My curiosity overcame me. ?Pulled the LM7805 from my Raduino (so I was sure I was working with the same manufacturer that hfsigs uses) and verified proper operation with 12v in, saw 5v out. ?Reversed the 12v leads into the LM7805, put on the safety goggles, and powered up. ?Was powering from a 2.5 amp 12v supply. ? The reversed LM7805 was sucking enough current to pull down my 12v switcher to -5v going into the LM7805, saw -2v going out of the LM805. ?Could well be more than -2v going out if I had used a beefier 12v supply. ?Regardless, -2v is sufficient to damage some parts behind the LM7805. ?After a few seconds the LM7805 got hot enough to vent and stink up the room.
So, the LM78** parts offer little to no protection from reversed power supply leads. ?Not surprising, they were designed 40 years ago when such niceties would have been too expensive to include. ?A reversed power supply to the rig could easily blow the Nano on the Raduino. ?The Nano has an internal 3.3v regulator that may or may not save the Si5351, but no guarantees. ?The LM78L09 powering the analog VFO and LM78L05 for the IRF510 bias likely have the same issue.
The LM2940* family of regulators does offer reverse polarity protection and has a lower dropout voltage. ?However it is twice as expensive ($1.00 vs $0.50 from mouser for 10), they recommend at least 22uf on the LM2940* output to maintain stability. ? As mentioned previously, having an LM2940-12 at the main Bitx40 supply going into the board would protect us from reversed power leads, and also avoid trouble from supplies that exceed 12v such as a stack of 4 lithium batteries. ?The IRF510 should be powered separately, as we may want considerably higher voltages and currents there and the IRF510 is plenty cheap.
I am left very curious if Matt's Raduino is still functional. ? Does the display come up if you apply 12v to it?
Jerry, KE7ER
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On Fri, Jun 9, 2017 at 08:27 pm, Jerry Gaffke wrote:
If the LM7805 and LM78L09 regulators avoid passing negative supplies somehow,
might not be just too much damage from reversed power.
But I don't see anything in the LM78** datasheet suggesting that is the case.
Would be interesting to see what they do.
?
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someone just deleted the entire BITX operators map - almost fixed
Someone just deleted the entire layer from the map with all of the information.? This is the problem with trying to keep this open for editing for everyone.? Fortunately I saved the kmz file last night at 9:52pm central and can rebuild the map from there.? If you did anything after that you will need to add your information again.? I have said many times if you need help, just ask.? Reply to one of my messages or email me at KD9CYF At gmail DOT com? .? I am concerned keeping this open puts our data at risk of deletion again.? I am trying to keep this public and not owned by me or anyone else but if this happens again I may have to lock it down to protect it and have operators email me or a group of editors to be added.? I am very open to other suggestions.
the link is the same.? here it is again...
https://drive.google.com/open?id=1Oa_egVdStSJBF5C7mpS6MXrkces&usp=sharing
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Re: add yourself to the new BITX operators map
Did you try using the Chrome browser? I couldn't enter my location using Firefox.
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Re: W8TEE Parts List for TFT/VFO
Mike Nothdurft (k5ess.nothdurft@...) has done a very small PCB that is an adapter for the Type I to Type II board. It plugs directly into my PCB. I just got mine yesterday, so haven't tried it yet, but should be able to test it today. There is a trace that has to be cut, but he can point you to the directions for that...pretty simple. I think he charges $2 (or less) which is cheaper than the Type II board difference in price.
Jack, W8TEE
From: Adrian <a.futrill@...>
To: [email protected]
Sent: Sunday, June 11, 2017 9:39 AM
Subject: Re: [BITX20] W8TEE Parts List for TFT/VFO
Found most of the parts to put this together but been unable to find a supplier of the?AD9850 Type II DDS module companies that advertise them are out of stock and don't know if/when they will be back in stock
Adrian VK4KL
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Re: TFT/VFO Code and PCB Update
What display are you using? At line 1334 in setup() the display ID is read. Print out that value to see if it matches any of the known values in the code. Is it an mcufriend display?
Jack, W8TEE
From: Adrian <a.futrill@...>
To: [email protected]
Sent: Sunday, June 11, 2017 7:23 AM
Subject: Re: [BITX20] TFT/VFO Code and PCB Update
What have I done wrong? Adrian VK4KL 
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Re: W8TEE Parts List for TFT/VFO
Found most of the parts to put this together but been unable to find a supplier of the?AD9850 Type II DDS module companies that advertise them are out of stock and don't know if/when they will be back in stock
Adrian VK4KL
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Re: Raduino V1.01 vs V1.14 Birdie at 7.200
all version is now tested !
and V1.01 to V.05 have lower noise and let signal on the 7.200 Birdie !
can it have something to do with the new display command ?
all are compiled with S5153 V2.01
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Re: add yourself to the new BITX operators map
hi
i am having trouble adding my address- the search bar only comes up with the name of the map
terry gm4dso
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Re: add yourself to the new BITX operators map
hi
i cannot a dd my name etc - the search bar only comes up with the name of the map
terry gm4dso
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Re: TFT/VFO Code and PCB Update
What have I done wrong? Adrian VK4KL 
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Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere
Reminder, 7 pm Sunday night
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Re: add yourself to the new BITX operators map
Just added my QTH.
