Re: VU2ESE Agc circuit

#27868

Jerry,

The LDRs that you are looking for are the ones with the lowest ON (ie; lit-up bright resistance) resistance.

The Bitx volume control pot is a 10k unit so if you are going to shunt the audio signal around the pot you will need an LDR with a ON resistance lower than 10k. Have a look on Ebay and you will see a number of LDRs for sale. The trick is to find and read an LDR spec sheet and chose an LDR type with low ON resistance. Here are some I found:

GL5528 10 - 20k so too high
GL5516 5 - 10k in the ballpark but a bit high
GL5506 2 - 5k this looks like the one to go for

Check out Ebay the GL5506 sell for US$0.99 for 20 pieces.

Shop around you may do better.

Regards,

Peter VK1XP

Show quoted text

On 07-06-2017 23:47, ohwenzelph via Groups.Io wrote:
Follow up:
Ok, the 5-2-2017 revised schematic in the wiki makes it clear where to
put the agc circuit (instead of just audio in & audio out. "splain it
to me like I'm 5 please") Built per the schematic(ignoring the photo
in the mod blog) and put where it is actually supposed to be, the
sound actually gets thru!!!! [I do not understand this electronics
stuff... sigh..]
There was a buzz but I had alligator clip wires all over the place, so
forgiving that.
Will try the vk3ye one, sounds like there are a large variety of
LDRs.. so results may vary?
Did try the anti hiss mod in the "tips and mods" with 'NOTE: NOT
Bitx40 schematic', with 0.01 and 10k from pin 5 to pin 8 of the lm386,
but it did not work for me and added a loud 10k hz tone.
Sent from my iPad
Links:
------
[1] /g/BITX20/message/27811
[2] /mt/5155110/236039
[3] /g/BITX20/post
[4] /g/BITX20/editsub/236039
[5] /g/BITX20
[6] /static/tos
[7] /g/BITX20/leave/defanged

Re: Baofeng microphone mod for BITX

Cesar

#27867

it is same ground. I have troble with the jack connector...

thanks

Re: Baofeng microphone mod for BITX

Joe Puma

#27866

开云体育

Do a test on ptt ground and mic ground..see if its same ground is my guess.

?

Show quoted text

From: [email protected] [mailto:[email protected]] On Behalf Of Cesar
Sent: June 7, 2017 10:37 AM
To: [email protected]
Subject: Re: [BITX20] Baofeng microphone mod for BITX

?

So if you have 4 wires how do you put that to a 3 pin male jack?
do you share mic and ptt ground wires? Is this gonna work?

thank you

Re: Struggling with tuning clicks and birdie sounds

Dimitar Pavlov

#27865

Hi all,

Before, I have the same problem with other transceivers, with various DDS, and with LED/OLED displays.

The tuning clicks, are the software problem, connected to refreshing frequency for display,

reading frequency for the rotary encoder and other refreshing frequencies in arduino code (update frequency to Si570/Si5351/AD9851 ...).

To resolve this problem need to optimize code, and implement some wait()/delay() functions.

(many features - many clicks ..., simple code - no clicks).

The QRP transceiver is just QRP transceiver - not need to make coffee , and read news papper ...

Good idea is to use separate power source (2 or 3 pcs LM7812 / 7805 / 7806 for DDS, receiver and other ...

(Birdie sounds are harmonics problem with DDS, and it is not resolving problem. Transceivers also have birdies in other frequencies,

but Your band plan includes only one/two of them.)

73!

On Thursday, June 8, 2017 12:42 AM, Dr Fred Hambrecht <AAR4MI@...> wrote:

I have braided both the tuning and volume control wires with good results,

plus it looks better.

v/r

Fred W4JLE

Show quoted text

-----Original Message-----

From: [email protected] [mailto:[email protected]] On Behalf Of Allard PE1NWL

Sent: Wednesday, June 7, 2017 07:39

To: [email protected]

Subject: Re: [BITX20] Struggling with tuning clicks and birdie sounds

It seems there is a huge variability between various BITX40 radios, and

there are various points where improvements may help.

In my particular case, I achieved the greatest tuning click reduction just

by using shielded wires to and from the volume potentiometer.

73 Allard PE1NWL

Re: Quality speaker mic with minimal modding

Cesar

#27864

But this is a dinamic microfono right? I guess it will get too much power as the board is designed to put volts on a electret mic...
nice mic for the price anyway?

Calling all Midwesterners.

#27863

Everyone else is getting called out and so should we. We make up the heartland of this country. So let's hear from ya.
de KG5KYJ, John, Oklahoma city, Central time zone. 18' NVIS Dipole. 24 Volt BITX40.

Re: Quality speaker mic with minimal modding

#27862

Thanks for the reply Phil. ?So you tried both the mike as is and with the bitx supplied mic element? And you saw no difference between the two? ?

Was the wiring of the jack to the bitx40 straight forward?

Re: IRF510- Temporary replacement?

#27861

Datasheet says a BS170 is good for 350mw dissipation max.
We normally set RV1 for bias into the IRF510 for a quiescent drain current of 100ma, which means the IRF510 is dissipating 12v*0.1a = 1.2 Watts.
So would cook that BS170 in seconds.
I'd back off on the bias for a BS170 drain current of 10 or 15 ma
Then monitor the BS170 drain current while turning up R136 and giving it some audio,?
keep the drain current below 50ma while transmitting if you are brave.
Maybe 25ma max if not so sure.

