit right in the ceramic positions, and by
selecting your components carefully, for things like thermal
coefficient, you can mitigate some of the drift. Not all, but some.

And DX-160 will drift.

Further cleaning can be achieved by replacing the electrolytics.
Not only in the power supply, but those dispersed throughout the
board. After all these years, some will have become, or have begun
to become unformed. Some my be distended, indicating impending
failure. Some may even leak. Simple replacement procedure.

Touching up the alignment will also help, and using WWV as a
frequency standard, you can do a creditable job calibrating dial
positions.

Lastly, the dial lights have decent, but not remarkably long
life. You can find drop-in LED replacements at Digi-Key, or
SuperbrightLeds.com. The warm whites look just like incandescents,
and last 100 times longer. You may have to add a small series
resistor to the dial light circuit to limit current to the LED
replacements. That's a small matter, and dramatically improves life
of the lamp without significantly altering lumen output.

Now, if you REALLY want to make this rig over, you can install
Murata filters in the IF's. But that may be a long reach for such a
simple receiver.





p

On Jan 25, 6:27*am, "D. Peter Maus"
wrote:
On 1/24/10 11:55 , bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. *Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

* *Without specifics on the nature of your RFI, I'd build the
transformer from the recommended materials, 43 or 77, and then build
frequency specific chokes to purpose. That way, if your RFI changes,
as it often can, you're solution is to built another choke, not to
revise your receiver's input.

* *Kevin makes a good point about the antenna trim control at the
input of DX-160. That covers a multitude of sins. Not unlike my
Nationals, similarly equipped.

* *That control showed up on DX-120, and was the reason I got
interested in this line in the first place. I couldn't afford one
until DX-150. Bought one of those, and have had two DX-160s since.
Fun radios. Not quite as selective as my S-40 and S-53 Halli's but
good for program listening on the big guys. DX-160 had less hum in
the audio, and came on immediately. After more than a decade of
tubes, by that time, I thought that was bitchin' cool. Just couldn't
justify the money at the time.

* *DX-160 has pretty lifeless audio. Not much above 6k, and bottom
rolled of below 150hz. You can bring a little life back to that
bottom end, by changing a couple of the capacitors. One in the audio
circuit, and one bringing the audio from the detector to the audio
stage. Which ones at this point, specifically, I don't recall, but I
think one is on a trace on the extreme right of the PCB. It's out
there by itself, easy to replace. The other is further inboard, near
the audio IC. But you can cut-and-try with a .5ufd or a .1 ufd film,
across the any of the likely candidates listening for a change. Can
make quite a difference. Although with the fact AGC, and the
generally poor audio stage, don't expect Little Jewel audio.

* *You can clean up the woolly audio by replacing all the ceramic
capacitors on the board with films. Better definition and clarity.
Small films will fit right in the ceramic positions, and by
selecting your components carefully, for things like thermal
coefficient, you can mitigate some of the drift. Not all, but some.

* *And DX-160 will drift.

* *Further cleaning can be achieved by replacing the electrolytics.
Not only in the power supply, but those dispersed throughout the
board. After all these years, some will have become, or have begun
to become unformed. Some my be distended, indicating impending
failure. Some may even leak. Simple replacement procedure.

* *Touching up the alignment will also help, and using WWV as a
frequency standard, you can do a creditable job calibrating dial
positions.

* *Lastly, the dial lights have decent, but not remarkably long
life. You can find drop-in LED replacements at Digi-Key, or
SuperbrightLeds.com. The warm whites look just like incandescents,
and last 100 times longer. You may have to add a small series
resistor to the dial light circuit to limit current to the LED
replacements. That's a small matter, and dramatically improves life
of the lamp without significantly altering lumen output.

* *Now, if you REALLY want to make this rig over, you can install
Murata filters in the IF's. But that may be a long reach for such a
simple receiver.

* *p

Thank you once again, Peter and Kevin - great stuff! My 160 does need
freq calibration pretty badly, and possibly (probably?) alignment as
well.

Bruce

On Jan 25, 4:05*pm, bpnjensen wrote:
On Jan 25, 6:27*am, "D. Peter Maus"
wrote:





On 1/24/10 11:55 , bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. *Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

* *Without specifics on the nature of your RFI, I'd build the
transformer from the recommended materials, 43 or 77, and then build
frequency specific chokes to purpose. That way, if your RFI changes,
as it often can, you're solution is to built another choke, not to
revise your receiver's input.

* *Kevin makes a good point about the antenna trim control at the
input of DX-160. That covers a multitude of sins. Not unlike my
Nationals, similarly equipped.

