Monthly Archives: July 2017

Almost a antenna feed for 6cm …

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Not all things work out… I was searching for some nice feed for a offset dish to be used for 6cm narrow band. In the internet i found a nice version from Russia.
It was announced for the 5GHz WLAN band without dedicated specification of the exact frequency.
For 40 Euro including shipment it was ordered and after only 2 weeks in transit (russian saying tells: For bad children Santa Claus sends the gifts by russian post… ;) ) and 1 week in customs i finally got my russian present.

5GHz horn from Russia


Measuring the input matching shows that its well in the middle of the lowest 5GHz WLAN band.

WLAN horn matching measurement


Far away from 5760MHz. But ok, lets try. First i removed the N connector.

5GHz horn from Russia


The connector with the radiator seems to be a robust construction. I tried to shorten it step by step. Unfortunately it happened what could be expected. The feed can be de-tuned to about 5.5GHz but above that the matching vanishes. Probably the distance to the backside of the horn is too big. So this one was a fail. Fortunately i can still use it for WLAN if i make the radiator a bit longer again. If you want to use the lowest of the 5GHz bands it is really a nice and very solid construction.

MD380 DMR radio

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I have a Tytera MD380 DMR transceiver now. Flashed latest MD380tools and database yesterday and hope to make a first qso soon. A mmdvm hotspot is in the pipeline but i still need to connect a transceiver.

TYT MD380 DMR radio

Wideband amplifier

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I tested my new assembled wideband high IP amplifier (BX-088) from Funkamateur. The transformers need to be handmade which is a very fiddling task. The cores are really small. I choose for 11dB gain assembly. The measurement shows, that the gain really rapidly drops below the 160m band. The figure fits to what is shown in the documentation. So far i did not measure the p1dB or IM3 behavior.
The points that are interesting for me are 28MHz as LNA for my SDR or as IF amplifier for transverter input on 14/28MHz and usage as pre-amp for 70MHz.

Measurement of Funkamateur wideband amplifier

My first QSO on 4m

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Now finally i have my 4m rig ready. It consists of a DF2FQ transverter with some modification to power module mounting and RX amplifier stage.
Currently i use my FT-817 to drive it. I also added a separate drive input which i need for the SDR. With 1mW input on 29MHz it can achieve about 25W output on 70MHz.
So far i did not benefit from ES conditions. Seems it missed all the nice propagation from last weeks. Hopefully there will be another opening until end of August, when the permission ends here.
As antenna i use a Hentenna Quad with direct 50Ohm assymetric feed point. The antenna has some significant Null in the radiation pattern but is a good compomise for the fibre mast at the balcony.
My fist contact was with DK2EA in JO50UF in CW. Meanwhile i also worked DD1VD and DL2VPO locally.

4m band rig on the balcony

4m Hentenna Quad

[Edit 2017/07/23] meanwhile i worked EA1BFZ in IN81SS and today SV2JAO in KN10DN. ES propagation seems to be very short and spotty. You really need to look to the cluster and search the frequencies all the time. 5 minutes later all could be gone. 100km away the conditions can be significantly different.