Re: Low mic gain, was, show your mic

Gordon Gibby
 

Max, your web site is very impressive!   great work!!  


On Apr 22, 2018, at 23:12, Gordon Gibby <ggibby@...> wrote:

Multiple people have explained how to decrease the emitter resistor in the mic amplifier stage to incrase the gain.   I didn't think of that, so just built a 1-transistor preamp for it and was quite happy.    Also had to do that for another transceiver I owned 30+ years ago.   Simple enough to do.    


Also be careful, the average power output measured by an analog scale is far far less than the peak if if you push the apparent average way up there....all you'll be doing is pushing the peaks into non-linear splattering.   


the older hams used to use oscilloscopes on their outputs so they could actually SEE when they were overmodulating.   Impressive amount of concern, I would say!    But I did get two of those type scopes for relatively cheap on ebay....use them to show people what signals look like in license classes occasionally.


that's ham radio!

​it isn't meant to be easy



gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of Gordon Gibby <ggibby@...>
Sent: Sunday, April 22, 2018 11:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Low mic gain, was, show your mic
 

Whenever you wish to FUND that effort, you'll easily find people who will be willing to get on your payroll!!


If you look at that photo, there's a "clue" in that one terminal connects to the CASE.    And the legend that I always saw on the similar photo here:   http://www.hfsignals.com/index.php/2017/11/23/wiring-up-the-bitx40/   is also a good giveaway.


This tutorial is another explanatory bit of information (about the first one that popped up in a google search for electret mic pinout)   https://components101.com/electret-condenser-microphone


That's ham radio!


gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of MAX <max@...>
Sent: Sunday, April 22, 2018 10:57 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Low mic gain, was, show your mic
 

Interesting.  That picture has no indication as to which is positive and which is negative.  If I didn’t already know that the upper right connection was ground the picture would be useless.  I am probably offending some people but I’m about fed up.  All of the correct information needs to be gathered in one place.  Call it a manual or whatever you want but  someone who knows needs to take the time and put forth the effort to put it together.  And then all the incorrect information needs to be removed from the web. 

 

Not a happy camper.

 

Max K 4 O D S.

 

I've Never Lost the Wonder.

 

Antique Electronics Site: http://www.angelfire.com/electronic/funwithtubes/

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Mvs Sarma
Sent: Sunday, April 22, 2018 1:57 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Low mic gain, was, show your mic

 

if i recollect , a reverse polarity was also responding for voice but verey very lowand distorted.


Regards
MVS Sarma
 

 

On Sun, Apr 22, 2018 at 10:15 PM, MAX <max@...> wrote:

Hi sarma.

 

I’m sure I have the polarity correct.  Someone on this list posted a drawing showing how to identify the negative terminal and I wired according to it.  I think the electret mic wouldn’t work at all if polarity were reversed.  What is being powered is an  F E T source follower.   I think I shouldn’t have to raise my voice to get 5 watts output on 40 meters.

 

Regards.

 

Max K 4 O D S.

 

I've Never Lost the Wonder.

 

Antique Electronics Site: http://www.angelfire.com/electronic/funwithtubes/

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Mvs Sarma
Sent: Sunday, April 22, 2018 3:44 AM
To: BITX20@groups.io
Subject: Re: [BITX20] show your mic

 

Max,

 please check whether the mic body is connected to chasis ground.

i mean the positive bias voltage for mic should come on independent pin and NOT to the body pin of the eletret element.

In case you are using a dynamic mic, perhaps we need more gain and your need to shout appers logical.

regards

sarma

vu3zmv


Regards
MVS Sarma
 

 

On Sat, Apr 21, 2018 at 11:27 PM, MAX <max@...> wrote:

Speaking of mics, I have to raise my voice almost to the level of shouting to get 5 watts out on 40 meters.  Is this normal or should I look for a problem?

 

Regards.

 

Max K 4 O D S.

 

I've Never Lost the Wonder.

 

Antique Electronics Site: http://www.angelfire.com/electronic/funwithtubes/

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Mvs Sarma
Sent: Saturday, April 21, 2018 7:17 AM
To: BITX20@groups.io
Subject: Re: [BITX20] show your mic

 

I had grabed a taperecorder mic with 3.5mm mono pin.
 replaced the cable with 2+shield.had a small pushed switchmounted and wired.
 repalced the 3.5mm momo pin to stereo pin. Here is a image of my mic.The pp9 battery helps to imagine the mic size.
regards
 sarma
 vu3zmv

 

 

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