* *That control showed up on DX-120, and was the reason I got
interested in this line in the first place. I couldn't afford one
until DX-150. Bought one of those, and have had two DX-160s since.
Fun radios. Not quite as selective as my S-40 and S-53 Halli's but
good for program listening on the big guys. DX-160 had less hum in
the audio, and came on immediately. After more than a decade of
tubes, by that time, I thought that was bitchin' cool. Just couldn't
justify the money at the time.

* *DX-160 has pretty lifeless audio. Not much above 6k, and bottom
rolled of below 150hz. You can bring a little life back to that
bottom end, by changing a couple of the capacitors. One in the audio
circuit, and one bringing the audio from the detector to the audio
stage. Which ones at this point, specifically, I don't recall, but I
think one is on a trace on the extreme right of the PCB. It's out
there by itself, easy to replace. The other is further inboard, near
the audio IC. But you can cut-and-try with a .5ufd or a .1 ufd film,
across the any of the likely candidates listening for a change. Can
make quite a difference. Although with the fact AGC, and the
generally poor audio stage, don't expect Little Jewel audio.

* *You can clean up the woolly audio by replacing all the ceramic
capacitors on the board with films. Better definition and clarity.
Small films will fit right in the ceramic positions, and by
selecting your components carefully, for things like thermal
coefficient, you can mitigate some of the drift. Not all, but some.

* *And DX-160 will drift.

* *Further cleaning can be achieved by replacing the electrolytics.
Not only in the power supply, but those dispersed throughout the
board. After all these years, some will have become, or have begun
to become unformed. Some my be distended, indicating impending
failure. Some may even leak. Simple replacement procedure.

* *Touching up the alignment will also help, and using WWV as a
frequency standard, you can do a creditable job calibrating dial
positions.

* *Lastly, the dial lights have decent, but not remarkably long
life. You can find drop-in LED replacements at Digi-Key, or
SuperbrightLeds.com. The warm whites look just like incandescents,
and last 100 times longer. You may have to add a small series
resistor to the dial light circuit to limit current to the LED
replacements. That's a small matter, and dramatically improves life
of the lamp without significantly altering lumen output.

* *Now, if you REALLY want to make this rig over, you can install
Murata filters in the IF's. But that may be a long reach for such a
simple receiver.

* *p

Thank you once again, Peter and Kevin - great stuff! *My 160 does need
freq calibration pretty badly, and possibly (probably?) alignment as
well.

Bruce- Hide quoted text -

- Show quoted text -
After changing just 2 or 3 ceramics in the audio stages has
improved enormously in my DX-160. Drift is somewhat moderate, compared
to other radios of similar design and era. But, the band switch is
VERY troublesome. Really kills gain and sometimes creates other
problems as well (requires incessant care,like a newborn). On the
positive note: the IF filter is actually of mechanical type,built
right into the IF coil ! Calibration is an over statement in this
receiver- it was never designed to be a precision gadjet,alas. Even
the model which preceded it , the SX/AX- 190 was miles ahead of it in
most respects. Radio Shack has been lowering it's standards
ever since...

On Jan 26, 1:54*am, wrote:
On Jan 25, 4:05*pm, bpnjensen wrote:



On Jan 25, 6:27*am, "D. Peter Maus"
wrote:

On 1/24/10 11:55 , bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. *Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

* *Without specifics on the nature of your RFI, I'd build the
transformer from the recommended materials, 43 or 77, and then build
frequency specific chokes to purpose. That way, if your RFI changes,
as it often can, you're solution is to built another choke, not to
revise your receiver's input.

* *Kevin makes a good point about the antenna trim control at the
input of DX-160. That covers a multitude of sins. Not unlike my
Nationals, similarly equipped.

* *That control showed up on DX-120, and was the reason I got
interested in this line in the first place. I couldn't afford one
until DX-150. Bought one of those, and have had two DX-160s since.
Fun radios. Not quite as selective as my S-40 and S-53 Halli's but
good for program listening on the big guys. DX-160 had less hum in
the audio, and came on immediately. After more than a decade of
tubes, by that time, I thought that was bitchin' cool. Just couldn't
justify the money at the time.

* *DX-160 has pretty lifeless audio. Not much above 6k, and bottom
rolled of below 150hz. You can bring a little life back to that
bottom end, by changing a couple of the capacitors. One in the audio
circuit, and one bringing the audio from the detector to the audio
stage. Which ones at this point, specifically, I don't recall, but I
think one is on a trace on the extreme right of the PCB. It's out
there by itself, easy to replace. The other is further inboard, near
the audio IC. But you can cut-and-try with a .5ufd or a .1 ufd film,
across the any of the likely candidates listening for a change. Can
make quite a difference. Although with the fact AGC, and the
generally poor audio stage, don't expect Little Jewel audio.

