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Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

After weeks of trying I finally had some success! First QSO with Rick WB0NPM then Don ND6T. I also hear a few others but can't make them out. Rick mentioned an early net 8AM on 7186, may give that a try.
Re: Usb sound card.

 

I had one that looked similar to your Ebay post and it didn't have any isolation between the computer ground and the audio in and out ground. I did the VOX interface as well. I intend my Bitx to be mostly portable so I skipped the transformers in this one to save space and just added a resister and some caps to get some DC isolation. We will see if that was a mistake but it seems to be working fine as of now.
Re: Usb sound card.

 

¿ªÔÆÌåÓý

I have worked with a lot of cheapy ones from aliexpress they wont have any isolation. I use a vox interface just for that. It does add more cables to the mess but it works.

Gl
73
David
N8DAH

Usb sound card.

 

Does anyone know if those cheap Usb sound card adapters offer any isolation between PC and radio? I plan to try out these things with my isolated interface for digital modes. The plan is to use an Usb to serial adapter for the PTT, and one of these sound card dongles for audio, and a Usb to DIP adapter (exposed PCB) to pick up power for a 5V relay module with opto isolation. All on a 4 way Usb hub. The object is to have one connection to PC. And just hoping I can get away without the audio transformers for the lines in and out.
Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

I heard KD9CYF calling several times. I did not get a response.
Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

No joy here. ?Lots of noise.?

Doug?
KD9CYF?
Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

HAHAH - one of my two QSOs was you!
Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

It were noisy.

I, too, was late to the party - around 7:45 CDT.

I caught two:?

KG5KYJ - SIG 58 or so, BitX to BitX QSO! about 00:45 GMT

KF4WBJ - SIG 54 - could be incorrect, but I *think* that was the call about 00:50 GMT

Wish I'd gotten there earlier, but got busy.

I'll be there with bells on next week.

?

73

Mike Yancey, KM5Z

Dallas, Texas


On Sun, Jun 11, 2017 at 05:43 pm, John Smith wrote:

Well, I am late to the party but I was listening on 7.277 an came running to receive QRM on 7.276. Did we ever agree on a secondary? And I just heard W1LY LOUD and CLEAR trying to contact the QRM in progress. And they moved. de KG5KYJ.

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Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

I heard KG5KYJ in MI but you did not hear me.
Re: BITX40 package size

 

OK, that last post does overstate it a bit.
Dropout through an LM2940* is not zero, it's around 0.130mv at the 150ma draw of the Bitx40 (excluding the IRF510)
With schottky power diodes, drop through a bridge rectifier might get down towards a half volt.
But I think the LM2940* is a win, especially since it limits the voltage to 12v and offers some over-current protection.

Yet another trick is the NDT2955 enhancement mode PFET that Steve Webber uses on the MTR series rigs.
Power from battery goes in on the drain, out on the source to the rig, a 5v zener from source to gate, a resistor from gate to ground.
The PFET's substrate diode conducts when power is first turned on, when there is 5v across the zener the transistor turns on
and does away with the voltage drop across the substrate diode. ?But nothing happens if battery leads are swapped.

More than you wanted to know.

Jerry


On Sun, Jun 11, 2017 at 05:49 pm, Jerry Gaffke wrote:
With the bridge rectifier, you have two unnecessary diode drops. ?So a 12v battery might only deliver 10.5 volts or so to the rig.
The diode and fuse trick avoids the voltage drop, but is a rather brutal approach.
The LM2940* simply shuts down if battery is reversed with no voltage drop penalty, and provides over-voltage protection as well.

?
Re: BITX40 package size

 

With the bridge rectifier, you have two unnecessary diode drops. ?So a 12v battery might only deliver 10.5 volts or so to the rig.
The diode and fuse trick avoids the voltage drop, but is a rather brutal approach.
The LM2940* simply shuts down if battery is reversed with no voltage drop penalty, and provides over-voltage protection as well.

Jerry


On Sun, Jun 11, 2017 at 05:25 pm, Dr Fred Hambrecht wrote:

Even better go through a fuse and have a standard diode between the fuse output and ground. If reversed the diode causes the fuse to blow. Another cure is to feed the input to a bridge rectifier and now it doesn¡¯t matter how you hook it up. I tend to use the bridge approach as the fuse seems to be blow right after the most expensive component in a circuit.

