Sunday 24 October 2021

My Shack

 Here is a photo of my shack.


Left to right. 

1. A home built GPS clock with TFT display (code on M0IFA.me here)

2. QRP-Labs WSPR 200mW TX for 10MHz (30m).

3. Xiegu G1M SSB/CW four band TCVR

4. ELAD FDM-DUO all mode, all band TCVR

5. Antenna switching unit (four way)

6. Auto ATU, MAT-125E

7. MacBook Air M1 used for Digital with the FDM-DUO, mainly FT8 across the bands

8 An older Macbook (x86) using Apple Bootcamp to run Windows 10 Pro for the SDR software for the ELAD FDM-DUO.

9. On the table a NanoVNA used mainly for tuning my AL-705 loop antenna and checking the SWR

So far so good, all working.


Saturday 16 October 2021

WSPR 30m / 200mW IO92 / M0IFA and antenna update

 My Al-705 loop antenna has the capability of one, two or three loops. I will make a series of tests of WSPR reception on 10MHz (30m) with these options, with a transmit power of 200mW. 

Comparison
Now I am making a careful comparison, it will take 3 weeks! I want to see if the number of loops on my antenna makes a difference. First here is five days with 3 coils.


10MHz 5 days, 3 coils

I each case I have decided not to connect the loop directly to the QRP-Labs 200mW transmitter, but to connect via an ATU. My MAT-125E  auto ATU needs a minimum of 1W TX to tune, and so I have switched to my ELAD FDM-DUO at the same frequency 10,140,200Hz, and output a tuning signal of around 1.3W. Then switch back to the QRP-Labs 200mW output. The FDM-DUO showed an SWR of  1.5:1 on tune (down from 2.6:1 without the ATU. I checked the tuning also with my NanoVNA to see the SWR minimum at the correct frequency.


10MHz 5days , 2 coils

There is practically no difference between 3 and 2 coils on the loop antenna. May be just a little lower S/N ratio and fewer spots. 

Seems there is little difference between ,3 2 or 1 coil. Here's the one coil data


10MHz 5days , 1 coil

But more interesting might be any correlation, as you might expect, between sun spot numbers and the results. For example, the last day of one coil above shows a very poor day for 10MHz propagation. And sure enough the SN was a low 31. 

A fast way to check the propagation is a new app from N0NBH called "Solar". This runs on the iPhone but also on the new MacBook Air M1. Here is todays info:



SUN
And if you want the latest picture of the sun click here





Friday 8 October 2021

Club QO-100 transmitter

An uplink converter (here) for transmitting to the QC-100 satellite has been built by numerous amateurs


This is the layout with individual "ebay`' items fixed to a mounting board, interconnected by SMA cables.

The Banbury Amateur Radio Society is building one of these along with the TX/RX antenna and LNB. So far we have connected up the units free across the table, and are feeding it a 432MHz input at up to 10W through a 20dB attenuator. Awaiting PSU module for +8 and +5V. No results yet, but will document as the project goes ahead.

So here's the project going ahead - it is NOT a shambles, promise

Some of the modules scattered around

And proposed box which will go outside near the dish

Just a couple of new photos as we have a club presentation about the Ofcom EMF checking we all have to do: spreadsheets and all that. I think I am exempt with max 5W TX and indoor loop antenna! Or also with my 200mW WSPR TX.

The task goes on... the antenna is proving difficult to bild as the plates keep warping when heated to solder them, tried twice so far but still a problem. This is the state of play, I'm sure something will rise out of the jungle...

We have a receiver going with a commercial LNB and dish, but it drifts quite a lot and we must xtal stabilise it. We are using an SDRplay with SDRUno software to tune to the LNB output on 739MHz.

Update: the main components are mounted on the board and we have an output at 2.4GHz from a transceiver and 20dB attenuator at 430MHz. Now to add the filters and power amplifier.


So this is what it now looks like, but building has stopped as one of the power supplies blew up and we are waiting for a replacement.

RX

There is talk of moving to an RTL dongle and I would like us to try GQRX software... as it runs on the Mac!!!

QO-100 frequencies

The tuning and TXRX frequencies are