Topics

Gain control


Charles W. Powell
 

I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O


Dave Benson
 

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it.

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O



Charles W. Powell
 

Thanks Dave.

I actually noticed the counterclockwise effect on the gain.  It seems like the sensitivity is reduced a bit because I am hearing very little noise at all, but I still hear readable signals.  It’s a remarkable phenomenon.  If placing another resistor in parallel won’t hurt U1, I may tack one in on the bottom of the board to see if it slows the rate of change ever so slightly.  It shouldn’t make any difference at the fully clockwise setting.

Excellent news about Mode A/B  for keying, although I have had a lot of fun having it necessary to use the straight key!  Keeps my fist in shape.

The QSOs have taken patience, but the fact is that they are still there to be found.  I am amazed that some of the weaker stations can even hear me.  Of course, it also helps to be in a setting where the noise floor is minimal.

72,

Charles - NK8O



On May 10, 2018, at 5:25 AM, Dave Benson <davek1swl@...> wrote:

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it.

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O





Dave Benson
 

Charles-

(Educated guess) The gain increase at full counterclockwise is likely due to stray capacitance between two of the pot terminals.

Of more importance, I just wrapped up testing on the revised Hilltopper-20 firmware. I've burned several extra copies of the controller IC.  My wife's away for the afternoon (my truck's in the shop), so one will be in the mail to you tomorrow.   I'll include descriptions of the changed functionality.

Thanks for your patience!

73- Dave, K1SWL

On Thu, May 10, 2018 at 7:29 AM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
Thanks Dave.

I actually noticed the counterclockwise effect on the gain.  It seems like the sensitivity is reduced a bit because I am hearing very little noise at all, but I still hear readable signals.  It’s a remarkable phenomenon.  If placing another resistor in parallel won’t hurt U1, I may tack one in on the bottom of the board to see if it slows the rate of change ever so slightly.  It shouldn’t make any difference at the fully clockwise setting.

Excellent news about Mode A/B  for keying, although I have had a lot of fun having it necessary to use the straight key!  Keeps my fist in shape.

The QSOs have taken patience, but the fact is that they are still there to be found.  I am amazed that some of the weaker stations can even hear me.  Of course, it also helps to be in a setting where the noise floor is minimal.

72,

Charles - NK8O



On May 10, 2018, at 5:25 AM, Dave Benson <davek1swl@...> wrote:

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it.

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O






Charles W. Powell
 

Oh don’t worry at all.  Thanks for sending that along.  I won’t be home for a while in any case.  Hamvention this weekend (all set up in the tent before the rain started!) and then up to Minnesota to help my wife with babysitting our granddaughter.  But I am going to make a special go-bag for the hilltopper and a wire 1/4 wave vertical for it.  I plan to do some serious goofing off and playing radio on my next “work” trip.  That will give me a good opportunity to really try it out.  

Don’t feel obligated to hurry anything along for me.  I’m really delighted with this little radio.  In some ways it’s more fun than my KX2!

I may test your theory about stray capacitance and the gain control.  If it is, a finger moving in and out should change the coupling so I will try this with the lid off some time.

I think between the last two kits I built (this one and an Elecraft T1 tuner) I have really refined my soldering technique.  If you make a Hilltopper 40 or 30 I may have to build one (or both!)

72,

Charles - NK8O

On May 17, 2018, at 4:56 PM, Dave Benson <davek1swl@...> wrote:

Charles-

(Educated guess) The gain increase at full counterclockwise is likely due to stray capacitance between two of the pot terminals.

Of more importance, I just wrapped up testing on the revised Hilltopper-20 firmware. I've burned several extra copies of the controller IC.  My wife's away for the afternoon (my truck's in the shop), so one will be in the mail to you tomorrow.   I'll include descriptions of the changed functionality.

Thanks for your patience!

73- Dave, K1SWL

On Thu, May 10, 2018 at 7:29 AM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
Thanks Dave.

