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Date

Re: KB1GMX on the BITX

 

Yup. ?When operating the VFO down around 5mhz we get images of SW Broadcasters from the 4'th harmonic of the vfo, as first explained by PA4Q in post 21996. ?As you suggest, 7.2mhz gets received twice, once as LSB and once as USB.

As a separate issue explained in post 21941, we get a birdie at 7.2mhz from the 5'th harmonic of the 4.8mhz vfo beating with the 2'd harmonic of the 12mhz BFO.

The above two have both been complained about mightily over the last month or so.

We can avoid both if we move the VFO up to the high side as per your recommendation. ?However, as noted in post 22005, the 8'th harmonic of the bfo can beat with the 5'th harmonic of the vfo, giving us a birdie at 7.2mhz. ? ?(Likely faint if there at all, and shielding the bfo/demodulator should kill it.)

Conclusion: ?7200000 is an extremely inauspicious number for this radio.?

Jerry, KE7ER


On Mon, Feb 20, 2017 at 07:09 am, <ajp166@...> wrote:

The likely problem is interaction between the BFO and the LO causing a result at 7.2 when tuned to 7.2.

?


Re: Unbalancing mixer

 

Using the digital chip for the bfo sounds like the answer but I know nothing about programming the Arduino and the digital chip so I'll have to wait until someone smarter decides to tackle it! ?:-))

Roy
WA0YMH

On Feb 20, 2017 9:39 AM, "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]> wrote:

Will work fine if you move the BFO a khz over into the crystal filter passband.? Trivial if the BFO is driven from a second channel of the Si5351, and gives us a better option for USB/LSB switching as well.? If you insist on analog, perhaps a varactor diode in the BFO as used on the analog vfo.

See post?/g/BITX20/message/20933

Still no Bitx40 here though.


On Mon, Feb 20, 2017 at 06:59 am, Roy Appleton wrote:

So that means that unbalancing the mixer will never be a legitimate way to introduce a carrier for tuning purposes?
? On Feb 19, 2017 10:37 PM, "Ashhar Farhan" <farhanbox@...> wrote:
The center tap that takes the audio from the mic. A caveat though, the carrier is on the skirt rather than in the center of the filter.

?


Re: Unbalancing mixer

 

Will work fine if you move the BFO a khz over into the crystal filter passband. ?Trivial if the BFO is driven from a second channel of the Si5351, and gives us a better option for USB/LSB switching as well. ?If you insist on analog, perhaps a varactor diode in the BFO as used on the analog vfo.

See post?/g/BITX20/message/20933

Still no Bitx40 here though.


On Mon, Feb 20, 2017 at 06:59 am, Roy Appleton wrote:

So that means that unbalancing the mixer will never be a legitimate way to introduce a carrier for tuning purposes?
? On Feb 19, 2017 10:37 PM, "Ashhar Farhan" <farhanbox@...> wrote:
The center tap that takes the audio from the mic. A caveat though, the carrier is on the skirt rather than in the center of the filter.

?


Re: KB1GMX on the BITX

 

The likely problem is interaction between the BFO and the LO causing a result at 7.2 when tuned to 7.2.

I used a SI70 and a crystal osc based on a spare crystal from builidng the filter for the BFO so I could

isolate them and it was not an issue. ? Note I tried an actual 19mhz VFO and it worked fairly well but

required really good construction to be stable. ?FYI there were/are commercial radio that use high

VFOs namely Tentec Argonaut 505 and Atlas 180/210/215 and with good construction and temperature

compensation I can say they work as I have both. ?It does take some effort and I've built a VFO at 14mhz

that was very stable but mechanically involved.


That brings up a possible issue. ?Long wires connecting things and shielding of stray signals. ?Care is required there

as the NCO can and will radiate is the wires are somewhat random.


--
Allison/KB1GMX


Re: Need help with constant tone in audio output

ken barnes
 

try large capasitor ie ?50uf ?25 volt working ? ? across power supply.............


On Monday, 20 February 2017, 13:51, Raj vu2zap <vu2zap@...> wrote:


FIrst I am suspecting the power supply.

