On Mon, Oct 30, 2017 at 08:07 am, Allard PE1NWL wrote:
While you're waiting for the delivery of the 10T pot, you can already
start with the rest of the modifications.
Although highly recommended, the 10T pot is not strictly required - the
software will still work OK with the standard supplied pot.
Thank you Allard.
I'll come here post some pictures :-)
Good day to all.
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Re: Carrier Null revisited
?e are duiscuissing around BFO carrier leak. As has been explained well that a chip dual diodes are internally balancedenough. Even if suppose one uses discrete diodes,one could minimize but not eliminate carrier leak. It is analogeous to? non exuixtance of 0 and Infinity.
The nulled carrier to one's expectation gets amplified at PA as correctly suggested by Asher Farhan.? but I suppose that we need to make relative measurements. ? sarma
?vu3zmv
?
On Tue, Oct 31, 2017 at 8:27 AM, Raj vu2zap <rajendrakumargg@...> wrote: Grayson,
Measure the DC voltage in both RX and TX modes across C107. It should be zeroif not you will have a carrier
leak.
You complaint that external modulation sounds bad could be something related to the above or simply that
in close proximity you will hear mains hum modulating a carrier. Try a QSO with some near by ham and see.
Raj
At 31/10/2017, you wrote:
>So i heard about the diode/pot replacement, but I can’t even find the dual diode on the board or where R105 used to be.
>
>I am keying the transmitter into a dummy load and monitoring with a scope.? ?I am also listening on a Collins receiver with its antenna disconnected.? The carrier seems way to high but I didn’t write down the exact voltage on the scope.? The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping.
>
>Also, the audio sounds terrible from the little crystal mic.? I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic.? The tone also sounds terrible.? Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
>
>I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board.? In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
>
>Thanks
>KJ7UM Grayson
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Re: Carrier Null revisited
Grayson,
Measure the DC voltage in both RX and TX modes across C107. It should be zeroif not you will have a carrier
leak.
You complaint that external modulation sounds bad could be something related to the above or simply that
in close proximity you will hear mains hum modulating a carrier. Try a QSO with some near by ham and see.
Raj
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At 31/10/2017, you wrote: So i heard about the diode/pot replacement, but I can?�?t even find the dual diode on the board or where R105 used to be.
I am keying the transmitter into a dummy load and monitoring with a scope. I am also listening on a Collins receiver with its antenna disconnected. The carrier seems way to high but I didn?�?t write down the exact voltage on the scope. The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping.
Also, the audio sounds terrible from the little crystal mic. I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic. The tone also sounds terrible. Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board. In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
Thanks
KJ7UM Grayson
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Hi All, I have been thinking of moving the BITX40 to 144 MHz. 144 MHz is a common tunable IF for Microwave Hams. The FT717 is very popular as a tunable IF, however some are still using IC202 and FT290. ? The 144 MHz version of the BITX40 would be a good replacement for the aging IC202 and FT290. ? Comments please. ? 73 Gary vk2kyp ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Tuesday, October 31, 2017 02:58
To: [email protected]
Subject: Re: [BITX20] Raduino as NBFM TX? arv, the original intend was to get a 'toy' FM broadcast transmitter going to provide simultaneous translations for an international conference of organic farmers. the crystal swing wasn't enough to produce a decent audio. then i reprogrammed it work for 145 MHz and it sounded quite reasonable. i must look up the phase modulation schemes in the literature and try them out. ? On Mon, Oct 30, 2017 at 9:18 PM, Arv Evans <arvid.evans@...> wrote: Farhan
Phase modulation was popular with commercial VHF radios in the 1950's era.? Maybe it works best with high impedance resonance?? If that is the case then the modulated stage could be a JFET or MOSFET.? Obviously some room for ? On Mon, Oct 30, 2017 at 9:44 AM, Ashhar Farhan <farhanbox@...> wrote: Arv, I could never get the indirect modulation to work. Perhaps you could play with it. ? On 30 Oct 2017 8:47 pm, "Arv Evans" <arvid.evans@...> wrote: Hans & Farhan
There is always reactance or phase modulation. ? On Mon, Oct 30, 2017 at 6:12 AM, Hans Summers <hans.summers@...> wrote: Hi Farhan Great project! I am surprised that it works, though! I thought the PLL settling time of the Si5351A would be too slow to allow NBFM by applying FM to the reference crystal.? I once tried very quick frequency change commands issued by firmware to the Si5351A but it could not cleanly keep up with more than a few hundred Hz. Let me know though if you find differently! ? On Sun, Oct 29, 2017 at 8:26 PM, Ashhar Farhan <farhanbox@...> wrote: yeah, ? i am trying to figure out the simplest way to get on 2m nbfm. not sure which way to go. ? On Sun, Oct 29, 2017 at 10:48 PM, William R Meara <bill.meara@...> wrote: But remember the admonition of the great Cliff Stoll:? "I guess today's experimenters build things in software, without ever touching a soldering iron. The hocus pocus is inside the program.? It's cleaner this way -- nothing to burn or zap, and you don't need a voltmeter... What happened to home-brewed and breadboarded circuitry? Where's the joy of mechanics and electricity, the creation of real things?? Who are the tinkerers with a lust for electronics? "? ?From "Silicon Snake Oil"? 1995.?? ? On Sun, Oct 29, 2017 at 1:09 PM, Ashhar Farhan <farhanbox@...> wrote: I was thinking that it could be entirely done in software. The audio can be coupled to an analog input of the arduino. The arduino can sample the analog input and accordingly shift the PLL oscillator. I must try that out too.? ? On Sun, Oct 29, 2017 at 6:29 PM, Pete Juliano <jessystems@...> wrote: Very nice. It only gets better. Maybe when 10 Meters comes back there may be an interest in NBFM in gear other than VHF and UHF. Sent: Saturday, October 28, 2017 11:48 PM Subject: Raduino as NBFM TX By adding a couple of components, the Raduino can become a very stable NBFM transmitter. I just blogged my build : This will work equally well with the qrp-labs Si5351 too. ? ? ? ? ? ? ?
