Re: Letting the smoke out
Trace the track from IRF drain through L8 I am willing to bet L8 is fried
or track burnt.
If your 10A fuse blew then the PCB tracks didn't have a chance!
From the drain to the power pin at PA power 1 should show 0 Ohms. In
your case it wont
and you could friend what has fried. It could even be the 2 pin power
connector wire.
Good luck
Raj, vu2zap
At 17-03-2017, you wrote:
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I received my BITX40 kit and
wired it up on my workbench. The receiver worked well and I made three
QSOs before disassembling it to install in a homemade case. While
reassembling the IRF150 tab shorted to the case? with the power on.
This blew the 10 amp fuse on my 13.7 volt power source and literally
produced smoke from around C157. Fortunately the receiver still functions
but I get no transmit power out. It appears that C157 was not damaged and
it is not shorted. I checked L8 and T7 for continuity and they seemed OK.
I replaced the IRF150.
What I see now:
0.17 A draw on receive, rises to 0.29 A when PTT pushed but goes no
higher
about 9 volts on the drain of the IRF150, drops to 0.0 volts when PTT
pushed, speaking into mike causes slight negative voltage
(-0.15V)
Any suggestions on what (and how) to check next?
??? Thanks
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Re: Changing frequency display
College Professor Simon Thompson
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On Mar 16, 2017, at 1:39 PM, Jack Purdum via Groups.Io < econjack@...> wrote:
Looks good!!
Jack, W8TEE
Jack
Sounds like you will have a maxed out BITX40.
I made the code changes. Seems to work. I only had the Raduino?powered up for the test.
Thanks
Randy, K7AGE
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Re: Letting the smoke out
there's a 5 v regulator-U3 next to Rv1.? Carefully check for output on U3.? Also maybe the Rv1 got fried. If you replace Rv1 put a tick mark where the old one is set or measure for ohms. You need a decent iron re the ground plane is a heat sink. Look at the condition of R150 (47ohm) (at the corner of Rv1 case.
Good luck Larry WA9DOH
My eyes are sore from looking at this SMD Hi.? Need a magnifier/lamp.
On Thu, Mar 16, 2017 at 5:52 PM, KD8CGH <rkayakr@...> wrote: I received my BITX40 kit and wired it up on my workbench. The receiver worked well and I made three QSOs before disassembling it to install in a homemade case. While reassembling the IRF150 tab shorted to the case? with the power on. This blew the 10 amp fuse on my 13.7 volt power source and literally produced smoke from around C157. Fortunately the receiver still functions but I get no transmit power out. It appears that C157 was not damaged and it is not shorted. I checked L8 and T7 for continuity and they seemed OK. I replaced the IRF150. What I see now: 0.17 A draw on receive, rises to 0.29 A when PTT pushed but goes no higher about 9 volts on the drain of the IRF150, drops to 0.0 volts when PTT pushed, speaking into mike causes slight negative voltage (-0.15V) Any suggestions on what (and how) to check next? ??? Thanks
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Re: Letting the smoke out
Hi
In this directory, you will find my table of transistor voltages and schematics highlighted for receive and transmit signal paths.
Hope these help.
Randy, K7AGE
On Thu, Mar 16, 2017 at 3:52 PM, KD8CGH <rkayakr@...> wrote: I received my BITX40 kit and wired it up on my workbench. The receiver worked well and I made three QSOs before disassembling it to install in a homemade case. While reassembling the IRF150 tab shorted to the case? with the power on. This blew the 10 amp fuse on my 13.7 volt power source and literally produced smoke from around C157. Fortunately the receiver still functions but I get no transmit power out. It appears that C157 was not damaged and it is not shorted. I checked L8 and T7 for continuity and they seemed OK. I replaced the IRF150. What I see now: 0.17 A draw on receive, rises to 0.29 A when PTT pushed but goes no higher about 9 volts on the drain of the IRF150, drops to 0.0 volts when PTT pushed, speaking into mike causes slight negative voltage (-0.15V) Any suggestions on what (and how) to check next? ??? Thanks
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Re: Routing power -or- BUGGER, I think I may have fried it
Try disconnecting the rArduino module.? Also I would be Leary to plug the rArduino into my USB port until you can clear that module isn't a short. 12 V. on the main board has a connection to the P.A. and the other to the receiver connection. Maybe disconnect the LCD module and then pull the P.A. power plug. apply 12v and see if something comes up re the main board.
With rArduino module disconnected hook up the power to the main board only and see if anything goes.? Should hear the speaker noise with working volume control.
I'm suspicious of the 12-5v. regulator on the LCD module.? Mine gets extremely hot as I say finger burn hot. ?regulator should shut itself down if it gets hot.? Regulator is 7805SVC ?Data sheet is on line.? Not sure yet if others have a hot regulator.? At min. install a heat sink.
