Date   
Re: Trustworthy 2N2222A?

Doug W
 

On Fri, Jan 31, 2020 at 02:10 PM, Rob French (KC4UPR) wrote:
I'm looking to get some 2N2222A
Have you looked at Tayda?

https://www.taydaelectronics.com/pn2222a-pn2222-transistor-npn-40-volts-1a.html
https://www.taydaelectronics.com/t-transistors/2n-series/2n2222a-2n2222-npn-transistor-0-8a-40v-to-18.html
 
--
www.bitxmap.com

Re: Overvoltage spike killed my V4

Evan Hand
 

John,

I would start as Adrian has suggested and try to power up the board without the connection to the power amp (the brown wire on the three wire power connector).  If the fuse does not blow, then you know that at least one of the finals is blown (the other parts of the transmitter power circuits would not be powered until the rig is put into transmit mode.

If the over current continues with the Power Amp (PA) power feed removed, then there is something shorting on the receive side, as power is not applied until the TX/RX relay is energized.  I would suspect the audio sections of the rig before the bidi amps.  If you check with the schematic, you will see resistors between the 12 volt RX source and the preamp (Q70 - R52) and the final audio amp (Q71,72,and 73 - R71).  Remove one of these at a time to try to isolate which section is shorted.

Above are just suggestions.  The very first thing to do is to verify all wiring and any external components.
73
Evan
AC9TU

Re: Trustworthy 2N2222A?

 

Hmmm,

Well these are the CW power measurements for my ver3: 

2019.02.10
Power measurements on as-delivered uBITX.
Supply: 13.8VDC, Current: 0.17A on RX
 
Band Freq, kHz Vrms A W
75/80 3500 22.9 1.81 10.5
75/80 3750 25.1 2.04 12.6
75/80 4000 26.9 2.4 14.5
40 7000* - - -
40 7001 20.4 1.69 8.3
40 7150 20.6 1.76 8.5
40 7300 20.9 1.82 8.7
30 10100 15.1 1.3 4.6
30 10150 14.8 1.28 4.4
20 14000 16.6 1.63 5.5
20 14175 16.5 1.66 5.4
20 14350 16.4 1.68 5.4
15 21000 7.54 1.06 1.1
15 21225 9.7 1.06 1.9
15 21450 9.62 1.07 1.9
10 28000 7.5 1.05 1.1
10 28850 7 0.88 1.0
10 29700 5.8 0.81 0.7


I haven't done any mods, but the rig certainly could use some help where ever it could be found I think.  Anyway, I don't think $10 or so is too much to spend for some improvement.  How much in total have some here spent on their bitx projects?  I'm sure some have spent many hundreds of dollars judging by the number of ubitx's and accessory kits purchased...

73,


Mark.

Re: Trustworthy 2N2222A?

Rob French (KC4UPR)
 

Hey Curt,

I've got a V5.

Which device(s) in the Tx amplifier chain were you referring to?  I have not replaced any amps at all, this is my first "on-board" mod to the uBITX (I have previously installed the kit-projects AGC and BCI filter).  I see in the V5 bidi amplifiers there are BFR93W's, versus 2N3904 in the V4, so I'm guessing maybe the last thing you were referring to is moot.

In truth, I haven't actually measured my V5 output yet (waiting on my watt/SWR/antenna tuner) so I probably shouldn't go changing anything quite yet regardless.  But I definitely want to make sure I'm getting good power out at least down thru 20 meters--I'm using an attic antenna, would like to get whatever oomf out of the radio I can!

Rob KC4UPR

Re: : #V6 software issues help please #v6

Evan Hand
 

WB0WQS,

The most likely adjustment for the "bassy" is the BFO.  The electret mic would not normally be bassy.

73
Evan
AC9TU

Re: Ubitx V^ just assembled, VFO Doesnt Work, no receive/audio

Evan Hand
 

After you verity that the TX/RX issues is resolved, I would connect a pair of wires to the Tip and Sleeve, or Ring and Sleeve (both are connected to the output of the audio amp on the main board.  Unplug the speaker from the main board, and connect the wire from the temporary plug to the the wires of the speaker.  If the audio is there, then the speaker is OK.  If not, then look at the wire/speaker to verify that there is not a broken connection.

At this point the we know that the audio sections of the main board are working (you have audio in the headphones).  We just need to know where we are losing the audio in the link to the speakers.

BTW. you are removing the headphones when testing  the speaker?

73
Evan
AC9TU 

Re: Overvoltage spike killed my V4

Adrian Chadd
 

Hi!

Disconnect the power rail going to the finals transistors and see if
the rest of the bitx4 powers up and receives. It's possible one of the
finals transistors is a dead short after that.



