开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. BITX20
  2. Topics

Two little circuit boards for my Bitx40 txcvrs

 

A week or two back somebody was commenting on a chip that does voice compression.? A quick search on AliExpress found a module that uses said chip for a few dollars, so I bought a couple for my Bitx40s.

I figured these boards were a bit bigger!? The coin is about the size of an American quarter.

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?

These modules are very tiny indeed!? There will be no trouble finding room for them in any enclosure.? I will report on how they work in a few days time!

Mike ZL1AXG?
 

I look forward to hearing how they work out for you! As fir removing R1 and R2, just heat up your soldering iron and hold one side of the resistor for a little longer than usual to get it nice and hot, and then do the same to the other side. Hold for 2-3 seconds each. Now while it's hot, quickly move the iron from back to the pre-heated pad, and knock it off the pad with the solder tip. Works every time :)?

--
Ryan Flowers W7RLF

?

?<-- Learn how to go digital on the BITX40
 

开云体育

Any of the usual smd desoldering techniques will do the job, Mike. Hot air source or? solderwick with lots of flux etc.

Bill VK7MX


On 22/11/2017 5:21 PM, Mike Woods wrote:

A week or two back somebody was commenting on a chip that does voice compression.? A quick search on AliExpress found a module that uses said chip for a few dollars, so I bought a couple for my Bitx40s.

I figured these boards were a bit bigger!? The coin is about the size of an American quarter.

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?

These modules are very tiny indeed!? There will be no trouble finding room for them in any enclosure.? I will report on how they work in a few days time!

Mike ZL1AXG?

 

Looks like some research is required on such techniques.

M


On Wed, 22 Nov 2017 at 8:18 PM, William R Maxwell <wrmaxwell@...> wrote:

Any of the usual smd desoldering techniques will do the job, Mike. Hot air source or? solderwick with lots of flux etc.

Bill VK7MX


On 22/11/2017 5:21 PM, Mike Woods wrote:
A week or two back somebody was commenting on a chip that does voice compression.? A quick search on AliExpress found a module that uses said chip for a few dollars, so I bought a couple for my Bitx40s.

I figured these boards were a bit bigger!? The coin is about the size of an American quarter.

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?

These modules are very tiny indeed!? There will be no trouble finding room for them in any enclosure.? I will report on how they work in a few days time!

Mike ZL1AXG?

 

It might be that the presetting that the Rs provide would be adequate.? Perhaps trying one as is would be interesting.
 

Looks like there is a capacitor C5 in series with the mic unless there is a resistor on the other side of the board.?
So to use an electret mic you will have to include a resistor to the mic.

On Wed, Nov 22, 2017 at 7:21 AM, Mike Woods <mhwoods@...> wrote:
A week or two back somebody was commenting on a chip that does voice compression.? A quick search on AliExpress found a module that uses said chip for a few dollars, so I bought a couple for my Bitx40s.

I figured these boards were a bit bigger!? The coin is about the size of an American quarter.

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?

These modules are very tiny indeed!? There will be no trouble finding room for them in any enclosure.? I will report on how they work in a few days time!

Mike ZL1AXG?
 

For a small resistor like that, I use two fine tipped soldering irons, one on each end.
Less heat since it's over very quickly, and can usually pluck the resistor out of there
with the soldering irons instead of just shoving it into some adjacent part.
Find some board you don't care about to practice on.

I use hot air gun a lot when removing IC's, but this often disturbs nearby parts.
I also use lots of hot air when shoveling out advice in this forum.

Jerry, KE7ER


On Tue, Nov 21, 2017 at 11:26 pm, Mike Woods wrote:
Looks like some research is required on such techniques.
?
 

Removing SMD resistors can be done with two soldering irons or with one
soldering iron that has a wide enough tip to bridge both ends of the resistor.
A heat gun can also be used but it is difficult to contain the heat to just one
small component.
_._


On Tue, Nov 21, 2017 at 11:21 PM, Mike Woods <mhwoods@...> wrote:
A week or two back somebody was commenting on a chip that does voice compression.? A quick search on AliExpress found a module that uses said chip for a few dollars, so I bought a couple for my Bitx40s.

I figured these boards were a bit bigger!? The coin is about the size of an American quarter.

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?

These modules are very tiny indeed!? There will be no trouble finding room for them in any enclosure.? I will report on how they work in a few days time!

Mike ZL1AXG?
 

Or the brute force approach:? Cut the Rs in half with a pair of small diagonal cutters.? Desolder if you must.
 

开云体育

Just turn your soldering tip parallel to the length of the SMD.? One iron tip will heat both pads, flip the part off.

Adding solder helps.?? The crappy "earth friendly solder" flows a lot better when you add in old fashioned 60/40.

It usually sticks to the iron, I tap the iron on the bench to get it off.

