RES: [BITX20] #For Sale A Few QRP Goodies
#for
Puxa, legal encontrar radioamadores que tamb¨¦m falam o ±Ê´Ç°ù³Ù³Ü²µ³Ü¨º²õ! Assim que terminar minhas antenas de apartamento montarei o uBIT 6.1. Grande 73. ? Wow, nice to find radio amateurs who also speak Portuguese! As soon as I finish my apartment antennas I will set up my uBIT 6.1. Large 73. ? Fred Guizini PY2-UBB S?o Paulo - Brazil ? Enviado do para Windows 10 ? ? Tambem falo portugues. Era liinguist em ASA. On Wednesday, November 18, 2020, 3:15:15 PM EST, N8DAH <dherron@...> wrote: Rubens, Simplesmente n?o tenho tempo para brincar com tudo como pensei que faria. Tamb¨¦m estou reduzindo um pouco o barraco e adoro construir coisas. 73
--
David ?N8DAH
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Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
A settable resistor with two terminals is usually called a rheostat.
On Friday, November 20, 2020, 3:45:33 AM EST, Raj vu2zap <rajendrakumargg@...> wrote:
A variable pot is shown with an arrow. A pot that is adjusted once and
set
is called a preset and is shown with a short line instead of
arrow.
?
At 20/11/2020, you wrote:
"what component is P1"
?????
I figured it was a pot but never seen that symbol used before.
---
Darrell Lee
Advanced Data Systems, Inc.
2801 Wade Hampton Blvd.
Suite 115-153
Taylors, SC 29687
864-230-9626 | dlee@...
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Is there a link to the "led/ldr combo" circuit? I get the concept but love shortcuts to their use with a diagram showing components and their values.
Bob ¡ª KK5R
On Friday, November 20, 2020, 3:43:52 AM EST, SIMON ROSS via groups.io <simonr5@...> wrote:
Vk3ye demonstrates the circuit for the led/ldr combo. I¡¯ve built it and it works to cut high audio peaks?
On 19 Nov 2020, at 00:38, iz oos <and2oosiz2@...> wrote:
? Loris, would you think a vogad at the audio output could be a solution to save both sensitivity and hears to some extent? AAT (Automatic Attenuator Control)? _._
Hi Loris,
There are a lot of newbies here and they just don't know. Don't be
angry. Just help them alomng if they are actually open to help. I
started learning about physics and electronics in the early 1950s and I
still don't everything. I am more and moire aware of how much I don't
know. I usually do know where to look:)
73,
Bill KU8H
bark less - wag more
On 11/18/20 7:17 AM, IW4AJR Loris wrote:
> Hi Bill ... I fully agree with you!
> What I am wondering is "why" this forum continues to call AGC a very
> vulgar "ATTENUATOR" even if more or less automatic.
> 73 Loris
>
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Very good information. Very often different words are used where the word is a noun or an adjective when dealing with the same thing. Difference between a Title and a Description.
An amplifier "ceiling effect" would seem logical where the gain is at a set level and it's low enough to control the "loud mouths" on the bands but yet will not impede the lower level signals. No doubt it should be in the IF area and this has been the tradition going back to days of the tube radios. A simple diode was added to the first audio amplifier that formed a power supply that fed back to the IF amplifier/s and controlled their gain. It rectified the carrier at this point and formed a DC signal that corresponded to the station you listened to so the audio output was consistent for most all stations. However, this was simple compared to the hoops you have to jump through when not dealing merely with an AM signal; SSB and other modes are much more challenging to have such a circuit. One designer used what is termed an "audio derived" S-Meter circuit that "might" be adaptable to assist in the AGC feature but still may not be transparent to the user.
A simple RF gain may not serve the purpose since the user may still be constantly using it to control the High vs Low signals heard, for example, in a net. But you'd in effect be using the audio gain and the RF gain together much like the old regenerative control was used along with the tuning control.
Good discussion. Thanks Farhan for this.