(I've been considering a pico fuse or a 20mm fuse holder/fuse- fusing the power supply lines).
The are also a few regulators on the main board.(see diagram). Check the electrolytic caps for bulges or splits on the tops. Dose your power supply have a current meter? Hope these suggestions help. Larry WA9DOH
On Thu, Mar 16, 2017 at 12:50 PM, richard kappler <richkappler@...> wrote: I'm a RTFM kinda guy, not so much a look at the pictures guy.
I finally got all my parts in, finished assembly this morning. I half expected smoke and flames (said in jest), instead I got nothing. ?
Under Step 4: Wire up the Raduino, it says solder the black wire to the DC power socket and solder the orange wire to the DC power switch on the volume control. I dutifully soldered the black to +12V.
My power supply is a little 2.5 amp rig, adjustable up to 15 volts . It works, I tested it, it is set to supply 12.4 volts to the BX, as read on both the installed ps meter and with my multimeter. When I hook it up to my BX, thankfully, it reads 0. I say thankfully because nothing seems to have happened, no readout from the LCD when I turned the volume pot on, but then again, no smoke, sparks or pops either. I turned it off and started in on the BX with my multimeter and sure enough, I had a hard ground. When measuring resistance between the hot and the 2 grounds on the DC power socket) I get a big fat zero point zero zero.
I went back and re-read the directions, it would seem I did it correctly, then I looked at the 1st picture which clearly shows the black going to ground. BUGGER. I unsoldered it, soldered it to ground on the DC power supply, checked with my multimeter, infinite resistance between +12V and ground. HOORAY!!!
But nothing happens when I power it up. Have I most likely fried it, or have I buggered up some other connection? If I've most likely fried it, I'll go order another. Thankfully in this arena stupidity only costs 59USD and about a month of waiting.
I'm hopeful that it's not fried though, as the meter on the ps, when hooked to the BX, never showed even a hint of voltage out. So... with fingers crossed, what would be the next step in troubleshooting? Can I get a little guidance here?
regards, Richard - W2KAP 
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Re: Letting the smoke out
Here is a link to a message thread about the voltage measurements.
/g/BITX20/topic/bitx40_transistor_voltage/4336465?p=,,,20,0,0,0::Relevance,,Voltage+measurements,20,2,0,4336465
Should point you in the right direction.
Marco - KG5PRT?
On Mar 16, 2017 6:34 PM, "Ion Petroianu" < ion.petroianu@...> wrote: You should see the voltage that the power supply provides at the drain of IRF510 when in receive and very close to that when PTT pressed as there is almost no ohmic resistance in the circuit if everything is good. The current path is power plug, wire, power switch, L6 and T7 winding 1-6 and all the PCB traces in between. I would get the ohmeter and try to find out where are you dropping so much voltage when no current is running through (from 12V to 9V).
--
Ion
VA3NOI
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Re: Letting the smoke out
You should see the voltage that the power supply provides at the drain of IRF510 when in receive and very close to that when PTT pressed as there is almost no ohmic resistance in the circuit if everything is good. The current path is power plug, wire, power switch, L6 and T7 winding 1-6 and all the PCB traces in between. I would get the ohmeter and try to find out where are you dropping so much voltage when no current is running through (from 12V to 9V).
--
Ion
VA3NOI
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I thought I'd start a new thread RE inductance of FT37-43 toroids.? I just measured the inductance of an FT37-43 wound with 10 turns #28 wire.? Measurements at 1, 2, and 7 MHz. using the series resonance method. Inductances measured were 38.5, 35.8, and 20.2 ?H.? This corresponds to calculated Al's of 385, 358, and 202.? The Q is very low for coils wound with these ferrite cores and the dip at 7 MHz was barely discernible.? The lower Al at 7 MHz is consistent with the roll-off of the material permeability starting at about 2.5 MHz or so.? Also if you look at the coil winding data on both Amidon and Kits and Parts sites you will see that the inductance values for a given number of turns is around 20% higher than a calculated value using their published Al numbers.? This all relates only to the type 43 material.? Mike K5ESS
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I received my BITX40 kit and wired it up on my workbench. The receiver worked well and I made three QSOs before disassembling it to install in a homemade case. While reassembling the IRF150 tab shorted to the case? with the power on. This blew the 10 amp fuse on my 13.7 volt power source and literally produced smoke from around C157. Fortunately the receiver still functions but I get no transmit power out. It appears that C157 was not damaged and it is not shorted. I checked L8 and T7 for continuity and they seemed OK. I replaced the IRF150. What I see now: 0.17 A draw on receive, rises to 0.29 A when PTT pushed but goes no higher about 9 volts on the drain of the IRF150, drops to 0.0 volts when PTT pushed, speaking into mike causes slight negative voltage (-0.15V) Any suggestions on what (and how) to check next? ??? Thanks
|
Hi Rafal,
No you have not missed anything and you are not the first to notice the short comings of the design, Allison KB1GMX has also done a very nice analysis of the Bitx design with suggestions as to how it might be improved (of course with some added complexity).
