Topics

Mic upgrade


Chuck Eglhaut
 

Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


Gordon Gibby
 

You can use a microphone with a preamp, or you can easily make a one transistor preamp, but be careful that you aren’t  really overloading systems & creating more distortion in an effort to have more power!   A simple 2N3904 transistor and a few resistors and you can have a preamp with a voltage gain of five or 10 which will do a lot for you.  Plus, learning a little bit about common emitter transistor biasing and gain control will do a lot towards helping you towards higher licensure


On Aug 12, 2020, at 08:42, Chuck Eglhaut <ceglhaut@...> wrote:

Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


Chuck Eglhaut
 

Ok Gordon
Appreciate the input. I been away from Ham Radio for 35 yrs. I starting back at it and starting with new equipment I have one radio A Icom 22s 2 meter mobile.
so I am starting all over with the shack. I’ll be 73 in a couple weeks I am retired. M aybe I can get it all together.
thanks for input 

73
KA3DFK


 


Evan Hand
 

Chuck,
To answer your question, yes I have used a "CB" power mic with the uBITX, both v4 and v5 (In that area they are really the same).  It does help with the power out, however as Gordon points out, you really need to verify that you are not overdriving the audio and causing "splatter."

The best way to verify is with a two-tone audio .wav file played through speakers and then through the mic.  You would verify on an oscilloscope that the output is still linear.  Another way is to use another receiver to verify audio quality, one with a band scope like an SDR with a waterfall display is better than one without (with this one you need to verify that you are not overloading the SDR input vs reading a splatter).   If you do not have any of the above, the other choice without another ham to help is to adjust the power out to be about the same as CW with a constant tone or whistle that would be at the same level as your speech.

The above are just suggestions.  You are responsible for the purity of your signal.  The best way in my opinion would be to measure the signal with a spectrum analyzer and have another ham verify on their receiver.  At less than 15 watts, I doubt that there is much risk of a notice of violation, just comments from other hams on your signal quality.  If you feed it to a power amp, then you would be at higher risk.
73
Evan
AC9TU

PS: I have noted that when you overdrive the audio, the RF feedback increases significantly, causing other problems. 


Greg Steele
 

I did!  I bought a PowerMic from Amazon, and some 4pin microphone sockets.  I wired the Mic +/- connections to a lead off the 'Audio' header on my V6.1 and to ground.  The PTT I had to solder a wire to the underside of the board where the Mic/PTT jack is for the PTT line, and string it to the 4pin mic connector I mounted on the side of the uBitx.  Do not push the mic pre-amp up to 11! I would get splatter and rf back into the rig where it would do strange things to the display.  The stock mic is a weenie, the power mic made a world of difference with my SSB contacts. Went from a 5x3 to 5x7 (depending on conditions).  
GL and 73
KA3WBO

On Wed, Aug 12, 2020 at 8:42 AM Chuck Eglhaut <ceglhaut@...> wrote:
Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


Alex
 

Hi Chuck, I can identify with your situation very much, I've been away from the hobby for 20 years my self and the last use was maritime mobile for 4 years ending in 2001.  I'm 73 YO now and have just bought a v6 transceiver and have enjoyed read this group's threads for the last couple of months. 

looking forward to reading about your journey  in getting back into the hobby.

73,
Alex WD2T

On Wed, Aug 12, 2020 at 9:07 AM Chuck Eglhaut <ceglhaut@...> wrote:

Ok Gordon
Appreciate the input. I been away from Ham Radio for 35 yrs. I starting back at it and starting with new equipment I have one radio A Icom 22s 2 meter mobile.
so I am starting all over with the shack. I’ll be 73 in a couple weeks I am retired. M aybe I can get it all together.
thanks for input 

73
KA3DFK


 


Arv Evans
 

Most ham radio systems seem designed for close-talking the microphone.
Some non-ham systems are designed for full-room pickup of audio.  This is 
probably not good for ham radio because it brings in a lot of room echo or 
road-noise if mobile.  