?

?
Re: VK and ZL group buy of Jack W8TEE VFO boards

 

Count me in on 2 please

Regards martin?
VK6FEEE
Re: BITX QSO Night, Sunday, June 11, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere

 

Well, I am late to the party but I was listening on 7.277 an came running to receive QRM on 7.276. Did we ever agree on a secondary? And I just heard W1LY LOUD and CLEAR trying to contact the QRM in progress. And they moved. de KG5KYJ.
Re: BITX40 package size

 

I looked at figure 15 of the LM340 datasheet,
the "shorted input protection diode" is in parallel with the regulator, not in series with it.
The diode addresses a weakness of the LM340: ?if the input of the LM340 suddenly drops to zero
then the output filter caps will discharge through the LM340 to the grounded input pin, with possibly enough current
to destroy the LM340. ?I have not seen that recommended on any modern linear regulators, and doubt it is needed.

Likewise most regulators don't need a protection diode across the output as shown in fig 26
(Though I suppose it could help if the battery leads are reversed, and the regulator does not block reverse voltages
like the LM2940* does, and the diode is big enough to not burn out.)

However, "a 1N400x in series?with the regulator input" as Arv describes it is a very good idea if you can tolerate the diode drop.
That will protect the regulator and everything behind it from reversed battery leads.
Or you could use an LM2940* (pin compatible with the LM7805), which has reverse protection built in,?
but does not pay for it with a significant voltage drop across the device.

Jerry, KE7ER


On Sun, Jun 11, 2017 at 10:28 am, Arv Evans wrote:
45 years ago in the LM340 regulator days it was conventional to always put a 1N400x in series
with the regulator input.? The problem of shorted regulators passing full voltage through them was
well known and accounted for with the series diode.? Somehow we seem to have forgotten that
knowledge over the intervening 40+ years.? Doing this means that you have to account for the
additional 0.65 volts of diode voltage drop, but it is a small price to pay for the added security.

?

The datasheet also shows the shorted-input protection diode across the regulator device (Fig. 15)
and a protection diode across the output (Fig. 26).

Arv K7HKL

?
Re: My Next Ham Radio Project

 

¿ªÔÆÌåÓý

It appears the way you have wired it may be causing a double paraphrase short in the transgronifier. I would suggest a dual direction high Mu diode to enable a neutron acceleration lane.

?

v/r

Fred W4JLE

?

From: [email protected] [mailto:[email protected]] On Behalf Of K-Squared
Sent: Sunday, June 11, 2017 13:32
To: [email protected]
Subject: [BITX20] My Next Ham Radio Project

?

Here's a schematic.? I'll try to include a complete parts list later.

?


?

K2

Women spend more time wondering what men are thinking than men spend thinking.

?
Re: BITX40 package size

 

¿ªÔÆÌåÓý

Even better go through a fuse and have a standard diode between the fuse output and ground. If reversed the diode causes the fuse to blow. Another cure is to feed the input to a bridge rectifier and now it doesn¡¯t matter how you hook it up. I tend to use the bridge approach as the fuse seems to be blow right after the most expensive component in a circuit.

?

v/r

Fred W4JLE

From: [email protected] [mailto:[email protected]] On Behalf Of Arv Evans
Sent: Sunday, June 11, 2017 13:28
To: [email protected]
Subject: Re: [BITX20] BITX40 package size

?

45 years ago in the LM340 regulator days it was conventional to always put a 1N400x in series
with the regulator input.? The problem of shorted regulators passing full voltage through them was
well known and accounted for with the series diode.? Somehow we seem to have forgotten that

knowledge over the intervening 40+ years.? Doing this means that you have to account for the

additional 0.65 volts of diode voltage drop, but it is a small price to pay for the added security.

?

The datasheet also shows the shorted-input protection diode across the regulator device (Fig. 15)
and a protection diode across the output (Fig. 26).

Arv K7HKL
_._

?

On Sun, Jun 11, 2017 at 11:08 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

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


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.

?

