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Re: Mic doesn't work in bitx40 #bitx40

 

The mic may be bad or connected reverse polarity.. pay attention to that!

At 17-05-18, you wrote:

Hello everyone..

I have some problem with my mic pre-amp.. The voltage from 4.7KOhm resistor suddenly drop to 0.130-0.132Volt after I connect it to the mic electret..

Is this normal?

I've put my oscilloscope on the 1uF capacitor to observe the change of the frequency, but it doesn't even display any change when I said or scream in front of the mic. What could be the problem?

Need help here..
Re: Mic doesn't work in bitx40 #bitx40

 

Are you using an electret condenser mic ?

If you connect a dynamic mic then what you describe is correct. The design is for electrets.

Raj

At 17-05-18, you wrote:

Hello everyone..

I have some problem with my mic pre-amp.. The voltage from 4.7KOhm resistor suddenly drop to 0.130-0.132Volt after I connect it to the mic electret..

Is this normal?

I've put my oscilloscope on the 1uF capacitor to observe the change of the frequency, but it doesn't even display any change when I said or scream in front of the mic. What could be the problem?

Need help here..
Re: Core for Output Transformer

 

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Bill, are you still using the IRF510¡¯s and if so how many turns for the primary and secondary windings? While experimenting last night I noticed that T11 was heating up and power out would drop somewhat.?

Skip Davis, NC9O

On May 16, 2018, at 22:03, K9HZ <bill@...> wrote:

Actually I just tried/ wound a BN61-002 and it seems to be the winner so far.? Doesn¡¯t heat up at full power and is extremely wide banded¡­

?

?

Dr. William J. Schmidt - K9HZ

?

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From: [email protected] [mailto:[email protected]] On Behalf Of Nick VK4PLN
Sent: Wednesday, May 16, 2018 8:09 PM
To: [email protected]
Subject: Re: [BITX20] Core for Output Transformer

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THanks GLen.

I was about to suggest using dual bn43-202 for the output and power feeding... should be easy enough to fit in the existing board...

Wonder if it will be better to do this or a bifilar wound 10T FT50-43 for feeding in the power?

73 Nick VK4PLN

?

Virus-free.

Re: Using IRF530 outputs and 2N3553 drivers in ubitx

 

The BFU590 is a current device?with similar specs.?

--
Karl Heinz - K5KHK
Re: share your BITX success stories

Daniel Conklin
 

I agree too!? I have been making contacts with special events stations and DX on 40 meters SSB.? My first contact was the Marconi Birthday Memorial station in Cape Cod, then the Indy Speedway F1 race day station.? Since I sole my FT=817 two years ago I've only been using CW with home built QRP transmitters, so it's a real treat to be able to make some voice contacts with a radio that I may not have designed and built, but at least I assembled it.??
- Dan , W2DLC
Re: Mic doesn't work in bitx40 #bitx40

 

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Are you using the mic element that came with the UBITX? If you are did you wire it up correctly, there is a positive/audio pin and a negative/ground pin connected to the case of the element. You can see the case/pin connection with a magnifying glass on some elements it is only a small trace that can be measured with your ohm meter.?

Skip Davis, NC9O

On May 17, 2018, at 05:46, qonita.salimah@... wrote:

Hello everyone..

I have some problem with my mic pre-amp.. The voltage from 4.7KOhm resistor suddenly drop to 0.130-0.132Volt after I connect it to the mic electret..?

Is this normal?

I've put my oscilloscope on the 1uF capacitor to observe the change of the frequency, but it doesn't even display any change when I said or scream in front of the mic. What could be the problem?

Need help here..
Re: uBitx

 

Nice info, but i fear same device if bought from ebay could well be a fake "wx" device (tda2822)

Regards
MVS Sarma
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On Thu, May 17, 2018 at 4:57 PM, alans77 via Groups.Io <alans77@...> wrote:
An unexpected bonus from using the NJM2037 is a significant reduction in receive audio distortion. Highly recommended.?
Alan N4AYE


Re: uBitx

 

An unexpected bonus from using the NJM2037 is a significant reduction in receive audio distortion. Highly recommended.?
Alan N4AYE
Re: share your BITX success stories

 

I am having a ball with mine, I get around 10 watts on 80 and 40 meters. I am making contacts up to around 700 miles from a fan dipole at 35 feet (10 meters or so). I am putting the finishing touches on my enclosure, a re-purposed Cobra 148 CB case, and am enjoying the whole experience. I am going to attempt to do Howard's mods for leveling out the power on the upper bands and add the necessary cabling for digital.

I have also uploaded the KD8CEC firmware, and must say it is a pleasure to use. Thanks to Ian for his hard work!

73 de WS4JM
Re: #ubitx #ubitx-help #ubitx-help #ubitx

 

Happy!!!
I replaced the diode and it works again???
Re: Using IRF530 outputs and 2N3553 drivers in ubitx

 


They come up as obsolete



On Wed, May 16, 2018 at 07:54 pm, Rahul Srivastava wrote:
Hi!
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I feel we should give BFG591 a try, they are modern devices , easily available with online suppliers and more compatible with the SMD construction of uBitx. There is plenty of headroom where Ft is concerned will work on 6 and yes I have seen it being used as driver in some designs.
?
73
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Rahul VU3WJM??
Re: Core for Output Transformer

 

Getting there, I reckon do the mpsh10 before the RD16hhf1. I can do the rd16RD16 first, and we can get 2 sets of data..
I have tomorrow off work, and plan to play radio all day.
73 Nick VK4PLN
Mic doesn't work in bitx40 #bitx40

 

Hello everyone..