I actually noticed the counterclockwise effect on the gain.  It seems like the sensitivity is reduced a bit because I am hearing very little noise at all, but I still hear readable signals.  It’s a remarkable phenomenon.  If placing another resistor in parallel won’t hurt U1, I may tack one in on the bottom of the board to see if it slows the rate of change ever so slightly.  It shouldn’t make any difference at the fully clockwise setting.

Excellent news about Mode A/B  for keying, although I have had a lot of fun having it necessary to use the straight key!  Keeps my fist in shape.

The QSOs have taken patience, but the fact is that they are still there to be found.  I am amazed that some of the weaker stations can even hear me.  Of course, it also helps to be in a setting where the noise floor is minimal.

72,

Charles - NK8O



On May 10, 2018, at 5:25 AM, Dave Benson <davek1swl@...> wrote:

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it. 

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O









Dave Benson
 

Charles-

Have fun at the hamvention!   .... and with the granddaughter.  My wife's in Massachusetts- our granddaughter tested positive for strep- home today-  and daughter needed to work.

Glad you're enjoying the rig! I'll be able to supply a conversion kit for 40M shortly. The top cover is still an issue,though, being labeled for 20M

73- Dave, K1SWL.

On Thu, May 17, 2018 at 5:41 PM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
Oh don’t worry at all.  Thanks for sending that along.  I won’t be home for a while in any case.  Hamvention this weekend (all set up in the tent before the rain started!) and then up to Minnesota to help my wife with babysitting our granddaughter.  But I am going to make a special go-bag for the hilltopper and a wire 1/4 wave vertical for it.  I plan to do some serious goofing off and playing radio on my next “work” trip.  That will give me a good opportunity to really try it out.  

Don’t feel obligated to hurry anything along for me.  I’m really delighted with this little radio.  In some ways it’s more fun than my KX2!

I may test your theory about stray capacitance and the gain control.  If it is, a finger moving in and out should change the coupling so I will try this with the lid off some time.

I think between the last two kits I built (this one and an Elecraft T1 tuner) I have really refined my soldering technique.  If you make a Hilltopper 40 or 30 I may have to build one (or both!)

72,

Charles - NK8O


On May 17, 2018, at 4:56 PM, Dave Benson <davek1swl@...> wrote:

Charles-

(Educated guess) The gain increase at full counterclockwise is likely due to stray capacitance between two of the pot terminals.

Of more importance, I just wrapped up testing on the revised Hilltopper-20 firmware. I've burned several extra copies of the controller IC.  My wife's away for the afternoon (my truck's in the shop), so one will be in the mail to you tomorrow.   I'll include descriptions of the changed functionality.

Thanks for your patience!

73- Dave, K1SWL

On Thu, May 10, 2018 at 7:29 AM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
Thanks Dave.

I actually noticed the counterclockwise effect on the gain.  It seems like the sensitivity is reduced a bit because I am hearing very little noise at all, but I still hear readable signals.  It’s a remarkable phenomenon.  If placing another resistor in parallel won’t hurt U1, I may tack one in on the bottom of the board to see if it slows the rate of change ever so slightly.  It shouldn’t make any difference at the fully clockwise setting.

Excellent news about Mode A/B  for keying, although I have had a lot of fun having it necessary to use the straight key!  Keeps my fist in shape.

The QSOs have taken patience, but the fact is that they are still there to be found.  I am amazed that some of the weaker stations can even hear me.  Of course, it also helps to be in a setting where the noise floor is minimal.

72,

Charles - NK8O



On May 10, 2018, at 5:25 AM, Dave Benson <davek1swl@...> wrote:

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it. 

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O










Charles W. Powell
 

I returned home today to find a package from Dave Benson, containing an ATmega chip.  I am happy to report that Curtis modes A & B seem to work quite well, and they are very easy to swap.  I didn’t reverse the paddles but I know that works.  After a quick re-alignment, I did a quick check of receiver sensitivity.  I could still hear a signal at -130 dBm, although I must admit that I probably couldn’t copy anything there.  The good news is that even under the quietest conditions, the noise floor is about -120 dBm.