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Re: Carrier Null revisited
Grayson KJ7UM wrote... How the heck is a builder supposed to fix carrier
null with no null, AND no way to adjust the BFO
frequency. Did cost reduction make this board
useless for adjustments? I don't think it's a design problem. You are suspecting the diodes. You might be right, but perhaps it would be worth looking at the connections for T4. Perhaps there is a bad solder connection on one of the windings. They should all "work out of the box" but I always figure part of the fun if you are one of the lucky few that have to do some troubleshooting - hi! -- 73 Keith VE7GDH
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Re: Carrier Null revisited
grossly testing my rig tonight (with a receiver right near it) I can hear some carrier also but it doesn't move the SWR or power needle at all on a cheap SWR meter, and whistling I can get several watts (like 60% upscale movement of the meter). So the carrier is many dB below the SSB, just maybe not oodles of dB lower. both of my 2 bitx40's have the combined diode with no adjustment. ________________________________________ From: [email protected] < [email protected]> on behalf of Keith VE7GDH <ve7gdh@...> Sent: Monday, October 30, 2017 9:05 PM To: [email protected]Subject: Re: [BITX20] Carrier Null revisited Grayson KJ7UM wrote... > I can’t even find the dual diode on the board or > where R105 used to be. See the hand drawing that I posted. I marked them D15 / D16 like in the drawing, even though it is a dual-diode in one package. I think Dexter said it is labeled D20 now. I didn't pop the lid to look. I wouldn't be too hasty in removing the diodes though before checking it out a bit further. -- 73 Keith VE7GDH
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Re: Carrier Null revisited
Grayson KJ7UM wrote... I can’t even find the dual diode on the board or
where R105 used to be. See the hand drawing that I posted. I marked them D15 / D16 like in the drawing, even though it is a dual-diode in one package. I think Dexter said it is labeled D20 now. I didn't pop the lid to look. I wouldn't be too hasty in removing the diodes though before checking it out a bit further. -- 73 Keith VE7GDH
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Re: Carrier Null revisited
The dual-diode is labelled D20 on the board, and it's inside the triangle formed by the pads for a large version of the Pot - which is depicted. D20 is obscuring the wiper pad for the smaller (standard) version of the pot, which is the same style as R136 the Tx drive pot. The whole shebang sits next to the toroid (that looks like a 6-pin IC) bottom-left on the Wire Up picture on hfsigs site.
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Re: Board Layout Drawing?
Grayson KJ7UM wrote… Is there a drawing someplace that shows component placement on the board? Attached is a very crude hand-drawn component placement drawing. It doesn’t show every part, but has the transistors etc. marked, so it might be enough to direct you to the right vicinity. Let me know if the resolution is too low. -- 73 Keith VE7GDH
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Re: Carrier Null revisited
On Mon, Oct 30, 2017 at 01:58 pm, Grayson Evans wrote:
So i heard about the diode/pot replacement, but I can’t even find the dual diode on the board or where R105 used to be.
My own board is nearly one year old and it still has the balance pot installed. Could you perhaps make a photo of this area on your BitX board and share it with us? I'm sure someone in this group will be able to identify the dual diode for you. 73 Allard PE1NWL
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Re: Need picture of 8 pin connector
Thank you all for your help.?
Bill?
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Re: Need picture of 8 pin connector
The 8-pin connector on the *Raduino* attaches through to the A lines of the *Arduino*. On <http://www.hfsigs.com/bitx40v3_circuit.html>, at the Bottom of the page is the explanation: it's the CONTROLS connector. Note that the numbering there is reversed, but in order (with a gap or two). A0 is the right-most, and the A numbers increase leftwards. The plug as supplied with loom wiring has the wires color-coded per the Resistor color code: 0 is black, 1 is brown ... Yellow and green are +5 and 0V, taking the A4 and A5 places, purple (I call it violet, it's my NZ Post Office loom-colour naming, just like grey is slate ...) is to A7. The other 'looms' are similarly coded, but the colors are as per the diagram *minus one*! Pin 1 has the black (0) wire ... It's logical, with a bit of mental arithmetic.