Second disconnect the volume plug and see, I would suspect the tone will be there if the PS is at fault.

Third If the tone stops then suspect the preamp transistor or earlier.

As you said you have disconnected the rest.

Raj



At 20/02/2017, you wrote:

Good morning Jerry and the group,

Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise.

73,
Chuck K3VPZ


From: "Jerry Gaffke via Groups.Io" <jgaffke@...>
To: [email protected]
Sent: Sunday, February 19, 2017 4:59:53 PM
Subject: Re: [BITX20] Need help with constant tone in audio output

Did you enable the analog vfo by adding L4?

If the tone is still there with no vfo, that's a hint


On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote:
Have disconnected the Raduino, tone still there.

?



Re: Unbalancing mixer

 

So that means that unbalancing the mixer will never be a legitimate way to introduce a carrier for tuning purposes?


Roy
WA0YMH


On Feb 19, 2017 10:37 PM, "Ashhar Farhan" <farhanbox@...> wrote:
The center tap that takes the audio from the mic. A caveat though, the carrier is on the skirt rather than in the center of the filter.
- f

On 20 Feb 2017 7:58 a.m., "Ken" <chase8043@...> wrote:
4.7K resistor from center tap of R106 to 12 volts?

73

Ken VA3ABN

On Sun, Feb 19, 2017 at 8:40 AM, Ashhar Farhan <farhanbox@...> wrote:
You can inject a few millamps into the modulator at the center tap.
- f

On 19 Feb 2017 7:09 p.m., "Ken" <chase8043@...> wrote:
How do I go about unbalancing the mixer to produce a carrier?

I know that R106 balances the mixer for no carrier. So I assume a small value resistor to unbalance it.

73

Ken VA3ABN



Re: Calibration

Jack Purdum
 

I also have that case, too, but I'm adding a Muppet board and there wasn't enough room for both in the Banggood case. It is, however, a very nice case.

Jack, W8TEE



From: Buck <RadioK4ia@...>
To: [email protected]
Sent: Monday, February 20, 2017 9:26 AM
Subject: Re: [BITX20] Calibration

A similar case is on Banggood but check the dimensions.



Buck, k4ia
Honor Roll
8BDXCC

On 2/20/2017 9:13 AM, Jack Purdum via Groups.Io wrote:
> I was looking for the order, but can't find it. The supplier was Allied
> Electronics and the case was:
>
>
>
> They have a bazillion cases. If I can confirm the order, I'll post it to
> the group.
>
> Jack, W8TEE
>
>
> ------------------------------------------------------------------------
> *From:* Leo de Blaauw <L.deblaauw@...>
> *To:* [email protected]
> *Sent:* Monday, February 20, 2017 1:45 AM
> *Subject:* Re: [BITX20] Calibration
>
> Hi Jack,
>
> Slightly off-topic, but may I ask what enclosure you are using ?
>
> regards and 73
> Leo de Blaauw - PD1LDB
>
>






Re: Calibration

 

A similar case is on Banggood but check the dimensions.



Buck, k4ia
Honor Roll
8BDXCC

On 2/20/2017 9:13 AM, Jack Purdum via Groups.Io wrote:
I was looking for the order, but can't find it. The supplier was Allied
Electronics and the case was:



They have a bazillion cases. If I can confirm the order, I'll post it to
the group.

Jack, W8TEE


------------------------------------------------------------------------
*From:* Leo de Blaauw <L.deblaauw@...>
*To:* [email protected]
*Sent:* Monday, February 20, 2017 1:45 AM
*Subject:* Re: [BITX20] Calibration

Hi Jack,

Slightly off-topic, but may I ask what enclosure you are using ?

regards and 73
Leo de Blaauw - PD1LDB


Re: Need help with constant tone in audio output

 

Good morning Larry,

Success! Using a battery cleared up the tone. Now on to packing it up in its enclosure. Many thanks to all for helping including Jerry!