Yes, many in this group have experimented with powered microphones.   The 
result can be good or bad.  You need to know how the modulation circuitry 
works and you need to have some way to monitor the output waveform to 
insure that you are not over-driving the audio input and modulation circuits.
Over-driving the sideband modulation circuit can result in many harmonics 
of the audio frequency, and harmonics of the RF frequency being present in 
your transmit signal.  

Arv
_._



On Wed, Aug 12, 2020 at 6:42 AM Chuck Eglhaut <ceglhaut@...> wrote:
Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


Bob Lunsford
 

Here's something I got from Forrest Mims' Engineers' Notebook...

Bob — KK5R

Inline image


On Wednesday, August 12, 2020, 8:50:42 AM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


You can use a microphone with a preamp, or you can easily make a one transistor preamp, but be careful that you aren’t  really overloading systems & creating more distortion in an effort to have more power!   A simple 2N3904 transistor and a few resistors and you can have a preamp with a voltage gain of five or 10 which will do a lot for you.  Plus, learning a little bit about common emitter transistor biasing and gain control will do a lot towards helping you towards higher licensure


On Aug 12, 2020, at 08:42, Chuck Eglhaut <ceglhaut@...> wrote:

Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


Bob Lunsford
 

An old tradition in hamdom where an experimental microphone is tested running a mic preamp circuit is to monitor the output with a voltmeter across the dummy load and start cranking up the gain on the preamp while talking into the mic. When the output peaks out (using a monitor detector as with the Heath Cantenna) stop turning up the mic amplifier gain but, instead, back off for safety's sake and "peace of mind," remembering to use the same voice level when using the mic in the future.

Another problem we must not forget: When we see power output on a wattmeter, we have to know that power is being produced on the frequency we want it to be and not showing the additional power of some harmonic or spur. This means we have to use some means to verify that the power is on the specific frequency and not on another frequency/ies... For added peace of mind, this then makes it advisable to monitor the transmitted frequency with another receive with antenna input shorted and watch the S-Meter on that receiver. Cheap and dirty but can provide useful data while adjusting the mic gain to max and then backing off a tad.

Bob — KK5R

On Wednesday, August 12, 2020, 12:15:14 PM EDT, Arv Evans <arvid.evans@...> wrote:


Most ham radio systems seem designed for close-talking the microphone.
Some non-ham systems are designed for full-room pickup of audio.  This is 
probably not good for ham radio because it brings in a lot of room echo or 
road-noise if mobile.  

Yes, many in this group have experimented with powered microphones.   The 
result can be good or bad.  You need to know how the modulation circuitry 
works and you need to have some way to monitor the output waveform to 
insure that you are not over-driving the audio input and modulation circuits.
Over-driving the sideband modulation circuit can result in many harmonics 
of the audio frequency, and harmonics of the RF frequency being present in 
your transmit signal.  

Arv
_._



On Wed, Aug 12, 2020 at 6:42 AM Chuck Eglhaut <ceglhaut@...> wrote:
Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


iz oos
 

As for my understanding a mic preamp is not a solution, nor shouting into the mic is. The issue Is similar to listening without an agc. Sometimes you need to pump up the radio untill a huge signal force you to turn it down to avoid distortion. The same applies to the mic input. What is useful in an agc at the mic level. I use a Plessey Vogad chip and a potentiometer to have exactly 10w ssb Pep output on 40 and 20m band.


Il gio 13 ago 2020 05:32 AM Bob Lunsford via groups.io <nocrud222=yahoo.com@groups.io> ha scritto:
An old tradition in hamdom where an experimental microphone is tested running a mic preamp circuit is to monitor the output with a voltmeter across the dummy load and start cranking up the gain on the preamp while talking into the mic. When the output peaks out (using a monitor detector as with the Heath Cantenna) stop turning up the mic amplifier gain but, instead, back off for safety's sake and "peace of mind," remembering to use the same voice level when using the mic in the future.