73 de ZL2DEX
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Re: Need picture of 8 pin connector
BTW, one easy way to remember the colours:
It's just the same as the colour code as used on resistors:
0 - black
1 - brown
2 - red
3 - orange
4 - yellow
5 - green
6 - blue
7 - violet
73 Allard PE1NWL
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On Mon, October 30, 2017 22:52, Allard PE1NWL wrote:
pin A2 noramally has the red wire (not shown on the picture)
73 Allard PE1NWL
On Mon, October 30, 2017 22:46, W4YAH@... wrote:
I need a picture of the 8 pin connector so I can re-attach the wires to
calibrate my BITX40.??
THANKS,??
BILL, W4YAH
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Re: Need picture of 8 pin connector
pin A2 noramally has the red wire (not shown on the picture)
73 Allard PE1NWL
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On Mon, October 30, 2017 22:46, W4YAH@... wrote: I need a picture of the 8 pin connector so I can re-attach the wires to
calibrate my BITX40.??
THANKS,??
BILL, W4YAH
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Need picture of 8 pin connector
I need a picture of the 8 pin connector so I can re-attach the wires to calibrate my BITX40.?
THANKS,?
BILL, W4YAH?
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Re: Carrier Null revisited
I agree. ?I should have written down the levels. ?I will do that when I get home tonite and post it. ?
I am just grounding the PTT line to key it, no microphone attached.?
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On Oct 30, 2017, at 2:44 PM, Gordon Gibby < ggibby@...> wrote:
I think we need some numbers here. What is the gentleman's peak output, measured and whatever method he has, either watts, or even a relative reading on some swr or other indicator....
Exactly how is he "keying" the machine, does he mean he is closing the push to talk?
What is the output (on the same measurement system as above) when there is no audio mic signal??
At least then we would have some idea of whether his carrier level is zero, five, 10, or more DB below his peak output.
"A lot" it's just terribly vague.....
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Re: Carrier Null revisited
I will definitely try this.
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I remember that Farhan posted something a while back that said if you are driving the PA too hard you will see some carrier.
Decrease the PA drive (RV136) a bit and it should go away.?
Michael VE3WMB?
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Re: Carrier Null revisited
So i heard about the diode/pot replacement, but I can’t even find the dual diode on the board or where R105 used to be.
I am keying the transmitter into a dummy load and monitoring with a scope. ? I am also listening on a Collins receiver with its antenna disconnected. ?The carrier seems way to high but I didn’t write down the exact voltage on the scope. ?The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping. ?
Also, the audio sounds terrible from the little crystal mic. ?I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic. ?The tone also sounds terrible. ?Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board. ?In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
Thanks KJ7UM Grayson
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On Oct 30, 2017, at 2:28 PM, Jerry Gaffke via Groups.Io < jgaffke@...> wrote:
Most of these seem to have the carrier pretty well suppressed without adjustment.
The change to the dual-diode bat54s was made to avoid the need for such an adjustment,
since the two schottky diodes in that package are on the same die and at the same temperature,?
thus well matched. ?Unfortunately, the two diodes in the bat54s are joined where the bitx40 schematic?
shows the 100 ohm pot, so the pot won't work with the bat54s. ?There are other diode arrays
where they are on the same die but have the two diodes separated out.
Schottky or a standard 1n4148 silicon diode both seem to work fine.
Should be easy enough to remove the bat54s and add back in a couple diodes and a 100 ohm pot,
if that's what you want. ?Though my guess is that there may be something else wrong here.
Exactly how are you measuring the carrier level on your transmissions?
Yes, you will be able to hear it on a receiver in the same area, but it typically is not strong enough
to be of any concern.
Jerry
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Re: Carrier Null revisited
I think we need some numbers here.
What is the gentleman's peak output, measured and whatever method he has, either watts, or even a relative reading on some swr or other indicator....
Exactly how is he "keying" the machine, does he mean he is closing the push to talk?
What is the output (on the same measurement system as above) when there is no audio mic signal??
At least then we would have some idea of whether his carrier level is zero, five, 10, or more DB below his peak output.
"A lot" it's just terribly vague.....
Sent from my iPhone
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>From:?Grayson
Evans
>Date: Mon, 30 Oct 2017 12:35:00 EDT?
>Just finished building out a new BITX40 board. Works, but there is a LOT of carrier when keyed (no mic installed).?
I remember that Farhan posted something a while back that said if you are driving the PA too hard you will see some carrier.
Decrease the PA drive (RV136) a bit and it should go away.?
Michael VE3WMB?
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Re: Carrier Null revisited
>From:?Grayson Evans>Date: Mon, 30 Oct 2017 12:35:00 EDT?>Just finished building out a new BITX40 board. Works, but there is a LOT of carrier when keyed (no mic installed).?
I remember that Farhan posted something a while back that said if you are driving the PA too hard you will see some carrier. Decrease the PA drive (RV136) a bit and it should go away.?
Michael VE3WMB?
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F1NQP JanJack
Raj vu2zap
Allard PE1NWL
BillBolen