Date   
D4D: Part List Updated with IMD mod and more options

Adam Rong
 

Folks,

See this:
https://groups.io/g/crkits/files/D4D%20Kit%20Documentations/d4dpartlist20190728forMP_80_40_30_20.xls

The changes are marked in blue. The IMD mod becomes easier if you just replace C5 by a 105 monolithic which will be supplied in the latest version kit. You don't have to do more complicated modification as shown in modification 1 in the full manual. Also, I have added both Mini Wire Antenna Kit and 6-60m 100W dipole as the standard options.

Thanks,
Adam

Re: Sound card powerful enough to key D4D VOX?

Trent Trent
 

I've got $1 ebay USB sound cards and they work fine for the VOX,the only problem I have is the radio is deaf and wont go on freq no matter what but atleast the VOX works


On Sun, 28 Jul 2019 at 08:09, Mark Sykes <marksykeskd8rg@...> wrote:
Adam,

Thanks for the info, I ordered the $10 unit. 

Mark

On Sat, Jul 27, 2019 at 5:57 PM Adam Rong <rongxh@...> wrote:
Mark,

The newer generation built-in sound card has to meet an European hearing protection standard EN50332 and the max output voltage will not exceed 150mV on a 32 ohm load. This is the reason why they cannot drive D4D as the VOX circuit requires 600mV. However, we can easily find other USB sound cards, such as the $25 Creative SoundBlaster Play3! and the $10 one I am offering at http://crkits.com in D4D Frequencies and Options drop down menu. The background noise and interference pickup are both very important, and these two are qualified for FT8 operation per our test.

Before you make a purchase, please make sure you have pushed both Pwr and system volume to max. Also, make sure you are controlling the correct sound card. If you find your sound card cannot drive VOX at all or cannot drive constantly, you can consider the sound card purchase.

Thanks,
Adam

Re: D4D: Part List Updated with IMD mod and more options

Trent Trent
 

Are ya sure u mean a 1uF cap?


On Sun, 28 Jul 2019 at 09:57, Adam Rong <rongxh@...> wrote:
Folks,

See this:
https://groups.io/g/crkits/files/D4D%20Kit%20Documentations/d4dpartlist20190728forMP_80_40_30_20.xls

The changes are marked in blue. The IMD mod becomes easier if you just replace C5 by a 105 monolithic which will be supplied in the latest version kit. You don't have to do more complicated modification as shown in modification 1 in the full manual. Also, I have added both Mini Wire Antenna Kit and 6-60m 100W dipole as the standard options.

Thanks,
Adam

Re: D4D: Part List Updated with IMD mod and more options

Adam Rong
 

Yes. It is a 1uF monolithic.

Thanks,
Adam

在 2019年7月28日,下午2:55,Trent Trent <vk7hrs@...> 写道:

Are ya sure u mean a 1uF cap?

On Sun, 28 Jul 2019 at 09:57, Adam Rong <rongxh@...> wrote:
Folks,

See this:
https://groups.io/g/crkits/files/D4D%20Kit%20Documentations/d4dpartlist20190728forMP_80_40_30_20.xls

The changes are marked in blue. The IMD mod becomes easier if you just replace C5 by a 105 monolithic which will be supplied in the latest version kit. You don't have to do more complicated modification as shown in modification 1 in the full manual. Also, I have added both Mini Wire Antenna Kit and 6-60m 100W dipole as the standard options.

Thanks,
Adam

Re: D4D: Part List Updated with IMD mod and more options

Adam Rong
 

Folks,

For the IMD mod, I mean I opted for the new modification method described in Modification Possibilities 5 instead of the first one. it will make life easier since I can supply the 105 monolithic capacitor in the latest kits. I haven't modified the PCB.