* *You can clean up the woolly audio by replacing all the ceramic
capacitors on the board with films. Better definition and clarity.
Small films will fit right in the ceramic positions, and by
selecting your components carefully, for things like thermal
coefficient, you can mitigate some of the drift. Not all, but some.

* *And DX-160 will drift.

* *Further cleaning can be achieved by replacing the electrolytics.
Not only in the power supply, but those dispersed throughout the
board. After all these years, some will have become, or have begun
to become unformed. Some my be distended, indicating impending
failure. Some may even leak. Simple replacement procedure.

* *Touching up the alignment will also help, and using WWV as a
frequency standard, you can do a creditable job calibrating dial
positions.

* *Lastly, the dial lights have decent, but not remarkably long
life. You can find drop-in LED replacements at Digi-Key, or
SuperbrightLeds.com. The warm whites look just like incandescents,
and last 100 times longer. You may have to add a small series
resistor to the dial light circuit to limit current to the LED
replacements. That's a small matter, and dramatically improves life
of the lamp without significantly altering lumen output.

* *Now, if you REALLY want to make this rig over, you can install
Murata filters in the IF's. But that may be a long reach for such a
simple receiver.

* *p

Thank you once again, Peter and Kevin - great stuff! *My 160 does need
freq calibration pretty badly, and possibly (probably?) alignment as
well.

Bruce- Hide quoted text -

- Show quoted text -

* * * * * *After changing just 2 or 3 ceramics in the audio stages has
improved enormously in my DX-160. Drift is somewhat moderate, compared
to other radios of similar design and era. But, the band switch is
VERY troublesome. Really kills gain and sometimes creates other
problems as well (requires incessant care,like a newborn). On the
positive note: the IF filter is actually of mechanical type,built
right into the IF coil ! *Calibration is an over statement in this
receiver- it was never designed to be a precision gadjet,alas. *Even
the model which preceded it , the SX/AX- 190 was miles ahead of it in
most respects. * * * * *Radio Shack has been lowering it's standards
ever since...- Hide quoted text -

- Show quoted text -

Hi, Anthony - when you changed the ceramics, did you change the values
too or just a like-for-like replacement with films?

My DX-160 freqs are so far off that it needs SOMETHING... :-O Band 3
is a disaster; 2 is quite good, 4 is pretty far off but usable, 5 is
not great. Band 1 is so full of intermod products as to be useless
anyway...

How does the bandswitch kill gain? I have pretty good sensitivity on
all of the bands (sometimes too much!)...

Bruce

On 1/26/10 10:08 , bpnjensen wrote:
My DX-160 freqs are so far off that it needs SOMETHING... :-O Band 3
is a disaster; 2 is quite good, 4 is pretty far off but usable, 5 is
not great. Band 1 is so full of intermod products as to be useless
anyway...




That's about normal for DX-160 at this age. And it will be prone
to intermod. The RF gain control is before the first gain stage, so
just turn it down until the intermod products start to decrease. Or
reduce the amount of antenna. A good ground will help, too.

Dial calibration is usually adjusted with LO for each band. The
upper bands will be further out of tolerance due to the greater
sensitivity to component value drift at higher frequencies.

Of course, if the bands are significantly out, you can well
assume with some certainty that the IF's are also out. Though likely
not by too much.

The bandswitch can be kind of flaky. Can spray cleaning may not
have the desired results. If you want to go bat**** crazy with this,
GoldPoint makes a really nice, configurable-to-purpose Swiss made
switch that can be applied to replace the flaky factory switch.
You'll never have bandswitch problems again. Cost more more than the
radio. More than a couple of them, actually, but anything worth
doing is worth overdoing.

They also make some detented step switch rotary faders for audio
(I put one in my C-26 preamp) they're amazing. But also not cheap.

I found the manual with schematic for mine. I can have a copy
made for you, if you need it.

p

On Jan 26, 11:08*am, bpnjensen wrote:
On Jan 26, 1:54*am, wrote:





On Jan 25, 4:05*pm, bpnjensen wrote:

On Jan 25, 6:27*am, "D. Peter Maus"
wrote:

On 1/24/10 11:55 , bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. *Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

* *Without specifics on the nature of your RFI, I'd build the
transformer from the recommended materials, 43 or 77, and then build
frequency specific chokes to purpose. That way, if your RFI changes,
as it often can, you're solution is to built another choke, not to
revise your receiver's input.

