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Re: Handheld Mic w/ PTT for BITX40

 

A couple of Quid/Bucks for a CB hand microphone, But a DC blocking cap on the mic lead to it from the BITX-40 and away you go .. It couldn't be any problem easier, All this talk of buying boxes and switches to make your own when it's far cheaper , Easier to buy a CB type one ..


On Thu, 23 Feb 2017 at 6:00, Ryan Flowers
<geocrasher@...> wrote:

Hey everyone, I'm looking at options for a "real" microphone and ran across this one:

It's got an 3 wire electret mic, not sure about the circuit it has. Will I need to bypass most of that to use it with the BITX40? Or should I gut it and put in the mic that came with the BITX40? Thanks a lot for any recommendations.?

--
Ryan Flowers KC7RYS?
Re: Handheld Mic w/ PTT for BITX40

 

A very long time ago, as a repeater user, I had a bell systems Trimline handset, and with very minor additions to the old HeahKit HW202 2 meter rig, it (the Trimline) worked as a mic, with DTMF pad.? If I remember right, I put a small pushbutton in the side, and the rest of the handset was unaffected- and I put 12V on the mic line.? It worked really well.

My point being that the telephone handset may be a nice speaker/mic.? It would benefit from the electret, but the speaker element probably would be very well suited.? And a PTT switch might be possible if ground are common- leaving one conductor open.

The RJ11 jack would need to be salvaged from the base

73
Larry KB3CUF (ex WB3INC)

On Thu, Feb 23, 2017 at 12:36 PM, Ryan Flowers <geocrasher@...> wrote:

Thanks everyone, I sincerely appreciate the responses! Jack, I hadn't even considered the weight issue- thanks for bringing it up. I think a 4 conductor telephone cord will solve the problem and I'll just make a nicer looking handheld mic. I'll post what I come up with eventually. I'm still working on the case, too. Thanks again!


--
Ryan Flowers KC7RYS?


Re: Handheld Mic w/ PTT for BITX40

 

Yep, as I scrolled down I saw Jack beat me to it. The telephone cord with four wires, and if you're slick you can put in a chassis mount jack. ?You also got a choice of colors and length with phone cord.
Re: Handheld Mic w/ PTT for BITX40

 

Thanks everyone, I sincerely appreciate the responses! Jack, I hadn't even considered the weight issue- thanks for bringing it up. I think a 4 conductor telephone cord will solve the problem and I'll just make a nicer looking handheld mic. I'll post what I come up with eventually. I'm still working on the case, too. Thanks again!


--
Ryan Flowers KC7RYS?
Re: weak mic audio output,

Michael Davis
 

¿ªÔÆÌåÓý

There is an inexpensive, amplified adjustable ?electret mic on Amazon. Not sure if/how it would work. See??

Sent from Mike's iPad WA1MAD

Sent from Mike's iPad WA1MAD
Re: Handheld Mic w/ PTT for BITX40

 

I *just* bought (via eBay) two 'Beofeng' microphones.
They were US$2.89 each. One for my Beofeng (hey, it's cheap and works), and one to cut up for little home-brew rigs.

One worked perfectly, the other had a solder problem with the electret (easily fixed, see: ).

These are handi-talkie mics, and speaker-mics to boot - so, you can cut off the little dual-plug and wire it up how you want.
PTT & mic only, or add the speaker in.

I purchased eBay item: 322313252027, but there at least a dozen other sellers.

Here's the fix to the one that didn't work - I just shorted two solder points - apparently the trace is bad (do look at the bubbly PCB - I'm not saying this is great quality, but it works):

Mike Yancey, KM5Z
Dallas, Texas
Junk CB radio source for parts

 

Hi

I saw another message about using a mic from a CB radio. There is a lot more that you can use. An old junk CB radio is a great source of parts that you may use on your BITX40 build.

Speaker
Knobs
Pots, maybe
SO239 antenna connector
Mic
Mic jack
Heatsink
Connectors
Meter, older rigs have an analog meter
Power cord maybe with fuse
Possible case
Hardware

I asked around if anyone in the local club had an old CB. Nothing. But one of the guys gave me an old Kenwood TR-7400 from back in the 70s, no tone, no memory. Not sure if it works. It is huge compared to today's radios.Soon to be gutted.?

Randy, K7AGE
Re: Would someone mind explaining to me how the BFO frequency circuit works?

Baruch Atta
 

Are you asking about the BFO in the transmitter circuit?

The BFO in the transmitter circuit hetrodynes the 4.9-5.0 MHz single sideband signal with a 12.0 (approx) MHz BFO signal, giving 12+5=17 and 12-5=7 MHz output.? The BitX uses the 7 MHz signal which is amplified and transmitted.?

See the March 2017 QST for a nice article on the original use of this method in the antique radios section.?