Thanks,
Adam

D4D: Why LSB is not that problematic to PSK mode

Adam Rong
 

Folks,

I just read a post from an angry Japanese PSK mode operator:
https://groups.io/g/rttydigital/topic/ft8_by_d4d_dsb_transceiver/32465355?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,32465355

I don't think D4D is that problematic and people don't have to worry too much. The PSK31 decoding capability is about -7dB SNR, so if you use QRPp power level, you will less likely to achieve successful QSO, which means it won't cause effective interference. The problem arises when D4D transmission is nearby to the PSK operator. However, I think people won't use D4D as a daily transceiver for FT8. The most common user scenario is we use it as field operation. Anyway, D4D is a very simple radio and it has unwanted side band and IMD products. If your neighbor hams knock your door, just stop transmission and use it in the field with a portable computer or a raspberry pi instead.

Thanks,
Adam 

Thanks,
Adam

Re: D4D: Accessories Ideas

Adam Rong
 

Folks,

As I have added more options or accessories, here I have to give a simple selection guide for your reference. How to order? Visit http://crkits.com and find the drop down menu for D4D order.

Y audio adapter vs. USB sound card
  • Make sure your computer sound card has enough driving capability before you purchase a Y audio adapter, as D4D VOX circuit needs 600mV signal to activate transmission. 
  • If you are unsure, buy a USB sound card option along and it will save you Y audio adapter as it has separated jacks for headphone and microphone already.

$25 Creative Play 3! or $10 USB sound card
  • Creative Play 3! has about 17 dB range after it triggers the VOX, while the $10 one has about 7 dB. 10 dB more range will give you more flexibility to pursue nice signal or a bit big power. 
  • The background noise is quite clean for both cards, while it seems that $10 USB sound card has a bit more noise pickups at lower frequency range. Most of the time, it won't cause problems for the FT8 QSO.
  • Play 3! is not available for order from http://crkits.com

Mini Wire Antenna Kit vs. 6-60m 100W Coil Dipole
  • If you like to build a tiny antenna by yourself, you can choose the first one. The nice part is that you build a EFHW, Dipole or 9:1 UNUN etc with the kit. The power level is < 15W for SSB, and < 5W for FT8. If you wish to have bigger power, you can consider QRO kit version (take email order now). The added 4 USD will give you < 15W for FT8. You will supply wires for the radiators.
  • If you want a nice looking readily available antenna product, you can choose 6-60m 100W Coil Dipole.
  • These two antennas are not good choices for 80m band or lower. However, they work great for higher bands.

Thanks,
Adam

Re: D4D: Part List Updated with IMD mod and more options

Fernando S
 

Hi Adam!
So just replacing C5 by supplied 105 Will work? No other modification?

Thanks

De: Adam Rong
Enviado: sábado, 27 de julio 20:57
Asunto: [crkits] D4D: Part List Updated with IMD mod and more options
Para: crkits@groups.io


Folks,

See this:
The changes are marked in blue. The IMD mod becomes easier if you just replace C5 by a 105 monolithic which will be supplied in the latest version kit. You don't have to do more complicated modification as shown in modification 1 in the full manual. Also, I have added both Mini Wire Antenna Kit and 6-60m 100W dipole as the standard options.

Thanks,
Adam


Re: D4D: Part List Updated with IMD mod and more options

Adam Rong
 

Correct. This modification is made by BH4DCL and it is smart.

Thanks,
Adam

在 2019年7月29日,上午8:56,Fernando S <fsclavo@...> 写道:

Hi Adam!
So just replacing C5 by supplied 105 Will work? No other modification?

Thanks

De: Adam Rong
Enviado: sábado, 27 de julio 20:57
Asunto: [crkits] D4D: Part List Updated with IMD mod and more options
Folks,

See this:
The changes are marked in blue. The IMD mod becomes easier if you just replace C5 by a 105 monolithic which will be supplied in the latest version kit. You don't have to do more complicated modification as shown in modification 1 in the full manual. Also, I have added both Mini Wire Antenna Kit and 6-60m 100W dipole as the standard options.

Thanks,
Adam



Re: New Record: D4D QSO Distance

Adam Rong
 

BG7IKK did it again! Now with N0FW with distance of 12821km.

