my d4d is off frequency, low by 2khz . do i decrease or increase capitance. it's at 14.272.
thanks, ron
kc0tdj
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What diode is recommended for Steve's Mod?
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Re: dB level and TX timings
Hi Conor EI6GSB,
Thanks for reporting this. I have never met this before. If you have spare part, you can try to swap NE602 to see if it is better. Also, check if you have properly attach the final transistor to the rear cover to help heat sink.
Thanks,
Adam
Thanks,
Adam
Hi all again,
After some more investigation I believe this simply may be a case of the transceiver overheating. I opened the case to inspect the board to see if there were any signs of component damage, and everything looked fine. I powered up the transceiver and I still experienced the original problem, but after a few minutes the TX timings returned to normal and the dB level dropped down to about 23dB.
My radio shack got very warm over the last couple of days (over 30 degrees C) and I while troubleshooting I opened the door to let the room cool down for my own personal comfort. I think that this, combined with the black, heat-absorbing enclosure of the transceiver caused the components on the board to overheat and not function correctly.
Thanks to the nature of the enclosure and the board, the D4D transceiver may lend itself to a cooling system modification for people operating in unusually warm climates.
Thank you, too, to Adam for developing the kit: it was fun to assemble and I'm looking forward to making some QRP contacts!
73,
Conor EI6GSB
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Re: dB level and TX timings
Hi all again,
After some more investigation I believe this simply may be a case of the transceiver overheating. I opened the case to inspect the board to see if there were any signs of component damage, and everything looked fine. I powered up the transceiver and I still experienced the original problem, but after a few minutes the TX timings returned to normal and the dB level dropped down to about 23dB.
My radio shack got very warm over the last couple of days (over 30 degrees C) and I while troubleshooting I opened the door to let the room cool down for my own personal comfort. I think that this, combined with the black, heat-absorbing enclosure of the transceiver caused the components on the board to overheat and not function correctly.
Thanks to the nature of the enclosure and the board, the D4D transceiver may lend itself to a cooling system modification for people operating in unusually warm climates.
Thank you, too, to Adam for developing the kit: it was fun to assemble and I'm looking forward to making some QRP contacts!
73,
Conor EI6GSB
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Modification is not necessary if you want to get it work first. After you have time, you can consider these two modifications:
1. Replace C5 by a 105 monolithic cap (tolerance < 20%) to improve IMD at the cost of half RF power at the same audio input.
2. Add a diode per KD1JV to improve carrier leakage.
If your sound card output is too low to drive VOX, consider KD1JV improvement to add a 150k resistor. This mod will not become standard as it is related with transistor parameter and power supply voltage. You make your call to modify it or buy a USB sound card along.
Thanks, Adam
On Mon, Aug 5, 2019 at 12:29 AM Bryan Brauer < bryan@...> wrote: I just received my d4d kit this week, and wish to incorporate all recommended mods.? Will there be a file that lists all mods, or an update to the instructions that includes all? Bryan B. Brauer, PEConsulting Engineer
On Sun, Aug 4, 2019 at 8:21 AM Adam Rong < rongxh@...> wrote: Steve,
Thanks for reminding. We studied the spec while we apply the 4.3V power supply. The main impact parameters are:
Conversion gain, Noise figure, and IP3i
I believe the major impact is IP3i which will cause worse BCI.
With your modificaiton, I think it is okay not to add BH4DCL diode mod to avoid the impact to the receiver performance. The carrier leakage is now about 10 dB under USB and LSB signals even I applied 10 dB attenuation to the audio input.
Thanks,
Adam
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I just received my d4d kit this week, and wish to incorporate all recommended mods.? Will there be a file that lists all mods, or an update to the instructions that includes all? Bryan B. Brauer, PEConsulting Engineer
On Sun, Aug 4, 2019 at 8:21 AM Adam Rong < rongxh@...> wrote: Steve,
Thanks for reminding. We studied the spec while we apply the 4.3V power supply. The main impact parameters are:
Conversion gain, Noise figure, and IP3i
I believe the major impact is IP3i which will cause worse BCI.
With your modificaiton, I think it is okay not to add BH4DCL diode mod to avoid the impact to the receiver performance. The carrier leakage is now about 10 dB under USB and LSB signals even I applied 10 dB attenuation to the audio input.
Thanks,
Adam
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Steve,
Thanks for reminding. We studied the spec while we apply the 4.3V power supply. The main impact parameters are:
Conversion gain, Noise figure, and IP3i
I believe the major impact is IP3i which will cause worse BCI.
With your modificaiton, I think it is okay not to add BH4DCL diode mod to avoid the impact to the receiver performance. The carrier leakage is now about 10 dB under USB and LSB signals even I applied 10 dB attenuation to the audio input.