Bob ¡ª KK5R
On Friday, November 20, 2020, 2:44:26 AM EST, Ashhar Farhan <farhanbox@...> wrote:
AGC is a feature and attenuation is a function. Automatic Gain control can work using an electronically controlled attenuation in the signal chain or by using variable gain amplifiers somewhere in the chain. the golden rule of good signal processing is to control the gain as early in the signal chain as is possible. The best gain control is to put variable resistor right at the antenna terminal. The reason is very simple: the amplifiers down the chain have to handle weaker signals and weaker signals mean better fidelity. An audio AGC in a conventional superhet where most of the gain is in the IF stage will overload even on a moderate signals due to the distortions in IF amplifiers. Picture this, there is the lowest level signal that the receiver can resolve, this is set by the bandwidth and the noise figure of the receiver. The? highest signal that the receiver can resolve without distorting is determined by the IIP3 and the phase noise of the local oscillator. The range of signals between the minimum discernable signal and the loudest signal that the receiver can handle without noticeable distortion is your dynamic range. Now, consider what happens if you switch on a 10 db attenuator between the antenna and the receiver. the MDS (minimum discernable signal) has to be 10 times more powerful and on the other hand, the signal level at which the distortion starts to show is also up by 10 db. In effect, to borrrow?Rob, NC0B's words, the dynamic range is a moveable window that can be shifted up or down with attenuators. Most receivers are too sensitive for HF bands. For instance, the ubitx is too sensitive for 40 meters, the atmospheric noise is 100 times more powerful than the internal noise (noise floor) of the receiver. This is wasted dynamic range. if we had thrown in a 20 db attenuator, we would hear exactly the same signals as before but our dynamic range would have been 100 times more. Dynamic range doesn't only apply when you are contesting or having a neighbour who transmits 1000 watts, it is a measure of how sweet the receiver sound is as well. So, why is ubitx so needlessly sensitive? That is, because it is meant to work from 10 meters to 80 Meters. That sensitivity will be needed when the 15 meter opens up in a few years from now. RF attenuation does remain the best place to control the gain, even for an AGC system. The challenge is to build a smoothly varying attenuator that doesn't need any active devices. Active devices in wide open receivers like the ubitx can severally compromise the receiver performance.? I am planning to do a video to explain who careful gain distribution is the key to a good radio design. - f
On Fri, Nov 20, 2020 at 9:38 AM TD < dlee@...> wrote: > "what component is P1" ?????
I figured it was a pot but never seen that symbol used before.
---
Darrell Lee
Advanced Data Systems, Inc.
2801 Wade Hampton Blvd.
Suite 115-153
Taylors, SC 29687
864-230-9626 | dlee@...
On 11/19/2020 01:15 PM, IW4AJR Loris wrote:
> Hello TD ...
>
> "what component is P1" ?????
>
> maybe it is simply a resistive trimmer or a potentiometer ???? perhaps
> !!! HAHAHAHA
>
> don't tell me you don't know what P1 is because I don't believe it!
>
> this diagram is just an example of how a simple dynamic compressor
> with a handful of passive components can be made, how to insert it and
> where to insert it in the ?BITX is something you have to decide,
> study it a bit and look at the diagram of the part receiver of the
> ?BITX (from the volume potentiometer to the speaker) and see if you
> need it as an input to the BF amplifier (LM386) or if you want to
> insert it in parallel with the output before the headphone jack.
>
> hi TD ... good job! greetings from IW4AJR Loris
>
>
> Links:
> ------
> [1] /g/BITX20/message/83812
> [2] /mt/78337317/4392615
> [3] /g/BITX20/post
> [4] /g/BITX20/mutehashtag/ubitx
> [5] /g/BITX20/mutehashtag/ubitxv6
> [6] /g/BITX20/editsub/4392615
> [7] /g/BITX20/leave/defanged
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
I used a simple circuit using a ldr and an led to attenuate the loud audio and also connected a meter. It works well. Vk3ye shows it on YouTube?
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Show quoted text
On 19 Nov 2020, at 08:55, Bob Lunsford via groups.io <nocrud222@...> wrote:
?
I tried the scheme with two computer switching diodes from the earphone lines to ground and it does work although not as effectively as I'd hoped. I'll prepare a headset to do this for me and I expect it to still work as designed with other applications. May have to change the connector, though, to avoid cutting the headphone line.