The Bitx is like most things a compromise design (to keep it simple) and yes the single transistor amps and crystal filter have a Zin/Zout of about 200 ohms while the mixers are 50 ohm so there is mismatch and some performance lost.
Also Farham has noted that for better IP3 performance at 40m the first Rx RF amp should probably be disabled but then if you are using your Bitx in the field with a simple wire antenna strung up in a tree the extra gain is probably makes things a little easier.
Yes the Bitx could be better but then it would become more complex, so the trade-off.
Regards,
Peter VK1XP
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Show quoted text
On 17-03-2017 06:41, Rafa? Lichwa?a wrote: I plan to build BITX40 TRX, so I've read the project description and
analyze the circuit. As it is well described on the web page, there
are single transistor amplifier stages which have the following
input-output impedance translation:
Rout = (Rfeedback * Remmiter) / Rinput
In all stages there are Rfeedback = 1.1k (two 2.2k in parallel from
both amplifier directions) and Remmiter = 10R.
That means we have the following impedance translation:
Rout = 11000 / Rin
So now, analyzing the circuit starting from the 50R antenna, we have
the following impedances:
antenna: 50R
LPF-input: 50R
LPF-output: 50R
1st AMP-input: 50R
1st AMP-output: 220R (after translation)
diode MIXER(assuming equal impedances on each port): 220R
2nd AMP-input: 220R
2nd AMP-output: 50R (after translation)
Xtal BPF-input: 50R
Xtal BPF-output: 50R
3rd AMP-input: 50R
3rd AMP-output: 220R (after translation)
AND.....
now there is PI-attenuator (-3.85dB) with both 220R shunt to GND and
22R in series.
That means this attenuator is designed for 50R input/output impedance
- it does NOT match 3rd AMP output impedance which is 220R!
Did I miss something or I've just misunderstood the circuit design?
Best regards,
Rafal SP3GO
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Anyone, its really annoying TX pop, just need to get rid off it.
Phil - G7BZD
On Wed, Mar 15, 2017 at 8:30 PM, philip yates <phil@...> wrote: I know its been discussed, but I am struggling to find a solution to the TX pop. Anyone ???
Taken me a while to get started as I had to start ordering components, so I could actually do some modding, ?couple of nice resistor, capacitor and electrolytic kits now on the shelf,? threw my old collection of parts away when we moved.
Thanks Phil-G7BZD
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Jack,
We really do appreciate your help via this list. I think most of the "when will it be done" questions are expressions of eagerness to see your new radio.
73 de w9ctw
" . . . Meanwhile, I'm trying to contribute on the software end of things even if I can't test it. I thought some help is better than no help."
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Re: Routing power -or- BUGGER, I think I may have fried it
Sadly no. I've been unemployed for over two months (but Raytheon picked me up, so that ends Monday, HOORAH!), so lack of disposable income is what led me down the QRP path in the first place. Mind you, that's ?not a bad thing. I've wanted to get into Ham for decades, just never had the time, unemployment gave me the time and BITX and my local club have helped me to learn SO much. I figure it's all good being as I've only had my license a month and a half.?
I am actually on the coast of the east coast, so if I can get you I'd ?say we're both doing well! Will give her a shot around 6 your time. Somehow I figure I've got a better shot with the locals, for testing purposes though.
Off to do mundane stuph for a bit.
Cheers! Richard - W2KAP
On Mar 16, 2017 5:10 PM, "Jonathan Peakall" < jpeakall@...> wrote:
No problem at all. Do you have another HF rig to look
for a signal with? I find my BITX to be reasonably sensitive. If
you happen to be on the west coast I'm parked at 7.182 at the
moment. Good luck!
>Thanks for the help, I'm off to see how badly I can
bugger the transmit and PTT bits.
>cheers! Richard - W2KAP
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Re: uBITX - A reboot of the old BITX
I ran into problems with Ebay bought cores. I now stick to Diz's supply at KitsandParts. 73 Ken
On Thu, Mar 16, 2017 at 5:09 PM, VK3HN <prt459@...> wrote: Ken, the FT37-43 that gave unexpectedly high inductances were from a bag of 20 with 22uH windings bought on ebay years ago. They might not even be FT37-43s although they are the same physical size. The ones that gave expected results are from Mark at Minikits in Adelaide, and are no doubt from a reputable source. Sarma, I also thought that the actual inductance of each winding in a trifilar transformer in a diode mixer would not be critical and my originals would probably work. But in a project like this I prefer to eliminate as many unknowns as I can. VK3HN.