-adrian
(kk6vqk)

On Fri, 31 Jan 2020 at 10:15, John Faivre <@WA9SGD> wrote:

My power supply regulator failed. The crowbar circuit kicked in at 15v and blew the fast blow fuse, but my board is dead. The voltage could have gotten as high as 27v before the fuse blew.

The 2 amp fuse blows as soon as it is powered on. I don’t see low resistance on either the main or final power circuits. I’ve meter checked all the transistors, diodes, an caps.

I have disconnected everything from the main board and it still blows. The Raduino still works if powered from the USB port.

Anyone have an idea how I might trouble shoot this?

I May be in the market for a V4 or V5 board, if anyone had one to sell.

--
John Faivre WA9SGD

Re: Trustworthy 2N2222A?

Curt
 

$2 each yikes!  for what improvement?  if you really want them, ask around your local ham club or visit a hamfest (or in the UK they call them Rallys I am told). 

kitsandparts.com (W8DIZ) is a reputable source - but don't see what you are looking for there now.  [and a few folk may be killing off some of the population preparing for FDIM no-smoke competition again]

Isn't the power roll-off in the uBITX a feature - since we tend to need more power at lower frequencies?  okay a healthy 10 watts at 28 MHz may be appreciated - but perhaps better solution is a new rig, if you really want that.  (maybe your track record of uBITX mods is much better than mine - so you need something new to do?  my last bug-a-boo was learning that a relay can go astray - while taking a little while to figure out it was the cause]

I don't know those little SMT 3904's look kind of cute!  have you already replaced the 45 MHz Tx amplifier devices with those high Ft critters?  seems like a more useful effort to me for a v3-v4. 

73 Curt

Re: V6s

Jim
 

Package pics -- I had already taken the radio out.  Let me know if you need more -- it was well packed.

Re: Trustworthy 2N2222A?

Rob French (KC4UPR)
 

Doh, looks like the 2N5109s are out of stock.

Which 2N2222's were you referring to?  

Re: Trustworthy 2N2222A?

Rob French (KC4UPR)
 

Hey Ted,  I'll check the link out... I guess I was skeptical right off the bat for anything from eBay.  I'll take your recommendation ;-).

As I mentioned in the other post, for the resistor I think I will just try to use the unused resistor in each pair as the additional resistor, i.e. since each pair of 2N3904's gets replaced by a single 2N5109.  

If I don't burn one up, I'll use the spare to make that wideband RF preamp you mentioned; looking at the kit from kitsandparts.com, I think I've got everything on hand except the transistor, so might as well just wire it up dead-bug style.

And you didn't change Q90, correct? Left it as a 2N3904, not a BFR106.

Re: Trustworthy 2N2222A?

Ted
 

.....but if you really want 2N2222's, these seemed OK when I bought some a while back -

Re: Overvoltage spike killed my V4

Clark Martin
 

If you have a variable voltage supply use that while monitoring the current to slowly increase the supply voltage until the current gets up to around 200 mA. Then start probing see where the current is going.

Clark Martin
KK6ISP

On Jan 31, 2020, at 10:15 AM, John Faivre <wa9sgd@...> wrote:

My power supply regulator failed. The crowbar circuit kicked in at 15v and blew the fast blow fuse, but my board is dead. The voltage could have gotten as high as 27v before the fuse blew.

The 2 amp fuse blows as soon as it is powered on. I don’t see low resistance on either the main or final power circuits. I’ve meter checked all the transistors, diodes, an caps.

I have disconnected everything from the main board and it still blows. The Raduino still works if powered from the USB port.

Anyone have an idea how I might trouble shoot this?

I May be in the market for a V4 or V5 board, if anyone had one to sell.


Re: Trustworthy 2N2222A?

Ted
 

Rather than swap the 6 predriver and drivers with them, go for three of these & a spare - https://www.ebay.com/itm/401310061467.  Better output, especially upstairs on 20 meters and up. You only need one 2N5109 for each position that would have taken two 2N2222's. 

Of course you'll still need to add a parallel 20-ohm resistor to each emitter bias resistor to see the full benefit.


- Ted
   K3RTA

Re: Trustworthy 2N2222A?

Ken
 

Hi Rob

If they come from China, don't bother. I went this same thing last spring and they were all duds. You're better off getting them from a reliable source.

73

Ken VA3ABN

On Fri, Jan 31, 2020 at 3:10 PM Rob French (KC4UPR) <robert@...> wrote:
Hey guys,  I'm looking to get some 2N2222A transistors for my uBITX mods.  Does the following appear a trustworthy source?