Bob ¡ª KK5R
On Thursday, November 19, 2020, 2:12:45 AM EST, Bill Cromwell <wrcromwell@...> wrote:
Hi, I have done and will be doing it again. When very loud signals suddenly appear in the cans, instead of making your ears bleed you will hear it suddenly very distorted and maybe a little louder. That is your cue to turn down the volume. It won't function like the AGC you are used to. It will protect your hearing. 73, Bill? KU8H bark less - wag more On 11/18/20 7:56 PM, Bob Lunsford via groups.io wrote: > For headphones, I wonder if two diodes with polarities reversed from > each other across the headphone line would provide some hearing > protection...? Or a pair of reversed polarity in series if the volume > were affected too much. Does this cause severe distortion? (I've read > about doing this but never tried it.) > > By the way, what is "vogad"??? > > Bob ¡ª KK5R > > On Wednesday, November 18, 2020, 7:38:16 PM EST, iz oos > < and2oosiz2@...> wrote: > > > Loris, would you think a vogad at the audio output could be a solution > to save both sensitivity and hears to some extent? > > Il mer 18 nov 2020 06:10 PM Arv Evans < arvid.evans@... > <mailto: arvid.evans@...>> ha scritto: > >? ? AAT (Automatic Attenuator Control)? >? ? _._ > > >? ? On Wed, Nov 18, 2020 at 5:32 AM Bill Cromwell < wrcromwell@...>? ? <mailto: wrcromwell@...>> wrote: > >? ? ? ? Hi Loris, > >? ? ? ? There are a lot of newbies here and they just don't know. Don't be >? ? ? ? angry. Just help them alomng if they are actually open to help. I >? ? ? ? started learning about physics and electronics in the early >? ? ? ? 1950s and I >? ? ? ? still don't everything. I am more and moire aware of how much I >? ? ? ? don't >? ? ? ? know. I usually do know where to look:) > >? ? ? ? 73, > >? ? ? ? Bill KU8H > >? ? ? ? bark less - wag more > >? ? ? ? On 11/18/20 7:17 AM, IW4AJR Loris wrote: >? ? ? ? ? > Hi Bill ... I fully agree with you! >? ? ? ? ? > What I am wondering is "why" this forum continues to call AGC >? ? ? ? a very >? ? ? ? ? > vulgar "ATTENUATOR" even if more or less automatic. >? ? ? ? ? > 73 Loris >? ? ? ? ? > > > > > > >
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Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Nice discussion all around. The gain in the ubitx is nicely arranged.
Usually the RF attenuator function in the most sophisticated HF receivers is a maual conrol. Since the ubitx does not use a presmp, I don't require an RF attenuation control.
A radio operator csn adjust also the audio gain. But a little AGC can help here.
The LED/LDR circuit appears to act slightly logarithmic which is useful. It works pleasantly with the ubitx gain distribution.?
A lossy attenuator network at the front of the ubitx would be a bad thing at high part of HF. An experimentor should evaluate sensitivity on 28 Mhz with and without it. Meanehile, leave it out if you don't need it.?
73 curt
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Re: Alternative Calibration Procedure uBITx v6
This is a simple & free method because almost all digital receiving software (FLDGI, etc) accurately measure the audio freq beat tone far in excess of your needs. ?
toggle quoted message
Show quoted text
On Nov 19, 2020, at 17:35, iz oos <and2oosiz2@...> wrote:
? Repeat the same on other time signals such as 10 15mhz and beyond when propagation is in a good mood Following the calibration procedure for my v6, I had trouble zero beating a carrier, so I tried a modified approach that seems to work better for me. With the radio in LSB mode, I tuned 1 kHz above WWV at 5 MHz. WWV's carrier thus creates a 1 kHz tone. I used a program with an audio waterfall (I used FLDIGI) and adjusted the uBITx's tuning calibration until the tone was at 1 kHz.
73,
Mark
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Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Thank you, Raj, for useful information as always.
One point that has not been brought out for the LID/LIR combination is that most LIR (if not all) are logarithmic in response.? That would more closely match an audio taper pot that would require a complex circuit to get the same log response.? If this is in error please let me know.
73
Evan
AC9TU
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
A variable pot is shown with an arrow. A pot that is adjusted once and
set
is called a preset and is shown with a short line instead of
arrow.
?
At 20/11/2020, you wrote:
"what component is P1"
?????