* *Kevin makes a good point about the antenna trim control at the
input of DX-160. That covers a multitude of sins. Not unlike my
Nationals, similarly equipped.

* *That control showed up on DX-120, and was the reason I got
interested in this line in the first place. I couldn't afford one
until DX-150. Bought one of those, and have had two DX-160s since.
Fun radios. Not quite as selective as my S-40 and S-53 Halli's but
good for program listening on the big guys. DX-160 had less hum in
the audio, and came on immediately. After more than a decade of
tubes, by that time, I thought that was bitchin' cool. Just couldn't
justify the money at the time.

* *DX-160 has pretty lifeless audio. Not much above 6k, and bottom
rolled of below 150hz. You can bring a little life back to that
bottom end, by changing a couple of the capacitors. One in the audio
circuit, and one bringing the audio from the detector to the audio
stage. Which ones at this point, specifically, I don't recall, but I
think one is on a trace on the extreme right of the PCB. It's out
there by itself, easy to replace. The other is further inboard, near
the audio IC. But you can cut-and-try with a .5ufd or a .1 ufd film,
across the any of the likely candidates listening for a change. Can
make quite a difference. Although with the fact AGC, and the
generally poor audio stage, don't expect Little Jewel audio.

* *You can clean up the woolly audio by replacing all the ceramic
capacitors on the board with films. Better definition and clarity.
Small films will fit right in the ceramic positions, and by
selecting your components carefully, for things like thermal
coefficient, you can mitigate some of the drift. Not all, but some.

* *And DX-160 will drift.

* *Further cleaning can be achieved by replacing the electrolytics.
Not only in the power supply, but those dispersed throughout the
board. After all these years, some will have become, or have begun
to become unformed. Some my be distended, indicating impending
failure. Some may even leak. Simple replacement procedure.

* *Touching up the alignment will also help, and using WWV as a
frequency standard, you can do a creditable job calibrating dial
positions.

* *Lastly, the dial lights have decent, but not remarkably long
life. You can find drop-in LED replacements at Digi-Key, or
SuperbrightLeds.com. The warm whites look just like incandescents,
and last 100 times longer. You may have to add a small series
resistor to the dial light circuit to limit current to the LED
replacements. That's a small matter, and dramatically improves life
of the lamp without significantly altering lumen output.

* *Now, if you REALLY want to make this rig over, you can install
Murata filters in the IF's. But that may be a long reach for such a
simple receiver.

* *p

Thank you once again, Peter and Kevin - great stuff! *My 160 does need
freq calibration pretty badly, and possibly (probably?) alignment as
well.

Bruce- Hide quoted text -

- Show quoted text -

* * * * * *After changing just 2 or 3 ceramics in the audio stages has
improved enormously in my DX-160. Drift is somewhat moderate, compared
to other radios of similar design and era. But, the band switch is
VERY troublesome. Really kills gain and sometimes creates other
problems as well (requires incessant care,like a newborn). On the
positive note: the IF filter is actually of mechanical type,built
right into the IF coil ! *Calibration is an over statement in this
receiver- it was never designed to be a precision gadjet,alas. *Even
the model which preceded it , the SX/AX- 190 was miles ahead of it in
most respects. * * * * *Radio Shack has been lowering it's standards
ever since...- Hide quoted text -

- Show quoted text -

Hi, Anthony - when you changed the ceramics, did you change the values
too or just a like-for-like replacement with films?

My DX-160 freqs are so far off that it needs SOMETHING... :-O *Band 3
is a disaster; 2 is quite good, 4 is pretty far off but usable, 5 is
not great. *Band 1 is so full of intermod products as to be useless
anyway...

How does the bandswitch kill gain? *I have pretty good sensitivity on
all of the bands (sometimes too much!)...

Bruce- Hide quoted text -

- Show quoted text -

Arthur , not Anthony is the name here. Made some audio changes
several years ago according to www.mods.dk (excellent site, by the
way). If I remember correctly, it was C58 0.1uF became 5uF
(electrolytic) and C62 0.001 became 100pF. Audio became listenable at
this stage and I was never interested in making an eagle out of this
turkey. Stability is an old problem with most analog radios,whether
tubed or solid state ! Power supply, mixer/oscillator, variable
capacitors as well as regular component drift- all of these will
reflect in short/long term drift. The worst offender ,in my opinion is
S350 purchased from RShack. Under a Grundig label it was really a
Tecsun made portable. Never in my life did I see such abnormal drift!
Had something to do with temperature since it would get really freaky
in the summertime, especially pronounced at the higher HF frequencies.
DX-160's problems are nowhere near this bad. Oh, about that GoldPoint
bandswitch,Peter. What material is it made of ? If it has silver
contacts,then it is a real switch.

