Question about matching transformer (9:1 un-un)
 

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.

Question about matching transformer (9:1 un-un)
 

On Jan 26, 9:32*pm, wrote:
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.

Arthur, thank you, and please accept my apologies for erring on your
name!

Bruce

Question about matching transformer (9:1 un-un)
 

On Jan 27, 12:53*am, bpnjensen wrote:
On Jan 26, 9:32*pm, wrote:





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.

Arthur, thank you, and please accept my apologies for erring on your
name!

Bruce- Hide quoted text -

- Show quoted text -

No problem,Bruce. After the audio modification it's frequency
response will improve substantially . Original design claimed 300Hz-
3 KHz. Ever tried to run it on 12VDC external power supply- may solve
some of the drift. N.B. The IF bandwith is 4 KHz,
if not mistaken. T16 is a coil with a mechanical filter, not very
spectacular at all- has rather broad attenuation skirts for such a
component. May be one day I will swap it with a Murata or NTT ,if they
match the holes. Wonder what impedances are involved here, sometimes
it makes a tremendous difference. No standard Collins (new or old)
filters that I know of will fit in here, thanks God !

Question about matching transformer (9:1 un-un)
 

On Jan 27, 12:53 am, wrote:


Oh, about that GoldPoint bandswitch, Peter. What material is it made of ? If it has silver
contacts,then it is a real switch.


Gold, actually.

Select the number of switch positions you want, stack the layers
you need, and wire it up. Pretty slick. Not cheap, but you'll never
have to screw around with a bandswitch again.

Truthfully, it's overkill for DX-160 and it's family. But then,
anything worth doing is worth overdoing.


http://www.goldpt.com/selector.html