73,
Shlomo 4X4LF
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Re: Keeps getting better Bitx40
Did that also, and they had the red spot on one.
Leds fitted to S meter now, so it matches the Raduino display.
Phil - G7BZD
On Sun, Jun 11, 2017 at 7:12 AM, Raj vu2zap <rajendrakumargg@...> wrote: That reminded me of scraping off the black paint from OC transistors and making phototransistors.
Cheers
Raj
At 11-06-2017, you wrote:
>BC548 diagram?
>Sometimes its the simple things that trip us up, Used to spend hours with OC71 & OC81 transistors, but that was years ago.... Cough cough..... 40+ years ago, mind forgets things.
>
>Phil - G7BZD
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Re: W8TEE TFT /VFO BOARD Features?
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On Jun 10, 2017, at 8:38 PM, Jack Purdum via Groups.Io < econjack@...> wrote:
The manual is not done yet and more will be added as Dennis and I finish the board(s). Attached is a? picture of the top of my case. The 3 NO pushbottom switches on the top of the case correspond (left to? right) to the SW? fields on the display. In picture number 2 you can see field SW 1 has a 1 display in it.? This means that switch 1(i.e., SW1) is tied to the 1st message in the message queque. The 1st message is displayed at the bottom of the display (i.e., "CQ CQ CQ DE W8TEE"). So if you pressed the left-most push button on the top of the case, the message "CQ CQ CQ DE W8TEE" would be sent in Morse code. Likewise SW2 is tied to message 2 and SW3 is tied to message 3. You can scroll through the fields to review/change the message number. There is enough room for 50 different messages.?
Right now, we have not added code for digital modes. However, right now, I am only using less than 38K of 256K of flash memory (15%) and 1912 bytes (23%) of the 8K SRAM memory, so there is plenty of room to add features. Allard's code should be modifiable for the USB/LSB needs.
We're using the AD9850 chip and are currently not doing anything with the other outputs.
The CW mode will have tune capability, but unlike some other approaches, we produce the CW mode on a secondary board along with AGC and speech compression.
Jack, W8TEE
Jack,
Thanks for the latest releases....? I have been going over the new manual ?and have the board nearly all done.. Just waiting for some chokes and some 78L08.. ? I have a few questions: ? 1. In the manual, on the display there is sw1 sw2 sw3 ? what is that? ? 2.How do I select USB /LSB? I use the digital modes such as jt 65 ? 3. Is there a vfo option - more ?than one vfo? vfoA / vfoB etc or freq storeage so one can jump to saved locations.? ? 4. When putting the bitx in tx is there tune option ?(a carrier for the tuner tuneup)?
? Joe VE1BWV
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Matt,
Here are possible blown parts since they dont have protection:
Complete BFO & VFO, Q7, 8, 9, 10, 11
Mic amp Q12
If the PA was also connected to the same power then IRF510 final.
Check the Base - emmitter voltage of all transistors from Q7 - Q12
Before testing remove the VFO - Raduino signal from DDS1 jack
Short X5 to disable the oscillator
You will get wrong reading if these stages have RF running.
Good luck
Raj
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At 11-06-2017, you wrote: Ok, I feel like an idiot now...
Based on the picture (I don't have the board with me now) it's actually D7 that has blown, not D6.
Apologies for wasting your time!
Matt 2E1HNK
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Re: Keeps getting better Bitx40
That reminded me of scraping off the black paint from OC transistors and making phototransistors.
Cheers
Raj
toggle quoted message
Show quoted text
At 11-06-2017, you wrote: BC548 diagram?
Sometimes its the simple things that trip us up, Used to spend hours with OC71 & OC81 transistors, but that was years ago.... Cough cough..... 40+ years ago, mind forgets things.
Phil - G7BZD
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Re: Amp readings on Bitx40
Sorry Jerry, It was John Bakko
"The board as received should measure ~35 ma. without the PA connected. Preferably, use a separate
power supply for the PA, but the main PS can be used if it is stiff and heavy enough. Then set RV1 to 1-2v.
Connect the PA. Slowly increase RV1 until the total draw for the board and PA is ~135 ma. There should be
~4v on the gate of the IRF510. This may vary quite a bit, but 5v is probably too much."
My mistake on the quote, but if I'm not mistaken, RV1 should be adjusted 100 ma above idle(~250) and then 136 pushes it up to about 1.5 amp when speaking.
Andy
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Where can I get the manual from please Jack
On 11 Jun. 2017 1:45 pm, "Jack Purdum via Groups.Io" <econjack= [email protected]> wrote: There are pictures in the manual and the board is about 3.875"x2.5"
Jack, W8TEE
From: Trent Trent <vk7hrs@...>
To: [email protected]
Sent: Saturday, June 10, 2017 11:06 PM
Subject: Re: [BITX20] W8TEE Pricing for Foreign Orders
Do you have any pics of the boards and sizr by any chance
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There are pictures in the manual and the board is about 3.875"x2.5"
Jack, W8TEE
From: Trent Trent <vk7hrs@...>
To: [email protected]
Sent: Saturday, June 10, 2017 11:06 PM
Subject: Re: [BITX20] W8TEE Pricing for Foreign Orders
Do you have any pics of the boards and sizr by any chance
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Raj vu2zap