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Re: Routing power -or- BUGGER, I think I may have fried it
No problem at all. Do you have another HF rig to look
for a signal with? I find my BITX to be reasonably sensitive. If
you happen to be on the west coast I'm parked at 7.182 at the
moment. Good luck!
>Thanks for the help, I'm off to see how badly I can
bugger the transmit and PTT bits.
>cheers! Richard - W2KAP
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Re: uBITX - A reboot of the old BITX
Ken, the FT37-43 that gave unexpectedly high inductances were from a bag of 20 with 22uH windings bought on ebay years ago. They might not even be FT37-43s although they are the same physical size. The ones that gave expected results are from Mark at Minikits in Adelaide, and are no doubt from a reputable source. Sarma, I also thought that the actual inductance of each winding in a trifilar transformer in a diode mixer would not be critical and my originals would probably work. But in a project like this I prefer to eliminate as many unknowns as I can. VK3HN.
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Re: Changing frequency display
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Show quoted text
From: Randy Hall <listk7age@...>
To: [email protected]
Sent: Thursday, March 16, 2017 3:42 PM
Subject: Re: [BITX20] Changing frequency display
Jack
Sounds like you will have a maxed out BITX40.
I made the code changes. Seems to work. I only had the Raduino?powered up for the test.
Thanks
Randy, K7AGE
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Re: Changing frequency display
Jack
Sounds like you will have a maxed out BITX40.
I made the code changes. Seems to work. I only had the Raduino?powered up for the test.
Thanks
Randy, K7AGE
On Thu, Mar 16, 2017 at 11:50 AM, Jack Purdum via Groups.Io <econjack@...> wrote: When you see comment characters ("//") in front of a statement line, that means it's no longer in the program.
Jack, W8TEE
Just a clarification, am I simply adding the lines in yellow, or am I deleting the line that starts with sprintf and replacing that with the lines in yellow?
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I plan to build BITX40 TRX, so I've read the project description and analyze the circuit. As it is well described on the web page, there are single transistor amplifier stages which have the following input-output impedance translation:
Rout = (Rfeedback * Remmiter) / Rinput
In all stages there are Rfeedback = 1.1k (two 2.2k in parallel from both amplifier directions) and Remmiter = 10R.
That means we have the following impedance translation:
Rout = 11000 / Rin
So now, analyzing the circuit starting from the 50R antenna, we have the following impedances:
antenna: 50R
LPF-input: 50R
LPF-output: 50R
1st AMP-input: 50R
1st AMP-output: 220R (after translation)
diode MIXER(assuming equal impedances on each port): 220R
2nd AMP-input: 220R
2nd AMP-output: 50R (after translation)
Xtal BPF-input: 50R
Xtal BPF-output: 50R
3rd AMP-input: 50R
3rd AMP-output: 220R (after translation)
AND.....
now there is PI-attenuator (-3.85dB) with both 220R shunt to GND and 22R in series.
That means this attenuator is designed for 50R input/output impedance - it does NOT match 3rd AMP output impedance which is 220R!
Did I miss something or I've just misunderstood the circuit design?
Best regards,
Rafal SP3GO
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Re: uBITX - A reboot of the old BITX
Diz's cores come from the manufacturer.
73 Ken
On Thu, Mar 16, 2017 at 3:28 PM, K5ESS <k5ess.nothdurft@...> wrote: .? Not sure who the manufacturer is for these parts.? The cores in question were type 61 material.? I intend to make measurements on the other core types I have.? I¡¯ll post the results. Mike K5ESS ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Ken
Sent: Thursday, March 16, 2017 12:21 PM
To: [email protected]
Subject: Re: [BITX20] uBITX - A reboot of the old BITX ? Where were the toroids bought frm? ? On Thu, Mar 16, 2017 at 1:18 PM, K5ESS <k5ess.nothdurft@...> wrote: Despite some toroid specs that claim Al values to be within 5 to 25% I¡¯ve found some to be as much as 50% off.? Mike K5ESS ? From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Thursday, March 16, 2017 2:01 AM
To: [email protected]
Subject: Re: [BITX20] uBITX - A reboot of the old BITX ? something is dodgy there. the T30-6 that i use invariably needs more turns to get the exact inductance that predicted by the data. i don't know ever is going on. ? On Thu, Mar 16, 2017 at 6:07 AM, VK3HN <prt459@...> wrote: >Calculator shows it should be 22.4 uH.? I agree, Toroids.info doesn't lie!? So is there some inductance amplifying affect from the other two parallel windings?? Can anyone else with a spare 8:8:8 transformer lying around do a reading? ? ? ?
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Raj vu2zap
Ion Petroianu, VA3NOI
Bob Benedict, KD8CGH
Craig Wadsworth
VK3HN
