Date   
Re: interesting receiver chip

Ziggy
 

Arrow apparently has 13 in stock at the moment, for $10.17 each. And in SSOP not QFN :)

Also, the Si4734 looks to be the same, but without RDS support. No idea if the 'SSB Patch' is available for that device or if you could use the same one.

Cheers!

K9MR

Re: interesting receiver chip

Vojtech Bubnik
 

https://www.dropbox.com/sh/xzofrl8rfaaqh59/AADzNmy03ChAllQ_cA0sq_Qpa/si4735_SSB_NBFM_programming_guide_20120831.pdf?dl=0

SSB audio bandwidth 1.2kHz, 2.2kHz, 3kHz, 4kHz
CW audio bandwith: 500Hz, 1kHz

various AGC configurations
tuning step 1kHz (likely this is the PLL tuning step) + digital BFO (from -16383Hz to +16373Hz)

This looks like some HAM employee of SiLabs wrote it for himself.

Re: interesting receiver chip

bleepingbeep
 

Haha--I know you meant "Tecsun", Joel. Gave me pause, though.

Jerry AA6KI
Tucson

Re: interesting receiver chip

Vojtech Bubnik
 

Re: interesting receiver chip

 

I have the CountyComm radio also and use it every morning, it is a great receiver. I hear the Tucson PL-660 uses that chip also and is another great radio.

Joel 
N6ALT

On Mar 4, 2020, at 8:25 AM, n2msqrp <mstangelo@...> wrote:


This chip is used in this radio:


For a small $90 dollar radio it does a good job. I have two of them and I can pick up the local 40 meter day nets, such as ECARS, with a 6 foot piece of wire.

Mike N2MS


On March 4, 2020 at 9:11 AM Steven Weber <steve.kd1jv@...> wrote:

As a broadcast receiver, it doesn’t need to be very sensitive.

Mouser doesn’t stock the Si4735. Bummer. The only Si Rx chip Mouser has in stock is the Si4840, which only does the FM and AM broadcast band, uses analog tuning and costs US13.00 in singles. The Si4844 does SWBC in 5 kHz steps, but is non-stocked.

 

https://www.silabs.com/documents/public/data-sheets/Si4730-31-34-35-D60.pdf
page 15
Sensitivity when (S+N)/N = 26 dB: typical 25µV EMF
whatever it means

I am not sure what these numbers mean. Those 25uV at SNR 26dB correspond to 2.5uV at SNR 6dB, but this SNR applies to a wideband AM. Maybe the numbers will look better for a narrow band SSB or CW filter.

https://en.wikipedia.org/wiki/S_meter
S8 25.1uV RMS
S5 3.2uV
S4 1.6uV

 

 


 

Re: interesting receiver chip

Vojtech Bubnik
 

Re: interesting receiver chip

n2msqrp
 

This chip is used in this radio:


For a small $90 dollar radio it does a good job. I have two of them and I can pick up the local 40 meter day nets, such as ECARS, with a 6 foot piece of wire.

Mike N2MS


On March 4, 2020 at 9:11 AM Steven Weber <steve.kd1jv@...> wrote:

As a broadcast receiver, it doesn’t need to be very sensitive.

Mouser doesn’t stock the Si4735. Bummer. The only Si Rx chip Mouser has in stock is the Si4840, which only does the FM and AM broadcast band, uses analog tuning and costs US13.00 in singles. The Si4844 does SWBC in 5 kHz steps, but is non-stocked.

 

https://www.silabs.com/documents/public/data-sheets/Si4730-31-34-35-D60.pdf
page 15
Sensitivity when (S+N)/N = 26 dB: typical 25µV EMF
whatever it means

I am not sure what these numbers mean. Those 25uV at SNR 26dB correspond to 2.5uV at SNR 6dB, but this SNR applies to a wideband AM. Maybe the numbers will look better for a narrow band SSB or CW filter.

https://en.wikipedia.org/wiki/S_meter
S8 25.1uV RMS
S5 3.2uV
S4 1.6uV

 

 


 

Re: interesting receiver chip

Vojtech Bubnik
 

Re: interesting receiver chip

Steven Weber
 

As a broadcast receiver, it doesn’t need to be very sensitive.

Mouser doesn’t stock the Si4735. Bummer. The only Si Rx chip Mouser has in stock is the Si4840, which only does the FM and AM broadcast band, uses analog tuning and costs US13.00 in singles. The Si4844 does SWBC in 5 kHz steps, but is non-stocked.

 

https://www.silabs.com/documents/public/data-sheets/Si4730-31-34-35-D60.pdf
page 15
Sensitivity when (S+N)/N = 26 dB: typical 25µV EMF
whatever it means

I am not sure what these numbers mean. Those 25uV at SNR 26dB correspond to 2.5uV at SNR 6dB, but this SNR applies to a wideband AM. Maybe the numbers will look better for a narrow band SSB or CW filter.

https://en.wikipedia.org/wiki/S_meter
S8 25.1uV RMS
S5 3.2uV
S4 1.6uV

 

Re: interesting receiver chip

Vojtech Bubnik
 

https://www.silabs.com/documents/public/data-sheets/Si4730-31-34-35-D60.pdf
page 15
Sensitivity when (S+N)/N = 26 dB: typical 25µV EMF
whatever it means

I am not sure what these numbers mean. Those 25uV at SNR 26dB correspond to 2.5uV at SNR 6dB, but this SNR applies to a wideband AM. Maybe the numbers will look better for a narrow band SSB or CW filter.

https://en.wikipedia.org/wiki/S_meter
S8 25.1uV RMS
S5 3.2uV
S4 1.6uV

Re: interesting receiver chip

Steven Weber
 

I saw that pop up on my FB feed but didn’t investigate it. I should now.