2N2222A - Bipolar (BJT) Single Transistor, NPN, 40 V, 300 MHz, 1.2 W, 800 mA, 100 hFE (Pack of 50) (2N2222A) https://www.amazon.com/dp/B07QK2QR8P/ref=cm_sw_r_cp_apa_i_yGinEb6V8FVW4

Otherwise,  I was planning on the $2 each ones from Central at Mouser. 

Trustworthy 2N2222A?

Rob French (KC4UPR)
 

Hey guys,  I'm looking to get some 2N2222A transistors for my uBITX mods.  Does the following appear a trustworthy source?

2N2222A - Bipolar (BJT) Single Transistor, NPN, 40 V, 300 MHz, 1.2 W, 800 mA, 100 hFE (Pack of 50) (2N2222A) https://www.amazon.com/dp/B07QK2QR8P/ref=cm_sw_r_cp_apa_i_yGinEb6V8FVW4

Otherwise,  I was planning on the $2 each ones from Central at Mouser. 

Re: Made Mods to V3 uBitx - no longer transmitting #ubitx-help #v3

Michael Shreeve
 

And, also, if I were to build the same rf probe you decide to build, then, since I have an un-modified rv3 I can measure some of these rf voltages. We could compare what we see.

Re: Ubitx V^ just assembled, VFO Doesnt Work, no receive/audio

stefan@...
 

Hey Evan, yes I am using the mic that was included in the kit, and will definitely try a blank 3.5mm plug to see if the mic is the issue. To test the speaker, you're saying to take a 3.5mm male to male and plug one end in the headphone jack and then touch the tip(or is it ring? Not sure how it's wired) to one of the speaker posts and see if i hear audio. If I do, I have a bigger problem somewhere on the board, otherwise if I dont it is either the speaker or the ground to the speaker? Or if I cut one end off of a male to male and hooked it directly up to the speaker, it would tell me definitely that it is the speaker. I will try tonight when I get home. I think I have a good shot at getting on the air tonight thanks to everyone on this thread. I will make sure to have a dummy load on it. The other times it transmitted I had an antenna hooked up to it that showed resonant(on my NanoVNA) on the frequency I had it set to, but I will play it safe with the dummy load. Out of curiosity, how long would transmitting with no antenna(or badly tuned antenna) take to damage the radio? Instantly? A Couple seconds?

Re: Overvoltage spike killed my V4

John Faivre
 

Thanks I’ll try that
--
John Faivre WA9SGD

Re: Overvoltage spike killed my V4

Gordon Gibby
 

One time I picked up an extraordinarily expensive, custom piece of very very complicated technology for an alphabet agency located near Washington, and requiring top secret security clearance to work there.   I was a college intern working on my first degree in electrical engineering. 

Plugged the new device in, turned it on and there was a sound similar to popcorn popping, which lasted only about five seconds. 

Opened it up, and there were a little black plastic tops of integrated circuits scattered everywhere— almost everyone of them had completely blown up, exploded!!!!    I could see my salary for the next 10 years going down the drain.....  my knees were weak.  

Took a look at how they had wired the AC powerline input, and discovered a physical short to the +5 volt line..... When you pay five or six figures for a piece of equipment, you would think that they could build it better than that, no?




On Jan 31, 2020, at 13:23, Gordon Gibby via Groups.Io <docvacuumtubes@...> wrote:

Haul out your voltmeter, and start measuring the voltage across the emitter resistor of every stage active in receive, and then every stage active in transmit.

Then use Ohms law to calculate the current through each transistor (I=V/R)

Somewhere way back there, it has been published here for many of the stages, but in general it should be a few milliamps on each stage.  If it is zero when the stage should be conducting, that gives you a clue that the transistor may be open.   If the current is high, then measure the collector voltage and see if the stage is completely saturated.  (collector voltage very close to emitter  voltage). That might be a shorted or damaged transistor. 

Can’t remember if those versions have integrated circuit audio amp, however poking around with a crystal earphone would let you hear the signal at earlier stages

Gathering information is the first part of diagnosis.    And while you’re at it, measure and see if the 5 V regulator still regulates.  

Some of the relay control transistors may have gotten fried also. 

Once you get started, you’ll get a lot better at this quickly

Not the end of the world usually.   

On Jan 31, 2020, at 13:15, John Faivre <wa9sgd@...> wrote:



My power supply regulator failed. The crowbar circuit kicked in at 15v and blew the fast blow fuse, but my board is dead. The voltage could have gotten as high as 27v before the fuse blew.

The 2 amp fuse blows as soon as it is powered on. I don’t see low resistance on either the main or final power circuits. I’ve meter checked all the transistors, diodes, an caps.

I have disconnected everything from the main board and it still blows. The Raduino still works if powered from the USB port.

Anyone have an idea how I might trouble shoot this?

I May be in the market for a V4 or V5 board, if anyone had one to sell.

--
John Faivre WA9SGD