On Wednesday I fly to Alabama, and the Hilltopper will go as my HF entertainment.  I’ll be tuning a wire 1/4 wave vertical tomorrow, trying to center it at 14.030.  I found a BNC binding post that will be perfect for the job 

Look for me on the air in the afternoons from the 31st through the 6th of June, EM71gf (Dothan AL).

72,

Charles - NK8O  

On May 17, 2018, at 5:11 PM, Dave Benson <davek1swl@...> wrote:

Charles-

Have fun at the hamvention!   .... and with the granddaughter.  My wife's in Massachusetts- our granddaughter tested positive for strep- home today-  and daughter needed to work.

Glad you're enjoying the rig! I'll be able to supply a conversion kit for 40M shortly. The top cover is still an issue,though, being labeled for 20M

73- Dave, K1SWL.

On Thu, May 17, 2018 at 5:41 PM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
Oh don’t worry at all.  Thanks for sending that along.  I won’t be home for a while in any case.  Hamvention this weekend (all set up in the tent before the rain started!) and then up to Minnesota to help my wife with babysitting our granddaughter.  But I am going to make a special go-bag for the hilltopper and a wire 1/4 wave vertical for it.  I plan to do some serious goofing off and playing radio on my next “work” trip.  That will give me a good opportunity to really try it out.  

Don’t feel obligated to hurry anything along for me.  I’m really delighted with this little radio.  In some ways it’s more fun than my KX2!

I may test your theory about stray capacitance and the gain control.  If it is, a finger moving in and out should change the coupling so I will try this with the lid off some time.

I think between the last two kits I built (this one and an Elecraft T1 tuner) I have really refined my soldering technique.  If you make a Hilltopper 40 or 30 I may have to build one (or both!)

72,

Charles - NK8O


On May 17, 2018, at 4:56 PM, Dave Benson <davek1swl@...> wrote:

Charles-

(Educated guess) The gain increase at full counterclockwise is likely due to stray capacitance between two of the pot terminals.

Of more importance, I just wrapped up testing on the revised Hilltopper-20 firmware. I've burned several extra copies of the controller IC.  My wife's away for the afternoon (my truck's in the shop), so one will be in the mail to you tomorrow.   I'll include descriptions of the changed functionality.

Thanks for your patience!

73- Dave, K1SWL

On Thu, May 10, 2018 at 7:29 AM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
Thanks Dave.

I actually noticed the counterclockwise effect on the gain.  It seems like the sensitivity is reduced a bit because I am hearing very little noise at all, but I still hear readable signals.  It’s a remarkable phenomenon.  If placing another resistor in parallel won’t hurt U1, I may tack one in on the bottom of the board to see if it slows the rate of change ever so slightly.  It shouldn’t make any difference at the fully clockwise setting.

Excellent news about Mode A/B  for keying, although I have had a lot of fun having it necessary to use the straight key!  Keeps my fist in shape.

The QSOs have taken patience, but the fact is that they are still there to be found.  I am amazed that some of the weaker stations can even hear me.  Of course, it also helps to be in a setting where the noise floor is minimal.

72,

Charles - NK8O



On May 10, 2018, at 5:25 AM, Dave Benson <davek1swl@...> wrote:

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it. 

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O













Dave Benson
 

Charles-

Thanks for the feedback!  Have fun on your next trip.

73- Dave, K1SWL

On Tue, May 29, 2018 at 1:02 AM, Charles W. Powell via Groups.Io <doctorcwp@...> wrote:
I returned home today to find a package from Dave Benson, containing an ATmega chip.  I am happy to report that Curtis modes A & B seem to work quite well, and they are very easy to swap.  I didn’t reverse the paddles but I know that works.  After a quick re-alignment, I did a quick check of receiver sensitivity.  I could still hear a signal at -130 dBm, although I must admit that I probably couldn’t copy anything there.  The good news is that even under the quietest conditions, the noise floor is about -120 dBm.

On Wednesday I fly to Alabama, and the Hilltopper will go as my HF entertainment.  I’ll be tuning a wire 1/4 wave vertical tomorrow, trying to center it at 14.030.  I found a BNC binding post that will be perfect for the job 

Look for me on the air in the afternoons from the 31st through the 6th of June, EM71gf (Dothan AL).