?
Re: BITX40 package size

 


From post?/g/BITX20/message/27483

> ?The schematic agrees with how the board is built, so the schematic should remain as it is.
> ?But I agree with K7IOW, looks like an error to me, and that the intent was to wire up K1 same as K2.
> ?Could fix this by cutting the trace from C130 to the nearby ground feedthrough, then wire that end of C130 to the nearest end of C130A1.

That last line should be all you really need to know.
Looking at the schematics, the end result is that the bottom of C130 and D7 have been cut away from ground,
and are now connected to pin 9 of K1.

I'm convinced that is the way it should be.
On the other hand, I have not heard anyone describing trouble that I could attribute to the the lack of a diode across the K1 coil.
So I am not recommending that everybody take a knife to their Bitx40 to do this mod.

Jerry, KE7ER


?

On Sun, Jun 11, 2017 at 04:31 pm, ohwenzelph wrote:
So... for the rest of us, can we (please tell it to me like I'm 5, with specifics) remove D7 and reapply it someplace where "D7 would give the reverse EMF of the K1 coil someplace to go when the PTT switch opens up."? [I have looked at the schematic and I don't understand enough to know what to do, & should you move a cap as well?]

?
Re: VK and ZL group buy of Jack W8TEE VFO boards

 

Hi Bill,

I have a stock Bitx 40 waiting for me to get back into the shack to mod.
My other hobbies are taking my time ... well that and work :-)

I also have one of Jacks boards and ordered an other board last night.
Just waiting on the final parts to get to work.

I thought I would stick my oar in, because I will want the next boards
being developed, so while I will not be ordering this way this time,
I will in future.

Thanks for working this our for us !

Best wishes

Andrew VK6WAM

On 12 June 2017 at 06:50, William R Maxwell <wrmaxwell@...> wrote:

Over the past 24 hours, Jack and I have been in contact off-group about the possibility of setting up a VK source for the W8TEE BITX40 VFO etc pcb, one that could also be accessed by our cousins in NZ.

I am pleased to advise that Jack and I have been easily able to reach agreement. As a result, I will buy a quantity of boards from him at US$7.50 each, plus shipping on whatever quantity I end up ordering. In turn, I will make the boards available to builders here downunder at their cost to me. In other words, the individual board price will be based on equally sharing my costs by simply dividing my total payment to Jack by the number of boards involved.

The price to each participant will then be that unit price per board, plus the actual costs of my posting the order to the builder. Obviously, the final cost will depend upon how many boards the builder requires and the postage cost to that address from VK7 but we confidently predict that ther will be a saving on the cost of ordering directly from Jack. Fortunately, the Australian customs declaration is comparatively simple document and there is never a queue at my local Post Office and we have a free trade agreement, so ZL orders won't be any hardship at this end.

I am travelling over the next 3 days but will reach my home QTH on Wednesday 14 June. I hope to be able to place the order with Jack within a day or so of getting home. If you would like to take part in this group buy please email me direct at vk7mx@wia dot org dot au, removing the spaces and the dots, obviously.

I intend to buy a few spare for future builders, so don't be too concerned if you come across this post later than 14 June.

73

Bill, VK7MX & VK1MX




--
A blessing on your days. A blessing on your life. A blessing on the land.
Re: Raduino V1.01 vs V1.14 Birdie at 7.200

 

I've tried several old versions here on my own BitX40, but I could'nt reproduce your findings.
I can't hear any noticable difference with regards to the tuning clicks or noise from the Raduino.

So I'm puzzled about your findings.

Are you using a standard BITX40 and a standard Raduino?
Did you already install any mods (extra capacitors, shielding, etc) to reduce the noise and tuning clicks?

73 Allard PE1NWL
Re: Hissing sound

 

All you would need is a good ear.
Tune in an SSB station, then fiddle with the new trimmer and the regular tuning control
for best sounding audio. ?That best sounding audio will also show up in your transmitted signal.


On Sun, Jun 11, 2017 at 03:50 pm, EA3IAV wrote:
So in order to know which value I should use i should have equipment such as an oscilloscope...
i may return to previous values...
a shame i already removed the smd cap

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88701 - 88720 of 116829