Steve KD1JV

 

 

especially for Steve: did you see the following single chip receiver solution?

It seemingly could decode both CW and SSB.

 

73, Vojtech OK1IAK

 

 

interesting receiver chip

Vojtech Bubnik
 

especially for Steve: did you see the following single chip receiver solution?
It seemingly could decode both CW and SSB.

73, Vojtech OK1IAK

Re: New file uploaded to kd1jvdesigns@groups.io

Steven Weber
 

No, if by V.1 you mean the first SB with the led display. If you mean SB II with the LCD display, then yes.

 

Steve KD1JV

 

 

Folks,
may this sketch be used for the SlopBucket v.1 ? Does it need a reconfiguration?
Inquiring minds wanna know.
jon, ea2sn / ae2sn

 

Re: New file uploaded to kd1jvdesigns@groups.io

Jon EA2SN
 

Folks,
may this sketch be used for the SlopBucket v.1 ? Does it need a reconfiguration?
Inquiring minds wanna know.
jon, ea2sn / ae2sn

Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

Thanks to both of you.

I first tried to change C67 to 22pF as suggested by Steven. I did not see a difference at all, so I skipped the 2nd suggestion (changing it to a resistor) and went immediatelly
to Don's idea about changing everything (C60-62 and C67) to 10pF.

And that did the trick. Now i had the same output on USB and LSB ( I just noticed that in the SB1 C67 really was an 1k resistor - so this might havealso  been enough).

I know of course that there is no real usage for LSB on 20m, but since  this was the mode that worked, I used it for reference. I just needed something to compare to.


This change  also helped a lot with the RX sensitivity. Today I used the calibration station and did some measurements. I can at least detect (not enough for anything more)
an incoming signal of about - 115 dbm. 

There is just one oddity - the receiver is always a bit more sensitive beneath the center frequency. As my calibration station is transmitting an AM-signal ( 1khz Audio-SIgnal)
this could also be related to that fact or it could be a filter thing.  I did the BFO calibration earlier, so it should be unrelated to that. But for now that is neclegtable.
It was just strange, that I could hear the signal stronger, if I tuned the SBII a bit lower (higher did nothing).

I also found out what the problem with the MOD-LED was. LED defect, resistance of 18k and no function. :-) As I did not have another red 3mm LED I changed it to yellow.
Now I get some flackering, but it is nearly nothing (even if the MOD poti is tuned fully to the right.. Maybe thats because red LEDs need less voltage than yellow.Minor problem.
I used a second receiver to check modulation and it seems okay.

I also noticed that maximal power in CW is about 5,5-6W. This is a bit less than stated in the manual of the SBII (10W - I think this is for 80 and 40m) and closer to the manual of the SB1 (7-8W),
but I can totally live with that :-)

It really was a lot of fun

Maybe I need a second one for 40m :-)

Re: Should I do another batch of Slop Bucket kits? #poll

ajparent1/kb1gmx
 

No, just barking dogs.

What happens is someone goes on the web version and sees
a topic and not the dates and replies.  That triggers emails
as that how most get it messages, and they start replying.
We then get a cascade about something started 6/2/2018.

Allison

Re: Should I do another batch of Slop Bucket kits? #poll

Dale Lam
 

What has happened to thte postings? It looks like there has been a groups io failure of some kind.
Dale Lam - NoOU

Re: Should I do another batch of Slop Bucket kits? #poll

ajparent1/kb1gmx
 

An aside, recent responses are to a posting over a year old.

Allison

New file uploaded to kd1jvdesigns@groups.io

kd1jvdesigns@groups.io Notification <kd1jvdesigns+notification@...>
 

Hello,

This email message is a notification to let you know that the following files have been uploaded to the Files area of the kd1jvdesigns@groups.io group.

Uploaded By: Steven Weber <steve.kd1jv@...>

Description:
20M LSB bug fix, Freq mem location fix, save SREG in interrupt timer.

Cheers,
The Groups.io Team

Re: SB II #112 nearly done / searching the last building mistakes

Steven Weber
 

Are you building this for 20 meters?

 

I see now I should have specified a smaller value for C67 for a 20M build. A bit too much attenuation for a 23 MHz LO. You could try changing it to 22 pfd or eliminate C67 and replace it with a 1 K resistor to get a consistent level regardless of frequency.

 

If you have not calibrated the oscillator, doing that will make a big difference. Without calibration, the BFO frequency can be off a few 100 Hz or more.

 

On 20M there is no real need for LSB, that option was added so FT8 could be used on 40, which requires USB.

 

Steve KD1JV

 

 

 

 

A quick look at the data sheet for the 74HC4053 shows that it probably is not the culprit. If you have four 10pF capacitors then it might be worthwhile replacing C60-62 and C67 (currently 47pF) with those. My modeling shows a better level balance with an improvement of 10dB on  23 MHz. 73, Don

_._,_._,_