Wednesday, 28 October 2015

Magnetic loop antenna

I have been trying out a number of magnetic loop antennas recently and came up with this for use with my Braun T1000 receiver. Both the loop and the coupling loop are made from scrap heliax cabling and the tuning capacitor is from a broken down tube receiver. Now to look for a suitable variable capacitor so that it can be used for QRP transmit as well. More to come .....


Friday, 13 March 2015

CAT cable for Yaesu FT1000D & FT857D (& FT990)

I had a need to control either the FT1000D or FT857D for WSPR/WJST and here is what I came up with, simple and cheap. All my laptops and desktop computers do not have any serial port, only USB's. I have a couple of USB to TTL Serial Converters using the  CP2102 chipset on hand purchased on eBay for about $2.00 shipped and I used one of them for this.

CAT cable

USB to TTL Serial Converter

The above photo shows the cable for the FT1000D which uses a 6 pin DIN connector. Another similar cable was made up using an 8 pin mini DIN connector for the FT857D. Now I can also operate WSPR with frequency hopping using my FT1000D and Ft857D! 

USB to serial converter                                Transceiver CAT connector
                                                                       FT1000(D)      FT857D

RXD                                                               2                      4                                                             
TXD                                                               3                      5 
Gnd                                                                1                      2

If it does not work for the FT1000D install a pull down resistor of 1K5 between pin 2 and ground (pin 1). Yaesu radios including the FT-990, FT-1000D with TTL CAT ports use an 
emitter follower with a high impedance as driver on the serial out line.  With the USB to TTL CP2102 converter, the emitter follower does not provide enough load to pull the input of the
buffer/converter low (< 0.5 volt) in the off state. Yaesu added a 1K5 resistor from pin 2 to
ground in later production of the FT-990, FT-1000D and other radios using a similar circuit. This interface should work on the the FT990 as well.

The USB to TTL CP2102 serial converters are available on eBay or from:
http://www.ebay.com/itm/SY-Hot-Selling-USB-2-0-to-TTL-UART-6PIN-Module-Serial-Converter-CP2102-STC-PRGMR-/271424128315?

Install relevant drivers for the OS you are using from:
https://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx

More to come ....

Wednesday, 11 February 2015

Mac Pro and IBM T221 3840x2400 4K 22" monitor

New addition to the shack Apple Mac Pro and IBM T221 monitor. Managed to get the T221 monitor for 3840 x 2400 display with the Lenovo T510. Still working on the Mac Pro, more to come ........

Apple Mac Pro


IBM T221 3840x2400 4K 22" monitor


3840 x 2400 resolution!