I figured it was a pot but never seen that symbol used before.
---
Darrell Lee
Advanced Data Systems, Inc.
2801 Wade Hampton Blvd.
Suite 115-153
Taylors, SC 29687
864-230-9626 | dlee@...
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Vk3ye demonstrates the circuit for the led/ldr combo. I¡¯ve built it and it works to cut high audio peaks?
toggle quoted message
Show quoted text
On 19 Nov 2020, at 00:38, iz oos <and2oosiz2@...> wrote:
? Loris, would you think a vogad at the audio output could be a solution to save both sensitivity and hears to some extent? AAT (Automatic Attenuator Control)? _._
Hi Loris,
There are a lot of newbies here and they just don't know. Don't be
angry. Just help them alomng if they are actually open to help. I
started learning about physics and electronics in the early 1950s and I
still don't everything. I am more and moire aware of how much I don't
know. I usually do know where to look:)
73,
Bill KU8H
bark less - wag more
On 11/18/20 7:17 AM, IW4AJR Loris wrote:
> Hi Bill ... I fully agree with you!
> What I am wondering is "why" this forum continues to call AGC a very
> vulgar "ATTENUATOR" even if more or less automatic.
> 73 Loris
>
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
AGC is a feature and attenuation is a function. Automatic Gain control can work using an electronically controlled attenuation in the signal chain or by using variable gain amplifiers somewhere in the chain. the golden rule of good signal processing is to control the gain as early in the signal chain as is possible. The best gain control is to put variable resistor right at the antenna terminal. The reason is very simple: the amplifiers down the chain have to handle weaker signals and weaker signals mean better fidelity. An audio AGC in a conventional superhet where most of the gain is in the IF stage will overload even on a moderate signals due to the distortions in IF amplifiers. Picture this, there is the lowest level signal that the receiver can resolve, this is set by the bandwidth and the noise figure of the receiver. The? highest signal that the receiver can resolve without distorting is determined by the IIP3 and the phase noise of the local oscillator. The range of signals between the minimum discernable signal and the loudest signal that the receiver can handle without noticeable distortion is your dynamic range. Now, consider what happens if you switch on a 10 db attenuator between the antenna and the receiver. the MDS (minimum discernable signal) has to be 10 times more powerful and on the other hand, the signal level at which the distortion starts to show is also up by 10 db. In effect, to borrrow?Rob, NC0B's words, the dynamic range is a moveable window that can be shifted up or down with attenuators. Most receivers are too sensitive for HF bands. For instance, the ubitx is too sensitive for 40 meters, the atmospheric noise is 100 times more powerful than the internal noise (noise floor) of the receiver. This is wasted dynamic range. if we had thrown in a 20 db attenuator, we would hear exactly the same signals as before but our dynamic range would have been 100 times more. Dynamic range doesn't only apply when you are contesting or having a neighbour who transmits 1000 watts, it is a measure of how sweet the receiver sound is as well. So, why is ubitx so needlessly sensitive? That is, because it is meant to work from 10 meters to 80 Meters. That sensitivity will be needed when the 15 meter opens up in a few years from now. RF attenuation does remain the best place to control the gain, even for an AGC system. The challenge is to build a smoothly varying attenuator that doesn't need any active devices. Active devices in wide open receivers like the ubitx can severally compromise the receiver performance.? I am planning to do a video to explain who careful gain distribution is the key to a good radio design. - f
On Fri, Nov 20, 2020 at 9:38 AM TD < dlee@...> wrote: > "what component is P1" ?????
I figured it was a pot but never seen that symbol used before.
---
Darrell Lee
Advanced Data Systems, Inc.
2801 Wade Hampton Blvd.
Suite 115-153
Taylors, SC 29687
864-230-9626 | dlee@...
On 11/19/2020 01:15 PM, IW4AJR Loris wrote:
> Hello TD ...
>
> "what component is P1" ?????
>
> maybe it is simply a resistive trimmer or a potentiometer ???? perhaps
> !!! HAHAHAHA
>
> don't tell me you don't know what P1 is because I don't believe it!