72,

Charles - NK8O  

On May 17, 2018, at 5:11 PM, Dave Benson <davek1swl@...> wrote:

Charles-

Have fun at the hamvention!   .... and with the granddaughter.  My wife's in Massachusetts- our granddaughter tested positive for strep- home today-  and daughter needed to work.

Glad you're enjoying the rig! I'll be able to supply a conversion kit for 40M shortly. The top cover is still an issue,though, being labeled for 20M

73- Dave, K1SWL.

On Thu, May 17, 2018 at 5:41 PM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
Oh don’t worry at all.  Thanks for sending that along.  I won’t be home for a while in any case.  Hamvention this weekend (all set up in the tent before the rain started!) and then up to Minnesota to help my wife with babysitting our granddaughter.  But I am going to make a special go-bag for the hilltopper and a wire 1/4 wave vertical for it.  I plan to do some serious goofing off and playing radio on my next “work” trip.  That will give me a good opportunity to really try it out.  

Don’t feel obligated to hurry anything along for me.  I’m really delighted with this little radio.  In some ways it’s more fun than my KX2!

I may test your theory about stray capacitance and the gain control.  If it is, a finger moving in and out should change the coupling so I will try this with the lid off some time.

I think between the last two kits I built (this one and an Elecraft T1 tuner) I have really refined my soldering technique.  If you make a Hilltopper 40 or 30 I may have to build one (or both!)

72,

Charles - NK8O


On May 17, 2018, at 4:56 PM, Dave Benson <davek1swl@...> wrote:

Charles-

(Educated guess) The gain increase at full counterclockwise is likely due to stray capacitance between two of the pot terminals.

Of more importance, I just wrapped up testing on the revised Hilltopper-20 firmware. I've burned several extra copies of the controller IC.  My wife's away for the afternoon (my truck's in the shop), so one will be in the mail to you tomorrow.   I'll include descriptions of the changed functionality.

Thanks for your patience!

73- Dave, K1SWL

On Thu, May 10, 2018 at 7:29 AM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
Thanks Dave.

I actually noticed the counterclockwise effect on the gain.  It seems like the sensitivity is reduced a bit because I am hearing very little noise at all, but I still hear readable signals.  It’s a remarkable phenomenon.  If placing another resistor in parallel won’t hurt U1, I may tack one in on the bottom of the board to see if it slows the rate of change ever so slightly.  It shouldn’t make any difference at the fully clockwise setting.

Excellent news about Mode A/B  for keying, although I have had a lot of fun having it necessary to use the straight key!  Keeps my fist in shape.

The QSOs have taken patience, but the fact is that they are still there to be found.  I am amazed that some of the weaker stations can even hear me.  Of course, it also helps to be in a setting where the noise floor is minimal.

72,

Charles - NK8O



On May 10, 2018, at 5:25 AM, Dave Benson <davek1swl@...> wrote:

Charles-

The gain control arrangement is a direct copy borrowed from my older SW+ series. It has fairly limited adjustment range (about 30 dB). Of most interest to me, the gain picks back up at the full counterclockwise position. I suspect it's probably a stray capacitance effect, but I haven't had a chance to investigate it. 

Mode A / Mode B selection :  now working.   EEPROM storage/retrieval of that selection needs work and then it's good.

//BTW-  Excellent job on your picnic-table portable adventures. You're doing well despite terrible band conditions!

Dave-   K1SWL

On Wed, May 9, 2018 at 10:47 PM, Charles W. Powell via Groups.Io <doctorcwp=yahoo.com@groups.io> wrote:
I notice that the gain on the Hilltopper is mostly useful in the top 25% of the control.  Is there a way to balance this out a little?  What would happen if a parallel resistor were placed across the fixed pot points, say, 5000 ohms added to make the overall resistance 2500 ohms, or 10K to make a total of 3333 ohms, and a bit less of a change with moving the wiper of the pot?  I'm not an EE so I don't know if this would screw up the input to U1.  Am I on the wrong track?

72,

Charles - NK8O