If it's working right, that amp might be 50% efficient.
With 50ma it is drawing 12v*0.050a = 0.6 watts from the power supply.
If half of that goes out the antenna, then 0.3 watts (300mw) is heating up the BS170.

Not that I know anything much about RF amps.
But I do have a handle on some bottom rung thermodynamics.

Jerry, KE7ER

Show quoted text

On Wed, Jun 7, 2017 at 05:29 pm, Ryan Flowers wrote:

My thought would be to turn down r136 so that the final doesn't get driven hard at all, and put in a smaller final like the BS170 that I have.

?

Re: cw speed

#27860

Good advice from everyone!

When I was learning, while driving I used to read boards in my mind in morse "did dah dah" sounds!

As Dan said practice till you hear all the birds and squirrels in morse! 

Raj

Show quoted text

At 07-06-2017, you wrote:
Hey Terry,


Keep it up Terry and PRACTICE,PRACTICE, practice, practice, .......

73
Dan
HK4DEI

Re: IRF510- Temporary replacement?

#27859

Thank you Farhan and Jerry. Clearly I am out of my element here. My thought would be to turn down r136 so that the final doesn't get driven hard at all, and put in a smaller final like the BS170 that I have. But I don't know what impact that'll have elsewhere in the circuit or how I would compensate for that. Nor do I know how to use the driver as the PA. I'm hoping to use this as a stepping stone for more knowledge and insight into how PA's work. Thanks again for the assistance.?
--
Ryan Flowers W7RLF

?

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

Re: Baofeng microphone mod for BITX

Cesar

#27858

My problems are due to bad connections. Baofeng uses very poor quality wires and i can see copper trhough plastic!! I have to rewire it. It is going to work i guess as i have checked that ground is the same for mic a ptt on the pcb

ttanks
?

Re: uBITX - A reboot of the old BITX

[email protected]

#27857

Thanks Martin,
I'm told, though, that layout is quite different from Farhan's, using a different amplifier, some questionable spacings between wires and ground planes, all through hole, etc. Would be REALLY nice to simply be able to purchase PCBs

Re: Struggling with tuning clicks and birdie sounds

#27856

I have braided both the tuning and volume control wires with good results,
plus it looks better.

v/r
Fred W4JLE

Show quoted text

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Allard PE1NWL
Sent: Wednesday, June 7, 2017 07:39
To: [email protected]
Subject: Re: [BITX20] Struggling with tuning clicks and birdie sounds

It seems there is a huge variability between various BITX40 radios, and
there are various points where improvements may help.
In my particular case, I achieved the greatest tuning click reduction just
by using shielded wires to and from the volume potentiometer.

73 Allard PE1NWL

Re: Quality speaker mic with minimal modding

philip yates

#27855

Thats the mic I use, have tried it with the supplied insert that come with the Bitx, no difference.

Phil - G7BZD

Show quoted text

On Wed, Jun 7, 2017 at 7:51 PM, <davidzdeb@...> wrote:

Has anyone tried this one?:

Re: Struggling with tuning clicks and birdie sounds

#27854

Thanks Willy,
will try that as soon as weather allows.
Due to living in the center of Berlin sadly i can only put up temporary antenna in some park or similar
and had thus only tested my build with dummy load so far.

vy 73 Philipp DJ4MU

Re: Europe to States BitX QSO

#27853

Andy,

Your antenna is apparently quite effective! ? Can you describe it? ?
Dimensions? ? How high at the feed point? ? How many radials? ?Roughly how much gain over a dipole does a distant station see? ?Is this mostly due to straight antenna gain or a matter of launch angle??

Jerry, KE7ER

Show quoted text

On Wed, Jun 7, 2017 at 01:12 pm, Andy wrote:

My rig is BITX40, about 7w out + 2 phased verticals.?
9a3jh Andy

?

Re: Baofeng microphone mod for BITX

#27852

So if you have 4 wires how do you put that to a 3 pin male jack? do you share mic and ptt ground wires? Is this gonna work?

you have 6 connectors in total on the 2 stereo plugs but only 4 wires going into the Baofeng mic from those connectors.

They all share one common ground on the 2.5mm plugs tip.

this works for me but i'm not sure if it's responsible for the noise problem i have at the moment .

so connections are:
3.5mm:
Tip - NC
Ring - Mic -red
Sleeve - PTT - black

2.5mm:
Tip - common ground (spkr/mic/PTT) -white
Ring - NC
Sleeve -SPKR - green

hope that clarifies it.

Re: Europe to States BitX QSO

Andy

#27851

Thanks Paul,
CW signal from W1LY was really good, real 579. I am sure that I can copy -10db signals in same conditions :)
SSB was not so strong but readable, because my antennas are optimized for cw part of 40m band. Today morning on my Sunrise I had also good CW reports from USA east coast RBN's (reverse beacon network).
During winter time will probably be much easier to make QRP/QRP contact NA – EU.

Again, thank you Willy for nice QSO's!

My rig is BITX40, about 7w out + 2 phased verticals.
If any other HAM station like to try CW qso we can arrange sked next days.

73 & GL with BITX Dx-ing,

9a3jh Andy

Re: 300Km with a bicycle and my Bitx40

#27850

Julien,
A very nice article! Too bad the radio could not be fixed while en route.

Re: Handheld Mic w/ PTT for BITX40

#27849

Which pins are used for the speaker output?