>
> this diagram is just an example of how a simple dynamic compressor
> with a handful of passive components can be made, how to insert it and
> where to insert it in the ?BITX is something you have to decide,
> study it a bit and look at the diagram of the part receiver of the
> ?BITX (from the volume potentiometer to the speaker) and see if you
> need it as an input to the BF amplifier (LM386) or if you want to
> insert it in parallel with the output before the headphone jack.
>
> hi TD ... good job! greetings from IW4AJR Loris
>
>
> Links:
> ------
> [1] /g/BITX20/message/83812
> [2] /mt/78337317/4392615
> [3] /g/BITX20/post
> [4] /g/BITX20/mutehashtag/ubitx
> [5] /g/BITX20/mutehashtag/ubitxv6
> [6] /g/BITX20/editsub/4392615
> [7] /g/BITX20/leave/defanged
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
"what component is P1" ????? I figured it was a pot but never seen that symbol used before. --- Darrell Lee Advanced Data Systems, Inc. 2801 Wade Hampton Blvd. Suite 115-153 Taylors, SC 29687 864-230-9626 | dlee@... On 11/19/2020 01:15 PM, IW4AJR Loris wrote: Hello TD ...
"what component is P1" ?????
maybe it is simply a resistive trimmer or a potentiometer ???? perhaps
!!! HAHAHAHA
don't tell me you don't know what P1 is because I don't believe it!
this diagram is just an example of how a simple dynamic compressor
with a handful of passive components can be made, how to insert it and
where to insert it in the ?BITX is something you have to decide,
study it a bit and look at the diagram of the part receiver of the
?BITX (from the volume potentiometer to the speaker) and see if you
need it as an input to the BF amplifier (LM386) or if you want to
insert it in parallel with the output before the headphone jack.
hi TD ... good job! greetings from IW4AJR Loris
Links:
------
[1] /g/BITX20/message/83812
[2] /mt/78337317/4392615
[3] /g/BITX20/post
[4] /g/BITX20/mutehashtag/ubitx
[5] /g/BITX20/mutehashtag/ubitxv6
[6] /g/BITX20/editsub/4392615
[7] /g/BITX20/leave/defanged
|
Re: Alternative Calibration Procedure uBITx v6
Repeat the same on other time signals such as 10 15mhz and beyond when propagation is in a good mood
Following the calibration procedure for my v6, I had trouble zero beating a carrier, so I tried a modified approach that seems to work better for me. With the radio in LSB mode, I tuned 1 kHz above WWV at 5 MHz. WWV's carrier thus creates a 1 kHz tone. I used a program with an audio waterfall (I used FLDIGI) and adjusted the uBITx's tuning calibration until the tone was at 1 kHz.
73,
Mark
|
Re: Alternative Calibration Procedure uBITx v6
Hi Mark
Finally someone using a "lab" approach to calibrate a receiver!
Great approach!
For the wealthiest:
1) fix a frequency on the receiver in LSB,
2) fix the frequency of the RF generator 1kHz above the chosen frequency,
3) connect a frequency meter to the audio output,
4) act on the calibration until reading exactly 1kHz !
Easier than that ...!
Great job Mark ! thanks !
greetings Loris IW4AJR
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Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Hello TD ... "what component is P1" ?????
maybe it is simply a resistive trimmer or a potentiometer ???? perhaps !!! HAHAHAHA
?
don't tell me you don't know what P1 is because I don't believe it!
?
this diagram is just an example of how a simple dynamic compressor with a handful of passive components can be made, how to insert it and where to insert it in the ?BITX is something you have to decide, study it a bit and look at the diagram of the part receiver of the ?BITX (from the volume potentiometer to the speaker) and see if you need it as an input to the BF amplifier (LM386) or if you want to insert it in parallel with the output before the headphone jack.
?
hi TD ... good job! greetings from IW4AJR Loris
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
What component is P1? Where in a transceiver would one connect this circuit?
Thanks,
---
Darrell Lee
Advanced Data Systems, Inc.
2801 Wade Hampton Blvd.
Suite 115-153
Taylors, SC 29687
864-230-9626 | dlee@...
toggle quoted message
Show quoted text
On 11/19/2020 10:27 AM, IW4AJR Loris wrote: Hi Bob,
If you want to try out an "ancient" headphone dynamics compressor,
known to QST readers in the 60s, you can try the attached diagram.