On Thu, Feb 23, 2017 at 9:02 AM, <KD2BBW@...> wrote:

I know a bit about electronics but not enough apparently!
Re: Handheld Mic w/ PTT for BITX40

Baruch Atta
 

I used a mic and jack from an old CB.? I replaced the mic element with the element supplied with the BitX.? I used the jack from the CB.?

On Thu, Feb 23, 2017 at 10:45 AM, Jason N3YUG <jbr13@...> wrote:

Hey Ryan,? I took one of my old Yaesu HT speaker mics, and rewired it for the BITX40,? It has a Electret?mic element in it already, and a PTT.? I see on you can pic up a speaker mic for $6-$15.? I say go for it, I like having the coiled cord also!


Jason

N3YUG
Re: Handheld Mic w/ PTT for BITX40

Jack Purdum
 

I like a coiled cord, too. However, unlike my base transceiver, when the rig weighs about a pound and I turn around mid-QSO to answer the phone only to see my B40 whiz by my head because of the spring-tension in the cord, that's when I went to a non-coiled cord.

Jack, W8TEE


From: Jason N3YUG <jbr13@...>
To: [email protected]
Sent: Thursday, February 23, 2017 10:45 AM
Subject: Re: [BITX20] Handheld Mic w/ PTT for BITX40

Hey Ryan,? I took one of my old Yaesu HT speaker mics, and rewired it for the BITX40,? It has a Electret?mic element in it already, and a PTT.? I see on amazon.com you can pic up a speaker mic for $6-$15.? I say go for it, I like having the coiled cord also!

Jason
N3YUG
Re: Handheld Mic w/ PTT for BITX40

Jason N3YUG
 

Hey Ryan,? I took one of my old Yaesu HT speaker mics, and rewired it for the BITX40,? It has a Electret?mic element in it already, and a PTT.? I see on amazon.com you can pic up a speaker mic for $6-$15.? I say go for it, I like having the coiled cord also!


Jason

N3YUG
Re: Would someone mind explaining to me how the BFO frequency circuit works?

 

It's all working at about 11.998500mhz. ? Q10 is the oscillator and has some high impedance nodes on the left hand side, poking at it around the base or L5 may either disturb the oscillator or show low level signals that your instrument has trouble with. ?Q11 is an emitter follower to buffer output from the oscillator and drive a strong signal into the transformer without sucking too much power out of the oscillator. ?R104 ensures that even Q11 doesn't load down the oscillator, R104 is apparently getting stuffed with 10k these days instead of 2.2k. ?The little trimmer cap at C103 is not getting stuffed, it was found that by selecting crystals with all the same freq the BFO freq was just about right without any need for adjustment.


On Thu, Feb 23, 2017 at 06:36 am, <KD2BBW@...> wrote:

Also when I measure at L5 I was getting ~12MHz on my counter and when I measure at base of Q10 I was getting ~6Mhz.

?
Re: Would someone mind explaining to me how the BFO frequency circuit works?

 

Q10 is the xtal oscillator with L & C in series, to pull the xtal down a bit to suit LSB.

If you can generate a second frequency from the Si then you can remove Q10 and use Q11 to buffer it to the mixer.

In the meanwhile I'll stick to my analog VFO!

73
Raj

At 23/02/2017, you wrote:

I was wondering more about what the purpose of Q10 and Q11 serve.


What I'm trying to do is take an output from SI5351 and replace the entire BFO circuit so I can easily switch between LSB and USB via software.
Re: Would someone mind explaining to me how the BFO frequency circuit works?

 

Also when I measure at L5 I was getting ~12MHz on my counter and when I measure at base of Q10 I was getting ~6Mhz.
Re: Would someone mind explaining to me how the BFO frequency circuit works?

 

I was wondering more about what the purpose of Q10 and Q11 serve.


What I'm trying to do is take an output from SI5351 and replace the entire BFO circuit so I can easily switch between LSB and USB via software.
Re: Would someone mind explaining to me how the BFO frequency circuit works?

 

After all these years sometimes I get to forget!

You have a carrier frequency which you send to a mixer then mix it with some audio
then you end up with one central carrier and two side bands of audio content.

The carrier is a waste of your power so you take it out and so also the other side band
energy which is a mirror. So your xtal filter does the job and selects one side band.

When this signal is received by you then you need to re-insert the carrier (BFO)
back to make the incoming signal intelligible in audio.

And if you vary your BFO frequency the incoming signal may sound tinny or bassy
depending where your BFO is!

Hope that helps!
---
Raj vu2zap

At 23/02/2017, you wrote:

I know a bit about electronics but not enough apparently!
Re: Flutter Fix

Jack Purdum
 

Quite often the compiler issues a line number that is a long way from where the error is. Because C is a "free form" language, the compiler parses the code as long as the next token that it sees is consistent with the grammar rules. An error that actually happens on line 500 may not cause the compiler to get into the what-the-hell-it-that state until a hundred lines later. If you'd like, send me the source file and I'll see if I can find the error and send it back to you.