73,
Chuck K3VPZ


From: "Larry Acklin" <acklin@...>
To: [email protected]
Sent: Monday, February 20, 2017 8:30:31 AM
Subject: Re: [BITX20] Need help with constant tone in audio output

Try a battery supply.? My shack supply does not play nice with the BitX.? A small wall wart 2A, 12V is silent.? I get tone with the shack PS.

Larry
KB3CUF

On Mon, Feb 20, 2017 at 8:01 AM, Chuck <chucke2@...> wrote:
Good morning Jerry and the group,

Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise.

73,
Chuck K3VPZ


From: "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]>
To: [email protected]
Sent: Sunday, February 19, 2017 4:59:53 PM
Subject: Re: [BITX20] Need help with constant tone in audio output

Did you enable the analog vfo by adding L4?

If the tone is still there with no vfo, that's a hint


On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote:

Have disconnected the Raduino, tone still there.

?





Re: Calibration

Jack Purdum
 

I was looking for the order, but can't find it. The supplier was Allied Electronics and the case was:?


They have a bazillion cases. If I can confirm the order, I'll post it to the group.

Jack, W8TEE



From: Leo de Blaauw <L.deblaauw@...>
To: [email protected]
Sent: Monday, February 20, 2017 1:45 AM
Subject: Re: [BITX20] Calibration

Hi Jack,

Slightly off-topic, but may I ask what enclosure you are using ?

regards and 73
Leo de Blaauw - PD1LDB


Re: Need help with constant tone in audio output

 

FIrst I am suspecting the power supply.

Second disconnect the volume plug and see, I would suspect the tone will be there if the PS is at fault.

Third If the tone stops then suspect the preamp transistor or earlier.

As you said you have disconnected the rest.

Raj



At 20/02/2017, you wrote:

Good morning Jerry and the group,

Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise.

73,
Chuck K3VPZ


From: "Jerry Gaffke via Groups.Io" <jgaffke@...>
To: [email protected]
Sent: Sunday, February 19, 2017 4:59:53 PM
Subject: Re: [BITX20] Need help with constant tone in audio output

Did you enable the analog vfo by adding L4?

If the tone is still there with no vfo, that's a hint


On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote:
Have disconnected the Raduino, tone still there.

?


Re: Need help with constant tone in audio output

 

Try a battery supply.? My shack supply does not play nice with the BitX.? A small wall wart 2A, 12V is silent.? I get tone with the shack PS.

Larry
KB3CUF

On Mon, Feb 20, 2017 at 8:01 AM, Chuck <chucke2@...> wrote:
Good morning Jerry and the group,

Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise.

73,
Chuck K3VPZ


From: "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]>
To: [email protected]
Sent: Sunday, February 19, 2017 4:59:53 PM
Subject: Re: [BITX20] Need help with constant tone in audio output

Did you enable the analog vfo by adding L4?

If the tone is still there with no vfo, that's a hint


On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote:

Have disconnected the Raduino, tone still there.

?




Re: Need help with constant tone in audio output

 

Good morning Jerry and the group,

Had to stop last night, having probed for nearly 10 hours. Jerry, my trouble shooting is hampered by not having an up-to-date schematic. My board is a Bitx40 V3. It's interesting to note that when I power the '40 up the tone is immediate and the rcvr comes on about a second later. I have all the components taken out of the '40 except the volume control... still the tone. I wonder if India could replace the board given the amount of time spent trying to get it working? I'll continue to trouble shoot today and will keep you and the group updated. BTW, the tone encountered is not a clicking noise.

73,
Chuck K3VPZ


From: "Jerry Gaffke via Groups.Io" <jgaffke@...>
To: [email protected]
Sent: Sunday, February 19, 2017 4:59:53 PM
Subject: Re: [BITX20] Need help with constant tone in audio output

Did you enable the analog vfo by adding L4?

If the tone is still there with no vfo, that's a hint


On Sun, Feb 19, 2017 at 01:07 pm, <chucke2@...> wrote:

Have disconnected the Raduino, tone still there.

?



