Date   
CB amplifiers RM-Italy KL203P

iz oos
 

There are some reasonably priced CB amplifiers on the market that maybe could be hacked for HF use, provided you add lowpass filters and make other mods. One of this is the RM-Italy KL-203P that is meant for SSB with an input power less than 20w and should work as is from 18 to 30Mhz (if you add the low pass filters). This amp also has a switchable receiving amplifier and totally RF sensed (no need for PTT). I know that these should not be over driven and do not represent the best example of linearity but has someone tried one of these?

Re: 2.5 MHz low pass fiilter uses no toroids, SMDs #ubitx

Peter Parker
 

Thanks Glenn!  I do wonder whether 680pF would have been better than the 820pF I used - might shift it up a little which might be desirable for those near a powerful station around 1.5 MHz (in VK most of the really powerful AM stations are ABC below about 900 kHz). 

Re: Net Neutrality Ending

Terry Morris
 

Back in the day, before the Internet, before hard disk drives (we used floppy drives then), and before GUI I began networking with a 110-baud dial up modem. Then when the Internet was beginning I used dial up with a 300 baud acoustic modem and was permitted a connect time of 30-minutes. My mind is sketchy but I think my total monthly connect time was 6 hours. Back then, browsing was something you did with a magazine or book. Don't know what those are? Check wikipedia, hi. -- Terry KB8AMZ​

Re: KD8CEC Firmware S-Meter usage

Don, ND6T
 

Mark,

Ian's circuit is not DC blocked at the output of the LM386 so it will not be zero volts when there is no signal. The simple diode circuit is found here. If you use my AGC circuit attach the lead to the cathode of D2 which is J1 ( NOT J2 , Ralph ) on K5BCQ's kit. Even if you don't want AGC, the kit will provide a nice S meter amplifier and detector by simply connecting +5 volts, ground, and audio input. Then attach your wire from J1 to the S meter input lead. 73, Don

Re: 2.5 MHz low pass fiilter uses no toroids, SMDs #ubitx

Glenn
 


Hi Peter
Yes I guess that might be a bit better although I haven't listened much on my rig so far to know how bad the BC is here. I am in Narre Warren Sth. I think the nearest BC station Tx is at Mulgrave, not even sure which one it is frequency wise.
I will see if i can do a plot though, asap.

glenn


On Mon, Jun 11, 2018 at 01:07 am, Peter Parker wrote:
Thanks Glenn!  I do wonder whether 680pF would have been better than the 820pF I used - might shift it up a little which might be desirable for those near a powerful station around 1.5 MHz (in VK most of the really powerful AM stations are ABC below about 900 kHz). 

Re: 2.5 MHz low pass fiilter uses no toroids, SMDs #ubitx

Peter Parker
 

Mulgrave is 3MP on 1377 kHz. So it would be a good test of the filter. 

Was listening with it tonight and all was good.  Could hear interstate stations on 1548 but not local stations below about 900 kHz.  160m amateur reception would probably be down but OK. 

If you wanted better rejection you could just use VK3IL's capacitor values plus RF chokes for 1.5 uH.   

Re: Messed up removal of TDA2822

Sajid Rahum
 

Thank you both Raj and Sharma.

Did it both ways - cut at tips closer to the chip. But either the solder iron is not too hot - I kept it around 200c.  Anyway, i then did the old fashioned way by wiring up the 8 pin socket.

My main question is if you look at the mainboard bottom side - the solder fell off (top left pin); not sure where it was connecting to so that if i need to wire it where to take it to?

Re: Messed up removal of TDA2822

Michael Maiorana
 

Hello.
It doesn't look like that pad went anywhere on the bottom of the board. If you soldered your 8 pin socket to the top pads, it is likely going to work fine.
Give it a try and see if it works.
Mike M.
KU4QO

On Mon, Jun 11, 2018 at 7:15 AM, Sajid Rahum via Groups.Io <zs735@...> wrote:
Thank you both Raj and Sharma.

Did it both ways - cut at tips closer to the chip. But either the solder iron is not too hot - I kept it around 200c.  Anyway, i then did the old fashioned way by wiring up the 8 pin socket.

My main question is if you look at the mainboard bottom side - the solder fell off (top left pin); not sure where it was connecting to so that if i need to wire it where to take it to?


uBitx V4 pic

 

Attached is a V4 pic for anyone who is curious!

Cheers

--
Raj, vu2zap
Bengaluru, South India.

Re: Messed up removal of TDA2822

Sajid Rahum
 

Much appreciated Mike.

Will be putting the entire box together this week.  Going to use Baofeng mic as well.

Re: Messed up removal of TDA2822

 

Pin 8 at the bottom is not connect anywhere there. Its connected to a capacitor C75 on the top plane.
Check there.

Use a little higher temp. and clean up the board. As I said mount the socket on the board neatly!

At 11-06-18, you wrote:
Thank you both Raj and Sharma.

Did it both ways - cut at tips closer to the chip. But either the solder iron is not too hot - I kept it around 200c. Anyway, i then did the old fashioned way by wiring up the 8 pin socket.

My main question is if you look at the mainboard bottom side - the solder fell off (top left pin); not sure where it was connecting to so that if i need to wire it where to take it to?