Thanks,
Adam

在 2019年7月18日,下午8:13,Adam Rong <rongxh@...> 写道:

Folks,

Still remember the quarterly contest? Last time the 1st place was BG7IKK. He made a QSO from Guangzhou China to Italy with distance over 9000km. Today he refreshed by a QSO with W4UAT with distance of 11233km. He got report of -19dB!

His rig is our D4D 20m and the antenna is an EFHW.

You still have chance to win the contest before the deadline of the end of September. Show us your QSO!

Thanks,
Adam

Re: Preliminary Specifications of 6-60m 100W Coil Dipole Antenna

Charlie Vest
 

I bought this antenna when Adam first announced that it was available . Since I have to depend on my grandson to do my antenna work for me , due to my physical limitations and he was able to easily figure it out and get it in place temporarily , it still isn't where it will end up . It covers just the right bands that I was in need of another antenna for.

I must say the service was very fast and it is a quality product from start to finish !! It is 100 % complete down to a nice bag to carry it in if you plan on using it portable.

VERY well built and I am looking forward to getting it up to its higher permanent location .

Charlie , W5COV

On July 25, 2019 at 10:11 AM Adam Rong <rongxh@...> wrote:

Robert,

You can order now from the drop down menu of D4D order and choose 6-60m Coil Dipole Antenna.

Thanks,
Adam

On Thu, Jul 25, 2019 at 10:09 PM Robert KF6FOD < rgp415@...> wrote:
Where and when can I order this antenna ?



--
Thanks,
Adam Rong

 

D4D mods

Steven Weber
 

The SA602 only requires a 50 mV p-p signal to fully unbalance it. Larger signals create all kinds of unwanted mixer products. Since the VOX requires a 1200 mV p-p signal to trigger it, there needs to be a lot of attenuation between the audio input and the mixer, of about a 25:1 ratio. A 22K/1K divider would be close enough.  

The apparent reduction of power is the result of a cleaner, linear output and the fact that a watt meter reads the average power of the DSB signal.  If nothing else PLEASE MAKE THIS MOD!

The best way to go would be to add a trimmer resistor to the mixer input. Adjust the sound card output level until the board trips into transmit, then turn up the audio level to the mixer with the trimmer until the power output no longer increases. Now back down the level until the power drops off by a little more then 1/2. You are now operating the mixer in it's linear mode and not "flat topping". If you can monitor the output signal with a Scope, this is obvious. 

You can make the VOX more sensitive by adding a resistor from the base of Q5 to ground. A 150K resistor would make the VOX much more sensitive. The idea is to pre-bias the base just below the point at which it starts to turn on, with a little margin for supply voltage and temperature variations. If you do this, then the attenuation to the mixer can be reduced. 

Unequal loads on the outputs of the SA602 will unbalance the mixer and allow carrier to leak through. This happens when Q1 is turned off during transmit. All of a sudden all the current needed for Q1's emitter load is being supplied by the mixer output. To fix this, add a diode between the +5 supply and the collector of Q1 (cathode to Q1). It would probably also help to make R2 and R3 the same value to further balance the mixer output loads, but just adding the diode should be enough. This will significantly reduce or eliminate the carrier.  

You can test if your transmitting a lot of carrier by manually switching the board into transmit by grounding the relay at Q7with no audio input. 

73, Steve KD1JV 

Re: D4D mods

Trent Trent
 

Have u done the mods yet Steve?
Btw have u got a AM BCB filter on yours and is it my mixer or is urs also seem a bit deaf on RX?

On Tue, 30 Jul 2019 at 08:22, Steven Weber <steve.kd1jv@...> wrote:
The SA602 only requires a 50 mV p-p signal to fully unbalance it. Larger signals create all kinds of unwanted mixer products. Since the VOX requires a 1200 mV p-p signal to trigger it, there needs to be a lot of attenuation between the audio input and the mixer, of about a 25:1 ratio. A 22K/1K divider would be close enough.  

The apparent reduction of power is the result of a cleaner, linear output and the fact that a watt meter reads the average power of the DSB signal.  If nothing else PLEASE MAKE THIS MOD!