The attached simulation is done with LTspice, the values are a little
different because I have simulated different solutions, but the
substance does not change ... "IT WORKS" !!! ...
P.S. the simulation is done by combining 3 frequencies (300Hz, 1.650Hz
and 3.000Hz) to see the behavior in the normal OM reception range and
check for any harmonic distortions introduced, the result is
excellent, from the FFT the only harmonics present are over 5kHz , in
an area where they should not give distortions.
Good experiments and a dear greeting from IW4AJR Loris
Links:
------
[1] /g/BITX20/message/83809
[2] /mt/78337317/4392615
[3] /g/BITX20/post
[4] /g/BITX20/mutehashtag/ubitx
[5] /g/BITX20/mutehashtag/ubitxv6
[6] /g/BITX20/editsub/4392615
[7] /g/BITX20/leave/defanged
|
I also forgot to mention the project from Scullcom.uk for a 10Mhz reference oscillator. Granted it is designed to be more of a bench reference, but I'm sure you could accommodate for that! His project is based on the Neo 7m for reasons he describes in the video. I've not seen many of those around so if you wanted to do this project you may want to look for the Neo 8M/N or other newer variants that have the 10Mhz capability.
?
http://www.scullcom.uk/category/projects/frequency-reference/
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Hi Bob,
?
If you want to try out an "ancient" headphone dynamics compressor, known to QST readers in the 60s, you can try the attached diagram.
?
The attached simulation is done with LTspice, the values are a little different because I have simulated different solutions, but the substance does not change ... "IT WORKS" !!! ...
P.S. the simulation is done by combining 3 frequencies (300Hz, 1.650Hz and 3.000Hz) to see the behavior in the normal OM reception range and check for any harmonic distortions introduced, the result is excellent, from the FFT the only harmonics present are over 5kHz , in an area where they should not give distortions.
?
|
Dear Ashhar,
Thanks a lot for the detailed solution. The two ubitx are arriving soon
home, I'll try to replicate here, I have a GPSDO with a 10MHz output.
Rafael
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On 11/19/20 12:48 AM, Ashhar Farhan wrote: I tried something a year ago or so. I was attempting to reduce the
phase noise on Si5351 using an external oscillator instead of the
internal oscillator.
So, this is how it worked.?
1. You take a 10 MHz TCXO, (subsitute this with a GPS source for a
GPSDO) and divide it by 2 in a 74HC74. The output is rich in harmonics
at 5 MHz.
2. You feed the 5 MHz square wave into a triple tuned bandpass filter
at 25 mhz to isolate the 5th harmonic. This will be weak, add an
amplifier of 16 db to bring it up.
3. Feed this to the xin input of the Si5351.
Now, your Si5351 is GPS disciplined.
On Thu 19 Nov, 2020, 7:35 AM Rafael Diniz, <rafael@...
<mailto:rafael@...>> wrote:
Very interesting Jason! Tks!
Rafael
On 11/17/20 10:47 AM, Jason Pirok wrote:
> I just bought one of the VFO/SigGen kits from QRP-Labs and they
> already have a GPS disciplined option for it if you want to try it
> out. It is only 1PPS but apparently does the job. I haven't built my
> GPS kit yet so I can't give any personal details atm. You have to
> provide the 5v supply on your own so that is some extra work.
>
> Just a thought in case you hadn't seen that project yet.
>
|
Re: Question: Why do you call "AGC" a simple automatic antenna "attenuator" in this forum?
#ubitx
#ubitxv6
Hi Bob,
?
why go crazy to try and try to invent hot water?
?
In HiFi amplifiers, the problem of ear protection in headphones has already been solved for almost a hundred years! just make a resistive divider on the output with two resistances between the signal (positive pole of the speaker) and ground (120¦¸ / 1W + 56¦¸ / 1 / 2W) and that's it, have you ever skipped eardrums listening to a vinyl ad high dynamics with headphones? if you love listening to Classical Music, sudden changes from a pianissimo to a fortissimo are the order of the day!
Look at the attached diagram, it is taken from a SUPERSCOPE A-260 from the 70s ... there are so many things to experience on the ?BITX without getting lost in things that have already been solved for decades!
Good experiments and a dear greeting from IW4AJR Loris 
|
Bob Lunsford
Raj vu2zap