Re: Messed up removal of TDA2822

Marc Jones
 

One of the easiest ways to remove a blown IC , If your not to confident in soldering , Take s sharp pair of side cutters, Cut each leg of the IC close to the IC main body , Remove the actual IC , Your now left with the 8 solder pins still soldered into the PCB, With s pair of long nose pliers or tweezers,  heat up the solder with your iron, And gently  pull each pin out from the board, once this has been done a good solder sucker will remove the rest of the solder leaving clean holes ... Soldering is a skill, Practice makes perfect ... Once your competent and you've gained  the skill you can  remove the IC with solder sucker alone ..

Practice on scrap PCBs first though , This saves the damage as you have here on your radios PCB.

Regards

Gw0wvl


On Mon, 11 Jun 2018 at 1:41, Sajid Rahum via Groups.Io
<zs735@...> wrote:
All:
Need help. I cut the TDA2822 (WX model) and tried my best to get the pins out - used copper wick etc. no luck.  

Landed up wiring the 8 pin dil with replacement NJM chip.  When i turned around, looks like one anchor dropped out - you can see the flux showing. 

My worry where did that bit that dropped out was to go to?  I will place a wire if needed.

This was been a nightmare replacing the 2822.

Any suggestion is welcome

Re: Net Neutrality Ending

Bo Barry <wn4ghv@...>
 

Agreed. Sorry

No Power

G8HAV
 

Hi,
Having built  the uBITZ and been checking receive and all is well. Loaded KD8CEC version 1.8 and checked receive again.

Now tried CW TX but got no power out. Read all the topics on a previous 'No Power' topic and followed all the checks.
All TX voltages are present and the main oscillators must all be running as receive is working well.

Got a simple 10 MHz scope and checked the output from the MIC amp and CW tone to the mixer and I cannot detect any change of signal 
when operating the PTT and the CW key. 

I will wire up a MIC element and test the audio from that later.

Any ideas would be welcome as I am reasonably competent in fault finding; I may make a tone generator and inject a tone into the mixer to check for power out.
There is a CW  tone output on pin 15 which I think is where the Raduino is plugged into the motherboard. 

That's my next check.

Thanks

Re: No Power

ajparent1/KB1GMX
 

CW-Tone is user side tone and does not modulate the transmitter.

CW-Key and a change of frequency to the Si5351 does CW transmit.
This is fairly unique and provides a clean CW transmit.

So for CW tranmit you must see CW-key change state and the output of clk2
must be at the CW transmit frequency.  ( I believe also inside a ham bad).

Allison

Re: UBITX Touch Control TFT Display

Bo Barry <wn4ghv@...>
 

I built one but doesn't look as nice yet. On the bench for testing.
Thanks tips. I only have one buck converter for the mega
Going to 'scope out all lines soon.
Is the cap.22uF or 0,44uF?  🤔
Bo W4GHV 

Re: No Power

Ian Lee
 

G8HAV

What changes do you see on the LCD when you press the CW Key?
Can side tone be heard through the speaker?

Ian Kd8CEC

2018-06-11 22:27 GMT+09:00 G8HAV <g8hav@...>:

Hi,
Having built  the uBITZ and been checking receive and all is well. Loaded KD8CEC version 1.8 and checked receive again.

Now tried CW TX but got no power out. Read all the topics on a previous 'No Power' topic and followed all the checks.
All TX voltages are present and the main oscillators must all be running as receive is working well.

Got a simple 10 MHz scope and checked the output from the MIC amp and CW tone to the mixer and I cannot detect any change of signal 
when operating the PTT and the CW key. 

I will wire up a MIC element and test the audio from that later.

Any ideas would be welcome as I am reasonably competent in fault finding; I may make a tone generator and inject a tone into the mixer to check for power out.
There is a CW  tone output on pin 15 which I think is where the Raduino is plugged into the motherboard. 

That's my next check.

Thanks



--
Best 73
KD8CEC / Ph.D ian lee
kd8cec@...
www.hamskey.com (my blog)

Re: UBITX Touch Control TFT Display

Bo Barry <wn4ghv@...>
 

One more comment
Anyone found a good cutout panel for the 2.8 display? I'm terrible with a hacksaw.  Bo W4GHV 

Re: CB amplifiers RM-Italy KL203P

Richie Chambless
 

I’ve thought about these amplifiers, also. Despite the negativity around them, I think the only thing that’s missing is the low pass filters (the ones biased for linear operation). I’m thinking they all use RF transistors, but I could be wrong.

Re: Transmitter Mods

Ralph Mowery
 


As mentioned you do need a good stereo microscope.  I use one of the better low end ones by Amscope se4000z for just under $ 200.  It comes with 10 and 20 power lenses.  I most often use the 10 power.  That and a very fine soldering iron and some .015 or so solder. You can get one of the hot air rework stations from ebay for about $ 60 that has a fine tipped iron and hot air wand.  Doubt they would hold up under heavy usage,but for a hobby they are fine.  At 68 I am lucky not to have shaking hands either..  My problem is picking up the parts with the tweezers and then taking off my glasses to look through the microscope.

Ralph KU4PT


On Mon, Jun 11, 2018 at 12:35 AM, Tom Christian <tmchristian@...> wrote:
Hahaha!  I'm amazed that anyone can work with 0201! Some day maybe in my dreams.....:). Thanks again!
Tom
AB7WT
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