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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

?
Re: BITX40 package size

 

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?]

thanks (really!)
jerry terres AA1OF?
VK and ZL group buy of Jack W8TEE VFO boards

 

¿ªÔÆÌåÓý

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
Re: Hissing sound

EA3IAV
 

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
Re: Solder fume filter

 

You can still get rosin core solder.
Using that stuff is like burning incense.?

If vaporized lead has been an issue all these years, I'm done for.
Could explain a lot.

Jerry, ?KE7ER



On Sun, Jun 11, 2017 at 02:57 pm, Doug W wrote:
Any suggestions for a cheap, effective benchtop solder fume filter. ? Currently I use my bench in the garage but I'd like to move into the house. Of course to do this I have to be smoke and odor free. ?

?
Re: Hissing sound

 

Changing the capacitance at C102/C103 will adjust the frequecy of the BFO, , typically at 11.998500 mhz.
Farhan found that with 47pf at C102 and with all five 12mhz crystals matched, the BFO was placed correctly with respect to the crystal filter for LSB use.
There are reports that some get better audio if the frequency of the BFO is adjusted a few hundred hz from that point.
However, the value that worked for Peter may not be the value you need on your rig.

If you wish to vary the BFO frequency for better audio, I suggest you change out C102 and add a trimmer capacitor at C103.
The 47pf Farhan settled should be within the range of C102+C103, your setting for best audio might be above or below Farhan's 47pf value.
For example, perhaps remove C102 and put a 100pf trimmer at C103.
Or put a 20pf cap at C102 and a 50pf trimmer at C103.



A better solution would be to drive the BFO from CLK0 of the Si5351 as is done on the uBitx,
then we could add code to the sketch to adjust the BFO frequency from the calibration routine.?

Jerry, KE7ER


On Sun, Jun 11, 2017 at 02:35 pm, EA3IAV wrote:
I have noticed that when intouched with the tester probe into the the sound from the speaker become louder.
So, i decided to try this mod that Peter showed o his video

?
Re: Frequency from dds pcb

OZ9AEW
 

if you have place your Bitx40 for 7.0000 on display and you han a reading about 5 MHz just say ( reading*5 )
and place result in this line :

?si5351.init(SI5351_CRYSTAL_LOAD_8PF, 24994650L,0); ( 24994650 is my result line normal say 25000000L

diff. from display readout an "real" freq. is less then 100hz?
Re: Solder fume filter

 

¿ªÔÆÌåÓý

Thanks much, I didn't realize they were that inexpensive. ?Might add a light and magnifier to the one on an adjustable arm.

"Re: Solder fume filter?

From: David McGough

Date: Sun, 11 Jun 2017 17:13:08 CDT?

These are the best "cheap" filters I've seen--adequate for casual?

work. I've got models similar to both of these.?


. . . "
Re: Solder fume filter

 

These are the best "cheap" filters I've seen--adequate for casual
work. I've got models similar to both of these.






They're certainly better than just a fan!


73, David KB4FXC

On Sun, 11 Jun 2017, Doug W wrote:

Any suggestions for a cheap, effective benchtop solder fume filter. ?? Currently I use my bench in the garage but I'd like to move into the house. Of course to do this I have to be smoke and odor free.
Solder fume filter

 

Any suggestions for a cheap, effective benchtop solder fume filter. ? Currently I use my bench in the garage but I'd like to move into the house. Of course to do this I have to be smoke and odor free. ?
Re: Hissing sound

EA3IAV
 

I have noticed that when intouched with the tester probe into the the sound from the speaker become louder.
So, i decided to try this mod that Peter showed o his video


Although all I could get was this 33+18p caps it sounds good to me

IMG_4082.PNG
IMG_4082.PNG

Re: Calling West Coast BITX operators

 

Jonathan KK6RPX wrote...

Just curious, how many West Coast BITX operators
are on this list?
I ordered a BITX40 on June 2. It will be used on
Salt Spring Island, BC.

It was after ordering a hot air soldering station
that I started looking for SMD QRP kits that I came
across the BITX40.

I almost sent my first post off yesterday. I had
downloaded the Raduino INO file and was attempting
to compile it but kept getting error messages. I
finally figured out I needed the Si5351 library,
although from what I've read, I might have go
looking for an older version. This will be my first
time doing anything with an Arduino.

The first step will be to get it all put together
and working, but adding CW and AGC might be nice
additions.

I'll try and listen on 7277 KHz this evening, but
it won't be on a BITX40 yet. I can turn the power
down, but I will be guessing at the actual power
level.

--
73 Keith VE7GDH
Re: New BITX-40 User and Antenna Recommendations

EA3IAV
 

I have this one
good on rx but poor on tx

whizz loop antenna by moonraker
there are two versions starting from 7 or 14mhz
Re: New BITX-40 User and Antenna Recommendations

 

A really cheap and simple option worth trying is an indoor dipole. ? Check out this page, , and omit the 20m radials since you're only using it for the bitx40.? I have something similar installed in my house... although I haven't used it much (I spend too much time doing homework right now... not enough playing with radios), I was able to hear stuff on it when I first set it up. ?

IMG_20170611_133019.jpgYou'd need some kind of swr meter to trim it to the correct length, but that's it. ??

--Dan
KK6WCG
IMG_20170611_133019.jpg


On Sun, Jun 11, 2017 at 11:33 AM Thomas Noel <tnoel@...> wrote:
Both will work, and both will have similar challenges as you can¡¯t fool Mother Nature.

The (extremely) short loaded vertical will have low efficiency and narrow bandwidth, and will require a tuner.

The magnetic loop will also have extremely narrow bandwidth and require adjustment with even slight frequency changes.

Google K2MIJ and his extremely small antennas for HF, such as the 9¡± tall ¡°Limbo Stick¡±

Another idea is the spiral loop.

Thomas W Noel
KF7RSF

On Jun 11, 2017, at 11:15 AM, Syed Faisal Akber <faisal@...> wrote:

Hi Everyone,

I ordered a BITX-40 a short while ago (A3-720).? I've finally wired it together and got it working!!

Once I have a decent small antenna I'll get on the air.? I live in an apartment and won't be able to put up dipoles or large verticals.

I am looking at two different options:
1 - A short (2m) vertical with a loading coil.
2 - A small magnetic loop.

Have you tried the BITX-40 with any of these two types of antennae?

What are your experiences and recommendations?

Thanks and 73,
VA3SFA/W6
Re: BITX40 package size

 

The NPN's powered from the "TX" 12v rail do not get power unless the PTT switch is pressed to transmit.
I suggest you concentrate on the receiver first.
When checking out the transmitter, no need to apply power to the IRF510 ?until everything else is working.
Should be able to hear a 40m transmission from just the Q14 driver, using?a nearby shortwave receiver.


On Sun, Jun 11, 2017 at 01:30 pm, Jerry Gaffke wrote:
Raj's advice to check the base-emitter voltage across all those NPN transistors is a good one,
just unplug the Raduino and look for around 0.7 volts on each NPN with a DC voltmeter.

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