On Jan 26, 1:54*am, wrote:
On Jan 25, 4:05*pm, bpnjensen wrote:



On Jan 25, 6:27*am, "D. Peter Maus"
wrote:

On 1/24/10 11:55 , bpnjensen wrote:

Another question on this subject - what core should be used for this
application?

Amidon, among others, has cores of many materials including 43 and 77,
both of which seem to get use in these applications; however, for RFI
problems below 10 MHz, Amidon recommends cores of J material, and my
RFI problems (while not confined to under 10 MHz) are primarily below
that frequency. *Would use of J material be wise here, or for this
matching transformer would I be better using the old standbys 43 or
77, and then making lots of separate chokes from other materials such
as J?

* *Without specifics on the nature of your RFI, I'd build the
transformer from the recommended materials, 43 or 77, and then build
frequency specific chokes to purpose. That way, if your RFI changes,
as it often can, you're solution is to built another choke, not to
revise your receiver's input.

* *Kevin makes a good point about the antenna trim control at the
input of DX-160. That covers a multitude of sins. Not unlike my
Nationals, similarly equipped.

* *That control showed up on DX-120, and was the reason I got
interested in this line in the first place. I couldn't afford one
until DX-150. Bought one of those, and have had two DX-160s since.
Fun radios. Not quite as selective as my S-40 and S-53 Halli's but
good for program listening on the big guys. DX-160 had less hum in
the audio, and came on immediately. After more than a decade of
tubes, by that time, I thought that was bitchin' cool. Just couldn't
justify the money at the time.

* *DX-160 has pretty lifeless audio. Not much above 6k, and bottom
rolled of below 150hz. You can bring a little life back to that
bottom end, by changing a couple of the capacitors. One in the audio
circuit, and one bringing the audio from the detector to the audio
stage. Which ones at this point, specifically, I don't recall, but I
think one is on a trace on the extreme right of the PCB. It's out
there by itself, easy to replace. The other is further inboard, near
the audio IC. But you can cut-and-try with a .5ufd or a .1 ufd film,
across the any of the likely candidates listening for a change. Can
make quite a difference. Although with the fact AGC, and the
generally poor audio stage, don't expect Little Jewel audio.

* *You can clean up the woolly audio by replacing all the ceramic
capacitors on the board with films. Better definition and clarity.
Small films will fit right in the ceramic positions, and by
selecting your components carefully, for things like thermal
coefficient, you can mitigate some of the drift. Not all, but some.

* *And DX-160 will drift.

* *Further cleaning can be achieved by replacing the electrolytics.
Not only in the power supply, but those dispersed throughout the
board. After all these years, some will have become, or have begun
to become unformed. Some my be distended, indicating impending
failure. Some may even leak. Simple replacement procedure.

* *Touching up the alignment will also help, and using WWV as a
frequency standard, you can do a creditable job calibrating dial
positions.

* *Lastly, the dial lights have decent, but not remarkably long
life. You can find drop-in LED replacements at Digi-Key, or
SuperbrightLeds.com. The warm whites look just like incandescents,
and last 100 times longer. You may have to add a small series
resistor to the dial light circuit to limit current to the LED
replacements. That's a small matter, and dramatically improves life
of the lamp without significantly altering lumen output.

* *Now, if you REALLY want to make this rig over, you can install
Murata filters in the IF's. But that may be a long reach for such a
simple receiver.

* *p

Thank you once again, Peter and Kevin - great stuff! *My 160 does need
freq calibration pretty badly, and possibly (probably?) alignment as
well.

Bruce- Hide quoted text -

- Show quoted text -

* * * * * *After changing just 2 or 3 ceramics in the audio stages has
improved enormously in my DX-160. Drift is somewhat moderate, compared
to other radios of similar design and era. But, the band switch is
VERY troublesome. Really kills gain and sometimes creates other
problems as well (requires incessant care,like a newborn). On the
positive note: the IF filter is actually of mechanical type,built
right into the IF coil ! *Calibration is an over statement in this
receiver- it was never designed to be a precision gadjet,alas. *Even
the model which preceded it , the SX/AX- 190 was miles ahead of it in
most respects. * * * * *Radio Shack has been lowering it's standards
ever since...

As I look at the schematic, I realize the band switch actually has
quite a bit to do - each time it is turned, about a half dozen
connections are mechanically made and broken simultaneously. Is this
the source of the trouble? Honestly, I don't think it is a problem in
my radio - but maybe I am missing something.

Bruce