Thursday, January 7, 2021

JH8SST/7 FT8 dc receiver

JH8SST/7 FT8 dc receiver

In one social media one of my friend, living in JAPAN call sign  JH8SST/7 does lots of home brewing. I liked his design skills. His boards are cute, simple & working.  I saw & followed his design steps as he outlined on the twitter and asked one or two questions and he very courteously replied it. I am putting his work for my information and as a collected resource for inspirations for others. I hope my friend JH8SST will like this write-up. All copy right and credit is due to him. I just publish as it is.

Assembling a direct conversion receiver for 3.5MHz FT8 reception.  

The circuit diagram

First of all the circuit diagram. this ckt is based on VK3YE our all time favorite PETER from Australia.

JH8SST/7 DC receiver circuit

Now, i have a look at the pcb design and the text with them as translated from japanese to english by google translators. I will request JH8SST to look over this pages for any correction etc.

3.531 mhz xtal

design

PCB pattern

pcb pattern etched & ready

DC rx and other 28 Mhz SSB rx board etched togather

Hi patterned boards, do you want ferrocloride bath ?


xtal osc stage ready

Ahha finally completed board !!!

See 9v pp3 battery & board in plastic box.

with antenna tuner board is roaring.

another look of the board please.

Computer FT8 screen dump

beautiful japanese balcony with antennas.

QSL CARD.

JS8 & FT8 are slightly different thing. At present i know nothing about the JS8Call but have a look at its American inventor vedio https://youtu.be/G2kv41mVLPk    a 15 minutes vedio.Hope that will give enough information's about what is JS8Call , how to install software into computer, what should be interface between computer and transceivers and also do not forget to see the video of vk3ye channel. http://js8call.com/

Now the text as translated, you can understand  it as a build log.

My note  

Now, i feel that FT8 reception will be achieved by a simple device and that will be inspirational for other to make their own. IMHO The Japanese transistors can  be substituted by any of our locale HF variety or even BC547 will work as used by VK3YE, 2N3819 FET, 1n4148 can be substituted for build. Will i ever try it ? do not know. I need to finish-up my long pending projects, box them up and then think on these digital technology.  

My dear friend JUN did look into the blog and corrected the google's Japanese to English translations. I am thankful for that. Now everything is OK enjoy the wheel.

1 comment:

  1. I agree that using a DC receiver makes sense for FT8. I tried to use a SA602AN IC but didn't like the results. Now I am going to use the circuit you posted and wonder is their have been any changes that would make it work better.

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