Re: BITX40

 

The current drawn will depend upon the peak to average ration of the voice characteristics which is different for every individual.
That is why a speech processor would be a great help to maintain a quasi-constant level.
Regards
Lawrence

On Mon, Feb 20, 2017 at 2:50 AM, John Smith via Groups.Io <johnlinux77@...> wrote:

Update: Mine still does that quiet clicking thing. It's just less prominent now. And still jittery on last digit, like I said.?

And I wanted to check the current draw of the PA with the 20V supply. I found that R136 doesn't do much at 20V. When I experimented with R136 at 12V it made all the difference in the world. But the no audio current draw was 90mA and long aahhh current draw was as much as 1.3 Amps. Just something about that note in my voice makes it peak high, and normal talking is around 750mA. So, current draw is about the same, going from 12V to near max of 24V. No need to recalibrate after doing it at 12V.



Re: BITX40

 

It is standard practice that to eliminate any source of noise the decoupling has to be as near the source as possible using capacitors suitable for the frequency/ies involved.
This also aids stability.
Shielding of the readout and its wiring will also help.
Using shielded cables including in the audio stages is also standard practice.
Regards
Lawrence

On Sun, Feb 19, 2017 at 3:30 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

I don't think I could put up with the freq jumping around like that, should have a bit of hysterisis in raduino code.? So you have to reverse direction 2 or 3 clicks before anything happens.? Somebody in a recent post found that putting the supplied 0.1uf cap on the raduino pins instead of at the tuning pot on the other end of the wires made it behave somewhat better.? I might eventually go to the shuttle tuning scheme described by Don Cantrell here: ?


On Sat, Feb 18, 2017 at 06:07 pm, John Smith wrote:

Mine did this too. When the frequency readout is flicking back and forth there is a corresponding click. When the readout is not flicking a quieter clicking sound can still be heard until I keep fiddling with the knob to get the freq steady, then it's all quiet. It's like the clock generator is changing frequency in small enough amounts that it doesn't change the display. But then after changing the tuning poteniometer for a smaller one with a knurled shaft, it doesn't do that anymore. The freq still flicks back and forth like it did before, but no more quiet clicking. I just did this for a more convenient knob choice.? I also noticed before, that when it does that quiet clicking, my transmitted signal would also waver back and forth in freq while I monitored with a receiver.

?



Re: KB1GMX on the BITX

 

Hi,


Has anyone had any success in getting the bitx40 running with VFO at 19Mhz?


I tried last night and observations were:

Drive out of the raduino needed to increase to 4ma before any noise came out of the receiver.

Frequency measured at the output of Q7 was not 19Mhz???

Tested BFO at both 11.9985 and 12.0015 made no difference to resolving a signal. I have a trimmer cap at the BFO. C103.

I'm wondering if the normal pins are the right place to inject the VFO.

And there was still a birdie at 7.200Mhz- with no antenna just dummy load.?


Also, varying the BFO varies the frequency of the birdie at 7.2Mhz for both VFO frequencies.


Another observation, the birdie was louder with increased drive out of the raduino.


Regards

Simon VK3ELH ?


Re: BFO Location

 

You will find a single 12Mhz xtal with some components next to the 860 - thats the bfo.

73 Raj

At 20/02/2017, you wrote:

Hi,

I'm having a bit of trouble locating the BFO on the bitx40 board to take some measurements. From looking at the circuit diagram it seems to be around the LM386 or D15, is that correct? I'm just a tad bit confused where it's hiding!

Thanks,

KM4ZCT


Re: KB1GMX on the BITX

 

Hi? John ,

I?? agree with the explanation for 100% .
This is also my ecperience

Marco , France


Re: Calibration

 

Hi Jack,


Slightly off-topic, but may I ask what enclosure you are using ?


regards and 73

Leo de Blaauw - PD1LDB


BFO Location

 

Hi,

I'm having a bit of trouble locating the BFO on the bitx40 board to take some measurements. From looking at the circuit diagram it seems to be around the LM386 or D15, is that correct? I'm just a tad bit confused where it's hiding!

Thanks,

KM4ZCT