The best way to go would be to add a trimmer resistor to the mixer input. Adjust the sound card output level until the board trips into transmit, then turn up the audio level to the mixer with the trimmer until the power output no longer increases. Now back down the level until the power drops off by a little more then 1/2. You are now operating the mixer in it's linear mode and not "flat topping". If you can monitor the output signal with a Scope, this is obvious. 

You can make the VOX more sensitive by adding a resistor from the base of Q5 to ground. A 150K resistor would make the VOX much more sensitive. The idea is to pre-bias the base just below the point at which it starts to turn on, with a little margin for supply voltage and temperature variations. If you do this, then the attenuation to the mixer can be reduced. 

Unequal loads on the outputs of the SA602 will unbalance the mixer and allow carrier to leak through. This happens when Q1 is turned off during transmit. All of a sudden all the current needed for Q1's emitter load is being supplied by the mixer output. To fix this, add a diode between the +5 supply and the collector of Q1 (cathode to Q1). It would probably also help to make R2 and R3 the same value to further balance the mixer output loads, but just adding the diode should be enough. This will significantly reduce or eliminate the carrier.  

You can test if your transmitting a lot of carrier by manually switching the board into transmit by grounding the relay at Q7with no audio input. 

73, Steve KD1JV 

Re: D4D mods

Adam Rong
 

Hi Steve,

Thanks for your sharing. I will test them. One thing to confirm: If we add a diode between +5V and the collector of Q1, when 12V_R is present, the diode will be reverse biased? If not, I suppose it will mute the audio output.

Thanks,
Adam

Re: D4D mods

Steven Weber
 

Yes, Q1’s collector should stay above 5V when 12_V is applied.

Steve

 

 

From: Adam Rong
Sent: Tuesday, July 30, 2019 10:33 AM
To: crkits@groups.io
Subject: Re: [crkits] D4D mods

 

Hi Steve,

Thanks for your sharing. I will test them. One thing to confirm: If we add a diode between +5V and the collector of Q1, when 12V_R is present, the diode will be reverse biased? If not, I suppose it will mute the audio output.

Thanks,
Adam

 

Re: D4D mods

Adam Rong
 

Sounds good. I will modify the emitter resistor from 1.5k to 680 ohm and give it a try later this week.

Just FYI: After applying the diode modification to reduce NE602 power supply voltage from 5V to 4.3V suggested by BH4DCL, the carrier leakage is greatly reduced. Maybe your modification will help further.

Thanks,
Adam


On Wed, Jul 31, 2019 at 4:36 AM Steven Weber <steve.kd1jv@...> wrote:

Yes, Q1’s collector should stay above 5V when 12_V is applied.

Steve

 

 

From: Adam Rong
Sent: Tuesday, July 30, 2019 10:33 AM
To: crkits@groups.io
Subject: Re: [crkits] D4D mods

 

Hi Steve,

Thanks for your sharing. I will test them. One thing to confirm: If we add a diode between +5V and the collector of Q1, when 12V_R is present, the diode will be reverse biased? If not, I suppose it will mute the audio output.

Thanks,
Adam

 



--
Thanks,
Adam Rong

Great Kit

samir@...
 

Hello,
I would like to share with you photos and information about the kit that I posted on www.Laselki.net , I made hundreds of QSOs so far with the D4D.
http://www.laselki.net/vb/showthread.php?t=12157

Best 73,
Samir
OD5SK , HZ1SK

Re: Great Kit

 

just a heads up the oven resistor needs to touch the crystal case.

Re: Great Kit

Adam Rong
 

samir,

Nice job on the building and QSO made. You are welcome to join the contest this quarter.

Thanks,
Adam

Re: Great Kit

yves delaforge
 

Many thanks for your information. good luck yves


Le sam. 3 août 2019 à 09:25, Adam Rong <rongxh@...> a écrit :
samir,

Nice job on the building and QSO made. You are welcome to join the contest this quarter.

Thanks,
Adam