Another problem we must not forget: When we see power output on a wattmeter, we have to know that power is being produced on the frequency we want it to be and not showing the additional power of some harmonic or spur. This means we have to use some means to verify that the power is on the specific frequency and not on another frequency/ies... For added peace of mind, this then makes it advisable to monitor the transmitted frequency with another receive with antenna input shorted and watch the S-Meter on that receiver. Cheap and dirty but can provide useful data while adjusting the mic gain to max and then backing off a tad.

Bob — KK5R

On Wednesday, August 12, 2020, 12:15:14 PM EDT, Arv Evans <arvid.evans@...> wrote:


Most ham radio systems seem designed for close-talking the microphone.
Some non-ham systems are designed for full-room pickup of audio.  This is 
probably not good for ham radio because it brings in a lot of room echo or 
road-noise if mobile.  

Yes, many in this group have experimented with powered microphones.   The 
result can be good or bad.  You need to know how the modulation circuitry 
works and you need to have some way to monitor the output waveform to 
insure that you are not over-driving the audio input and modulation circuits.
Over-driving the sideband modulation circuit can result in many harmonics 
of the audio frequency, and harmonics of the RF frequency being present in 
your transmit signal.  

Arv
_._



On Wed, Aug 12, 2020 at 6:42 AM Chuck Eglhaut <ceglhaut@...> wrote:
Trying to get a little extra out of my signal. I purchased a Astatic D-104m. Has anyone tried a power mic on uBitx ?


Dean Souleles
 

Hi Chuck - 

For what it is worth I have a V5 and and never seen the need for a power mic or additional gain.  The mic I use is this one -

https://www.amazon.com/gp/product/B008CLIB5K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I mostly work 20 and 40 meters and I have worked stations all over Europe and much of America from my QTH in Virginia.  I get consistently good audio reports.

Dean
KK4DAS


Bob Lunsford
 

Looks good. Just ordered one. Price is right, too. Thanks.

Bob — KK5R

On Thursday, August 13, 2020, 2:28:30 PM EDT, Dean Souleles <dsouleles@...> wrote:


Hi Chuck - 

For what it is worth I have a V5 and and never seen the need for a power mic or additional gain.  The mic I use is this one -

https://www.amazon.com/gp/product/B008CLIB5K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I mostly work 20 and 40 meters and I have worked stations all over Europe and much of America from my QTH in Virginia.  I get consistently good audio reports.

Dean
KK4DAS


Ashhar Farhan
 

There is a simpler way to do this. See the mic amp in the attached screenshot. The mic gain is set by the ratio between the 1K collector load and the 47 ohms emitter degeneration resistor (R63). Out of the box, the gain is 1000/50, approximately 20. If you add a 10 ohms in parallel to that, the gain will jump to 1000/10, about 100. 
I would warn you against too much gain as Arv had pointed out. It can pick up weird stuff and splatter the band.
I was once running a modulator with full throttle and monitoring it on a receiver. I kept  getting these chirps that I figured were from a nearby smps. Nothing cured it, at night they vanished. But the next morning they were back. I thought it must be somthing the neighbours were turning on in the night. As i sat contemplating it, i heard the chirp again! I didn't have my headphones on!! I ran out and traced it to a nest of sparrows on the ledge outside. The mic was picking it all up though it was too soft for me to register.
Look out for the birds and not the birdies.

On Fri 14 Aug, 2020, 7:58 AM Bob Lunsford via groups.io, <nocrud222=yahoo.com@groups.io> wrote:
Looks good. Just ordered one. Price is right, too. Thanks.

Bob — KK5R

On Thursday, August 13, 2020, 2:28:30 PM EDT, Dean Souleles <dsouleles@...> wrote:


Hi Chuck - 

For what it is worth I have a V5 and and never seen the need for a power mic or additional gain.  The mic I use is this one -

https://www.amazon.com/gp/product/B008CLIB5K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I mostly work 20 and 40 meters and I have worked stations all over Europe and much of America from my QTH in Virginia.  I get consistently good audio reports.