Thanks,
Adam
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I would remove the diode in series with the 5V to the SA602. The minimum operating voltage for the SA602 is 4.5V and performance degrades quickly below 4.5V. ? ? Thank you, Steve. Your diode mod is effective. In my test, the carrier leakage improved by about 5 dB, as a side?effect, both USB and LSB signals increased about 1 dB which is a surprise to me. I also applied the BH4DCL diode mod, and it improved the carrier leakage further for another 3 dB, and there was no noticeable difference on the USB and LSB signal level. I did try to change the emitter resistor from 1.5k to half and it won't help too much, so I will not change it. So, my recommendation is that we apply both diode mods, hihi. Thanks, Adam ?
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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 ? ? ? 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
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And the photo follows. The left side is the KD1JV diode mod, and the right side is the BH4DCL diode mod.
On Sun, Aug 4, 2019 at 10:59 PM Adam Rong via Groups.Io <rongxh= [email protected]> wrote: Thank you, Steve. Your diode mod is effective. In my test, the carrier leakage improved by about 5 dB, as a side?effect, both USB and LSB signals increased about 1 dB which is a surprise to me. I also applied the BH4DCL diode mod, and it improved the carrier leakage further for another 3 dB, and there was no noticeable difference on the USB and LSB signal level.
I did try to change the emitter resistor from 1.5k to half and it won't help too much, so I will not change it. So, my recommendation is that we apply both diode mods, hihi.
Thanks, Adam
Yes, Q1¡¯s collector should stay above 5V when 12_V is applied. Steve ? ? ? 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
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Thank you, Steve. Your diode mod is effective. In my test, the carrier leakage improved by about 5 dB, as a side?effect, both USB and LSB signals increased about 1 dB which is a surprise to me. I also applied the BH4DCL diode mod, and it improved the carrier leakage further for another 3 dB, and there was no noticeable difference on the USB and LSB signal level.
I did try to change the emitter resistor from 1.5k to half and it won't help too much, so I will not change it. So, my recommendation is that we apply both diode mods, hihi.
Thanks, Adam
Yes, Q1¡¯s collector should stay above 5V when 12_V is applied. Steve ? ? ? 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
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Hi all, I built the D4D kit a couple of days ago and it worked well. I didn't make any QSOs just yet, but the band conditions are not good so this isn't a problem. Yesterday, however, I powered up the transceiver and I noticed some issues. You will see in my screenshot that the received power level is at 54dB. Previously it was at about 23dB, and I was able to receive a lot of FT8 transmissions. Secondly, you will see that the transmission times start one second later than they are supposed to. Previously they were transmitting at :00, :15, etc. without any problems. This happens in both versions 2.0 and 2.1 of WSJT-X. I also noticed that the transmission duration seems shorter than it previously was, maybe lasting about 11 seconds. Both of these problems began yesterday. At one point I turned on the power to the transceiver and it did not power up: neither the RX or TX lights went on. After a couple of attempts, the device powered up. Occassionally, WSJT-X throws an error about input audio not being found. Has anyone else every had any of these problems, or know how I might be able to troubleshoot? Regards, Conor EI6GSB 
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Folks,
I have decided to join Japan Ham Fair 2019 this year. It will be a fast in fast out trip but I should be able to stay at QRP village booth for about 1 day from August 31 noon to September 1 noon. I have also registered for the QRPer beer party on August 31. I wish to make an eyeball QSO with you guys if you are also going to Tokyo.
Thanks,
Adam
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Folks,
I will be on vacation from August 6 to 11. I will reserve something at my shipping agent, but likely will not be able to cover all your need. The next shipping will be August 19. I still take orders.
Thanks,
Adam
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Many thanks for your information. good luck yves
Le?sam. 3 ao?t 2019 ¨¤?09:25, Adam Rong < rongxh@...> a ¨¦crit?: samir,
Nice job on the building and QSO made. You are welcome to join the contest this quarter.
Thanks,
Adam
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samir,
Nice job on the building and QSO made. You are welcome to join the contest this quarter.
Thanks,
Adam
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just a heads up the oven resistor needs to touch the crystal case.
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Hello, I would like to share with you photos and information about the kit that I posted on , I made hundreds of QSOs so far with the D4D.    Best 73, Samir OD5SK , HZ1SK
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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
Yes, Q1¡¯s collector should stay above 5V when 12_V is applied. Steve ? ? ? 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
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Yes, Q1¡¯s collector should stay above 5V when 12_V is applied. Steve ? ?
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From: Adam RongSent: Tuesday, July 30, 2019 10:33 AM To: [email protected]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
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OD5SK