73's

Mike, WA6ISP


On 11/22/2017 7:14 AM, Arv Evans wrote:
Removing SMD resistors can be done with two soldering irons or with one
soldering iron that has a wide enough tip to bridge both ends of the resistor.
A heat gun can also be used but it is difficult to contain the heat to just one
small component.
_._


On Tue, Nov 21, 2017 at 11:21 PM, Mike Woods <mhwoods@...> wrote:
A week or two back somebody was commenting on a chip that does voice compression.? A quick search on AliExpress found a module that uses said chip for a few dollars, so I bought a couple for my Bitx40s.

I figured these boards were a bit bigger!? The coin is about the size of an American quarter.

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?

These modules are very tiny indeed!? There will be no trouble finding room for them in any enclosure.? I will report on how they work in a few days time!

Mike ZL1AXG? 


-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...
 

FWIW, here's the thread that had this little board:

/g/BITX20/topic/6393762

Also, Simon did a neat little mod simulation for some helpful EQ.

/g/BITX20/topic/6393762

Good EQ and compression should really help this radio.
 

Here's what the EQ should roughly look like:
 

开云体育

The thread for this board is actually here (there was another thread dealing with mic emphasis which this module doesn't do):

/g/BITX20/topic/6374017#34387?
?
The board can be found here on Aliexpress:???


The SSM2167 datasheet can be found here:



Thanks everybody for the suggestions on how to remove the two small SMD resistors.? I am not used to working with such tiny components, but I will give it a go!

A few external components will be needed:

1.? The board runs on 3v-5v. The BITX40 operates at 12v.? I am thinking a simple resistor divider will work given the chip draws 4mA according to the specs.?? A simple resistor to the 12v lines should work (I will try something like 6.8K since resistance of the circuit is around 3K) and then measure voltage.

2.? As noted in one of the comments, bias for the electret mic will be required. I am assuming I can use another resistor to lower the 12v line (copying the circuit in the BITX40 mic connector).

3.? Because of the 20dB (or thereabouts) gain of this chip (it appears the module manufacturer has simply copied the datasheet values) I will need a variable pot on the output (i.e. mic gain control).? I plan to bring this to the back panel of my enclosure.

4.? I will definitely also want a variable pot to control compression on my back panel.? Not sure I need it for the noise gate control.? I will use a trimpot.

I plan to mount the module on a small section of prototype board where I can install off-module components.? Little multi-turn trimpots can be mounted directly on the module for controlling compression (200k) and noise gate (5k).? However, I know amateur ops always want to fiddle with the compression ratio!

I suspect that the junction of pin 6 (with capacitor C3) which is an averaged RMS value of input level could be used to connect (via a resistor) to an arduino analogue input to become a VOX control.? I would like to have a play with this as well to ensure there is enough voltage to be read by the arduino!?? This will need a further mod to my mic (I am using one of those cheap Aliexpress Baofeng mics) as the RX/TX switch is in series with the mic input at present.

73 Mike ZL1AXG
 

Haha, I pasted the wrong link in my post.? Sorry about that!

Can't wait to hear how this works out!
 

Any updates on this project?
 

This is now not going to happen until after Xmas.? The Saltmine has increased my hours. ?

Mike


On Thu, 7 Dec 2017 at 9:15 AM, Arvo KD9HLC via Groups.Io <arvopl=[email protected]> wrote:
Any updates on this project?

 

I ordered the two little circuit boards as well.
Ken KM4NFQ
 

On Wed, Nov 22, 2017 at 1:21 AM, Mike Woods <mhwoods@...> wrote:

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?


Hello Mike,

A Hot-Air Gun seems to be the recommended way to remove SMDs from a PCB.
But please be careful. I recently bought one, and I have toasted a couple
of "practice PCBs" while learning how to use it. I still have some more
practice to do before I feel comfortable using it.

Regards,
Ken, KM4NFQ
Dale Brooks KG7SSB
 

When you use a hot air gun for soldering or removing parts you stand the risk of causing other close parts to move around. I just use my soldering iron and rotate the heat from one end of a component to the other and finally it becomes hot enough to move around so just flip it off the pads with the iron tip and the part will be detached. I've never lifted a pad or damaged any board using this method so far. Good Luck,,, Dale

On Fri, Dec 15, 2017 at 2:43 PM, Ken KM4NFQ <km4nfq@...> wrote:
On Wed, Nov 22, 2017 at 1:21 AM, Mike Woods <mhwoods@...> wrote:

Any ideas for how to remove the tiny resistors R1 and R2 (about 1mm in length and .5mm wide) so that I can use potentiometers instead? ?


Hello Mike,

A Hot-Air Gun seems to be the recommended way to remove SMDs from a PCB.
But please be careful. I recently bought one, and I have toasted a couple
of "practice PCBs" while learning how to use it. I still have some more
practice to do before I feel comfortable using it.

Regards,
Ken, KM4NFQ
 

You may well be the first to try these out.? It is madness season in ZL with all projects having to be finished before Xmas and long summer vacation time!

Mike ZL1AXG


On Sat, 16 Dec 2017 at 7:53 AM, Arvo KD9HLC via Groups.Io <arvopl=[email protected]> wrote:
I ordered the two little circuit boards as well.

1 - 20 of 23