I have some problem with my mic pre-amp.. The voltage from 4.7KOhm resistor suddenly drop to 0.130-0.132Volt after I connect it to the mic electret..?

Is this normal?

I've put my oscilloscope on the 1uF capacitor to observe the change of the frequency, but it doesn't even display any change when I said or scream in front of the mic. What could be the problem?

Need help here..
Re: Core for Output Transformer

 

ps I didn't fit the MPSH10's in this test.
vk3pe



On Wed, May 16, 2018 at 11:51 pm, Glenn wrote:
Hi Nick, yes close to AUD$11 here plus postage.

I did a few tests on my uBITX today.

It started off totally stock. I measured the power out (CW mode) and then added the 220pF caps and some other changes as below.
Max. output on 10M band was 6W. The R97,98 mods were part of Ashhars mods. Since I had already fitted the 220pF at that stage, I didn't remove the 220pF caps and do all his mods.

Glenn





On Wed, May 16, 2018 at 10:43 pm, Nick VK4PLN wrote:
Only problem is the 002 is 10x the price of the 202....
Re: Core for Output Transformer

 

Hi Nick, yes close to AUD$11 here plus postage.

I did a few tests on my uBITX today.

It started off totally stock. I measured the power out (CW mode) and then added the 220pF caps and some other changes as below.
Max. output on 10M band was 6W. The R97,98 mods were part of Ashhars mods. Since I had already fitted the 220pF at that stage, I didn't remove the 220pF caps and do all his mods.

Glenn





On Wed, May 16, 2018 at 10:43 pm, Nick VK4PLN wrote:
Only problem is the 002 is 10x the price of the 202....
Re: #ubitx #ubitx-help #ubitx-help #ubitx

 


If you build per the plans and don't happen to have a fuse on the power supply, there is no reverse polarity protection.
Search for "reverse polarity" in this forum to see the various threads.
Here's one:? ?/g/BITX20/message/35353

Once you pop the diode, you have the full reversed supply to the board.
The only way to be lucky here would be if you had a really wimpy supply that was unable to blow the diode open,
or you happened to have an appropriate fuse on the 12v line from the power supply of 2 or 3 Amps.

If you had the Raduino plugged in when you powered the board up, that will be the major hit.
The LM7805 does not offer any reverse supply protection, so if the Raduino saw reverse 12v,
that would almost certainly blow the Nano, and probably the display and si5351 as well.
Could have been avoided by having a diode where 12v goes into the LM7805, we can afford to lose a little voltage there.
Try plugging just the Raduino into a host computer (no connection to the uBitx) via the mini-USB connector, see if it comes to life.

If you have a very new board from hfsignals, than the TDA2822 is likely socketed and easy to replace.
Most likely blown if it saw a reversed 12v.

The 78L05 at U2 may have blown.

The remainder of the radio is suspect, but may well have survived.


Jerry


On Wed, May 16, 2018 at 08:36 pm, R. E. Klaus wrote:
If you built it per the plans with the diode across the power jack, you may be lucky and just shorted the diode.? I've replaced hundreds of protect diodes in various mobile equipment with no further issues. If you didn't then it's time to break out the multimeter and start checking for shorted semiconductors and ICs.
Roxie -- K1AUS
Re: uBitx Opto Coupler / VFO not working #ubitx-help #ubitx

 

Thanks!

I send you replies :-)
Re: Core for Output Transformer

 

Only problem is the 002 is 10x the price of the 202....
Re: #ubitx #ubitx-help #ubitx-help #ubitx

R. E. Klaus
 

If you built it per the plans with the diode across the power jack, you may be lucky and just shorted the diode.? I've replaced hundreds of protect diodes in various mobile equipment with no further issues. If you didn't then it's time to break out the multimeter and start checking for shorted semiconductors and ICs.
Roxie -- K1AUS
Re: Core for Output Transformer

 

Bill
do you mean you fitted it for the power feed to the finals instead of the Chokes?

glenn


On Wed, May 16, 2018 at 07:34 pm, K9HZ wrote:

Actually I just tried/ wound a BN61-002 and it seems to be the winner so far.? Doesn¡¯t heat up at full power and is extremely wide banded¡­

?

?

Dr. William J. Schmidt - K9HZ

?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Nick VK4PLN
Sent: Wednesday, May 16, 2018 8:09 PM
To: [email protected]
Subject: Re: [BITX20] Core for Output Transformer

?

THanks GLen.

I was about to suggest using dual bn43-202 for the output and power feeding... should be easy enough to fit in the existing board...

Wonder if it will be better to do this or a bifilar wound 10T FT50-43 for feeding in the power?

73 Nick VK4PLN

?

Virus-free.

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