Jack, W8TEE


From: John Smith via Groups.Io <johnlinux77@...>
To: [email protected]
Sent: Thursday, February 23, 2017 12:24 AM
Subject: Re: [BITX20] Flutter Fix

Ok, I copied the whole section and replaced the whole section in the sketch. And got the same error. Here is more detail- after turning line numbers it highlights in pink line #617. Here is the line- "void loop(){". This is part of the original code, and it doesn't cause an error in it's original form.
And the latest error message is the same as posted before. Stand by for more details.
This is the whole section I replaced-
? // the tuning knob is at neither extremities, tune the signals as usual
? else if (knob != old_knob){
? ? ?frequency = baseTune + (50l * knob);
? ? ?old_knob = knob;
? ? ?setFrequency(frequency);
? ? ?updateDisplay();
? }
}
So am I still too thick?
Would someone mind explaining to me how the BFO frequency circuit works?

 

I know a bit about electronics but not enough apparently!
Re: Handheld Mic w/ PTT for BITX40

Jack Purdum
 

My mic cost me $0.87 to build from the parts that came with the B40. (See pix.) The mic cord is an old telephone cable from the house phone line that was lying around. While its construction is pretty obvious, details will be in the April, QRP Quarterly. The green stuff is large diameter shrink tubing that I got in a Dayton grab bag...it's so big I never thought I'd find a use for it. You never know...

Jack, W8TEE


From: Richard Andrew Knack via Groups.Io <ihc73scout2@...>
To: [email protected]
Sent: Thursday, February 23, 2017 4:45 AM
Subject: Re: [BITX20] Handheld Mic w/ PTT for BITX40

Why not this one:


Rich
KC8MWG




On Thursday, February 23, 2017 1:58 AM, Ryan Flowers <geocrasher@...> wrote:


On Wed, Feb 22, 2017 at 10:46 pm, John Smith wrote:
Use a small plastic box that feels like a comfortable mic, and put the mic poking out of the face of it, and the button on the side. That one from Banggood has 8 pins. You would only need 4, two for the mic wires, and two for the button wires. And it's just wasteful to buy a mic only to rip it's guts out for a downgrade. ?Look for a small picture hanging parts box in a gift type tool box. Or ask a woman you know for something like that used for cosmetics. Or look for a small project enclosure box that looks like a small radio microphone. Here is an example of someone's photo in the emailed photos folder on this site. Otherwise get the cheapest Baofeng hand mic and hack it. It also has a speaker in it.
?I considered doing that. The biggest thing is that I want one of those mic cables because they coil up, and currently mine does not. Perhaps I just need to find a better cable for the one I have. The coiled cords are $10 everywhere I've looked, and this whole mic is $10. And it's not wasteful if it serves my purpose. I know I'll have to source an 8 pin connector for it- ?else buy a mating 4 pin connector set and replace them, which I could easily do. My concern isn't whether this is a good idea. My concern is- is there any reason it won't work?

--
Ryan Flowers KC7RYS?





Figure04DollarMic.jpg

Re: weak mic audio output,

 

Dwine,

A quick fix? would be a speech processor. Or you could add a bigger heat sink and change the final voltage to 24V and get a
bigger signal!

Raj

At 23/02/2017, you wrote:

Is the grounding of the red wire(calibration)is no help in this situation?



On Thu, 23 Feb, 2017 at 7:49 pm, Raj vu2zap
<vu2zap@...> wrote:
Correction not CW but USB/LSB. Just woke up from a nap!

Yes, you will either need a frequency counter or a commercial Rx or Tcvr.

You can put a short wire from commercial Rx/Tcvr as a pickup near the BITX and tune around 12Mhz to get the BFO carrier beat note in CW.
Tune for ZERO beat and see what you get!

Raj

At 23/02/2017, you wrote:
Hello raj,
How to check bfo frequency?is there a need special instruments?



On Thu, 23 Feb, 2017 at 4:51 pm, Raj vu2zap
<vu2zap@...> wrote:
Check the BFO frequency. 11.9985 MHz.
If you have full power then your signal is fine but if the BFO is off then the voice can sound bassy or tinny.
Maybe thats what was meant by weak audio or simply a weak signal - you are QRP after all!
Raj
At 23/02/2017, you wrote:
i will trace it again john,,that`s what make me wonder during QSO.,they told me i have very weak audio.,
73`



On Thu, 23 Feb, 2017 at 4:21 pm, John Smith via Groups.Io
<johnlinux77@...> wrote:
Ya got me licked. Do you feel like there is not enough audio signal being produced before it goes out to the antenna? If yes, then that's what I would have told you and everyone else. Did you say you changed out the mic? If it's not the drive or or the mic, then it must be a short including a loose connection. Check your different soldered wire connections and trace the connections on the board for those solder joints. Just look at it for anything wrong or smells funny or is missing. When you find it bring it back here.

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