CQ WW RTTY 2015 SOSB-20 

   Again, after a year there is the biggest evenent for RTTY funs :) I wanted to run 80m but did not have a time to have all ready... 4SQ sloper system is waiting for new hybrid, no beverages and so on.

   We spent some time with 20m antennas and have new "BIG" stack of pair HB9CV. I also needed to test new black boxes from our RemoteQTH.com: Multibeaming controller and Stack controller (Open Stack boxes). Than finally I have three antennas systems:

- 5 over 5 at 15/31m

- 2el HB9CV to EA+SA and 2el HB9CV to I and AF at 18m / 10m

- single 5el at 32m

   This works great and helps a lot! See the video down. I could control HB9CVs too, so I could RX just for PY or EA stations or only to AF - this helped to ketch SU9IG and some LU and PY were not be able to copy without this possibility.

  Another big thing - IC-7800. First time I used SO2V and it is great! Also in connect together with big LCD and waterfall. I used dual watch function a lot. It was easy to find some mults than (EA6, TG9 etc).

  And the conditions... I am beginner on 20m band so I do not know it a lot. The Saturday morning conditions brought some VK and ZL LP QSOs but the afternoon, it was fantastic experience! I run as the "zipper" :) Switched between the stack and single 5 el and work NA / JA / NA / JA and what more CA / JA / CA /JA :) Btw the most worked state is CA! 49 QSOs. Than IL 31 QSOs... 

Overall I made 712 NA stations (K + VE), 7 KH6, 5 KL7... And 263 JA stations.

   During the Sunday conditions seemd little worse or maybe there ware nobody to work? :) Rates went down. The best hour rate was 88 QSOs. 

 

10m H-frame stack - 20m systems:

Multibeaming example:

QSOs     Pts  ZN    Cty   SP
1937    5018   36  107   57

Score : 1 003 600

Thanks a lot to all and hope to meet you soon on RTTY and next in CW WW SSB!

RX ANT Switching box,    part 2 - Preamp IP3

   There is my next blog post. It is focused to the IP and gain measurements of the single and double preamplifier. I use Motorola 2N5109 transistors and classic W7IUV design. As I described in my previous post , there are two splitted ones.

   

   I can switch off stage by the jumpers and sets bias for each transistor. It the table, you can see what happenes for the different biases and voltages. I measured output P1dB point (OP1d) and than calculated output IP3 (OIP3) :

 OIP3 = OP1d + 12  [dBm; dBm, dB]

   All measurements are done at 3500 kHz. I used R&S FSH6 + ATT + amp + ATT.

  You can see that double preamp IP3 is almost by 3dB better than the single transistor one. This responds the theory... Do not forget that there should be +- 1dB mistake :-) And IP3 is just calculated, not measured by 2-tone generator! But anyway you can obtain UFB results with this design. Do not forget, this preamp can easily exceedes 27 dBm (500mW) of the output power! This is quite a lot for the "normal" receiver :-)

RX ANT Switching box,    part 1 - BPF

   It is a few years when I want to re-designing the RX antennas switching for Multi-Multi with two independant RX per band. There is our idea: 

High IP preamps in the feed point of each beverage --- long coax --- RX ant switching box

And RX ant switching box design:

Input connector (per ant) --- triband splitter --- two way splitter per band --- switch 1 of X (per RX) --- BPF + notch + ATT + preamp + ATT + diplexer + (high power TX protection)

So this article is about Singleband RX pream board:

PCB and schematic:

   The design: at the input, there is BPF. I have found really nice design from PA3AKE, please have a look at his full project! It is really nice piece of HW! There I added noth filters. I can easyly have stop band over 60dB! So this is the BPF design, than there is ATT, which you can switch ON and OFF and independant switching for preamp. In this case, preamp is done by splitting two W7IUW ones. By this you can obtain higher IP3 - see next post :-) Pream is loaded with 3dB ATT and diplexer.

And there are BPF measurings:

160m:

80m:

40m:

Full preamp ON (G=16dB):