Dean
KK4DAS


Tsackett59@...
 

How did you wire this nic? Did you put the four pin connector on the radio chassis,  or convert the mic to the 3.5 mm?


Bob Lunsford
 

Hello Ashar:

I hardly ever overdrive a microphone. I hold the mic next to my cheek with the mic element pointing away from me to avoid transmitting breathing noises. I rather replace the "new" mic's connector with one not used when I bought the complete kit. I also prefer not modifying the radio and its circuitry in any way, keeping it as "original" as possible. This is insurance that no sudden/unintentional damage is done which often is unnoticed at the moment it is done and leaves me scratching my head for an unwanted waste of time. Therefore, I'll replace the "new" mic's plug.

I have opened up the V6 complete kit mic eletret element's hole to 1/8-in for better modulating the element. I also removed a small cap across the eletret (of unknown value) to improve the mic level and to avoid suppressing the higher frequencies (the 'esses' and 'zed sounds.)  Silibants (voiced and unvoiced hissing sounds) are necessary for "understandability" in English and can be proved by listening to voices on a home stereo by turning up and down the bass and treble controls. Higher trebles and lower bass sounds are best for communication (in English)  instead of trying for high fidelity.

I like the looks of the Amazon mic and think it will be comfortable in my hand. It is something to try and see how it compares with the mic provided in the complete kit. The box provided with the complete kit is what I really wanted and appreciate, not so much the mic. In fact, I built the mic when I got the V4 a couple of years ago with no problem and the one provided with the V6 complete kit is fine and usable proved by comments received from a group I communicate with on 75M several times a week.

I am not a hacker — playing with the mic options is more along my line now. After building a complete repeater and most of Heath's ham radio kits, I have all I want of getting into circuitry outside of necessary repairs. After working in electronics so long, making it a hobby is not, for me, all that easy where I strictly want it now as a hobby. (I also play with antennas.)

I love the plug-and-chug aspect of HF Signals "kits" and operating the V6 is part of the pleasure. Thanks for your engineering and design efforts with the great little rig.

Bob — KK5R

On Friday, August 14, 2020, 12:47:00 AM EDT, Ashhar Farhan <farhanbox@...> wrote:


There is a simpler way to do this. See the mic amp in the attached screenshot. The mic gain is set by the ratio between the 1K collector load and the 47 ohms emitter degeneration resistor (R63). Out of the box, the gain is 1000/50, approximately 20. If you add a 10 ohms in parallel to that, the gain will jump to 1000/10, about 100. 
I would warn you against too much gain as Arv had pointed out. It can pick up weird stuff and splatter the band.
I was once running a modulator with full throttle and monitoring it on a receiver. I kept  getting these chirps that I figured were from a nearby smps. Nothing cured it, at night they vanished. But the next morning they were back. I thought it must be somthing the neighbours were turning on in the night. As i sat contemplating it, i heard the chirp again! I didn't have my headphones on!! I ran out and traced it to a nest of sparrows on the ledge outside. The mic was picking it all up though it was too soft for me to register.
Look out for the birds and not the birdies.

On Fri 14 Aug, 2020, 7:58 AM Bob Lunsford via groups.io, <nocrud222=yahoo.com@groups.io> wrote:
Looks good. Just ordered one. Price is right, too. Thanks.

Bob — KK5R

On Thursday, August 13, 2020, 2:28:30 PM EDT, Dean Souleles <dsouleles@...> wrote:


Hi Chuck - 

For what it is worth I have a V5 and and never seen the need for a power mic or additional gain.  The mic I use is this one -

https://www.amazon.com/gp/product/B008CLIB5K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I mostly work 20 and 40 meters and I have worked stations all over Europe and much of America from my QTH in Virginia.  I get consistently good audio reports.

Dean
KK4DAS


Dean Souleles
 

Hi,

I used a four pin connector on the chassis. In my case, I was using an enclosure from amateurradiokits that came with the connector.

That said, it would be simple enough to wire up a 3.5 mm plug.

Dean