QRSS receiver crystal for 10 meters

The 28.188MHz crystal arrived today from Nick, VK1AA. Have been hanging out for it to arrive and would really like to get a receiver up and running.

This weekend looks like being a scorcher, about 38c, so a bit of indoors building will be in order. Which also leads one to think about oscillator stability. With night time temperatures of 15c to day time temperatures of 35+c degrees there is plent of room for drift.

Thoughts on work to do;

• An antenna for 10 meters; vertical or dipole?


• If heading down the di-pole route, balanced or OCFD?


• Maybe a balun?


• A transmission line should be straight forward, I have some spare clean RG-213.


• How about a tuner, then how do I measure if its really working?


• If a vertical, what about a copper cactus or a just a 5/8 vertical?


• Should I make the local oscillator in a separate box?


• If so I could drive the Kenwood to TX test ... wonder what specs are required to drive its VFO port?


• Then modify the 'sudden tunner' style DC receiver. Based on an NE602 and LM386.


• Hook up to peecee with 96KHz sound card.


• Grab with glfer or baudline.


• Announce its ready...


• Later develop something more focused around web based delivery.


• Find a design for a non-computer 'controlled beacon'. A condition of the Foundation Licence.


• Perhaps a beacon controller as simple as a pair of NE555's and a 4017. The first NE555 at a 30 second on/30 second off interval, driving the clock line of the 4017. The first output pin of the 4017 could then drive the second NE555 with a 3 second on/3second off interval. Effectively sending a '5' every ten minutes in QRSS 3 second dots. The '5' being from the call sign of VK5. My call sign being VK5FNET. But thats a job for another time, but would be nice to know what folks think...

So, thoughts on work to be this weekend;

• Get any antenna up


• Get a length of RG-213 terminated with PL259 connectors


• Blow the dust of my 4:1 balun I made some time back and check the connectors out


• Modify the 80m DC RX to run on 10m


• Patch up some audio cable for the DCRx to peecee sound card


• Work out how to capture images or do screen dumps from glfer


• Announce it...

Doesn't sound like much on 'paper', but on top of the domestic chores should be a busy weekend.

72's

Kim - VK5FNET

Progress on NE602 based direct conversion receiver

So today I stayed home due to brain pain, it had been building up for the last few days. Also I had difficulty with my balance. To the point that walking involved bumping into everything. Lots of water and pain killers helped a little, breakfast and coffee later helped a little too. However the head ache didn't wear off until late into the afternoon with more sleep. So I spent some of the day sitting down, tidying the shed.

The cool thing about that was I found a couple of little paper bags with parts that I had bought months back and promptly filed for safe keeping in boxes! Anyhow, that list of parts contained an SA602, 3.579MHz crystals, a variable poly-cap, a large breadboard and some zeners.

This was all the missing parts for the NE602 based direct conversion receiver I've been wanting to build. So late this afternoon I sorted out all the other parts, put them in a box and setup on the kitchen table to assemble. My soldering iron and other tools are currently at a friends, so I pretty much had to assemble everything up on the breadboard.



Made dinner, a tasty curry with shallot pancakes. Then assembled it as per the circuit from W1AW. I am not sure where I first found it, google has a few references to it about. There are also a few variations on the NE602 direct conversion receiver, like the MRX-40_Mini_Receiver and another that I like using LC tank circuits for both the RF input filter and the oscillator side.

I fired it up but heard absolutely nothing. Much comparing with the diagram led to adding the vcc and ground rail for the LM386, after which I could hear familiar hash with the speaker held very close to my ear. I dug out the Pixie2 hoping to create some kind of signal. However the oscillator from the Pixie2 did not create the expected signal or inteference on the DC receiver. So this needs looking at another day when I can focus for more than ten minutes at a time. Hopefully this coming weekend wont involve any more headaches.

Kim VK5FNET