September | 2017 | Rauschfunk

Some posts ago i wrote about my new 6cm transverter. I already did a few QSO and i got a 10W PA for a good price. Unfortunately this PA needs 1W of Input and the transverter gives maximum of 250mW output. So a small “driver” is needed. I was researching the options but found no easy solution that also fits my budget constraints. Then i saw some amplifiers sold as WLAN amp. Usually those are for 2.4GHz but i thought if there are some for the one band there are probably also some for the 5GHz band. During the search i found the nice Amp on the picture below that is sold as an amplifier for video transmissions for about 22Euro. It is specified with 3.5/4.5W. But whatever output power for the price i thought i cannot do wrong a lot.

A chinese 5.8GHz PA

When the device arrived i had to find out the supply voltage. In fact it works with 12V and a first test confirmed it has some gain. The bad thing was that the connectors were reverse SMA and for each connector it was quite some gap between the connector and the PCB. So i thought, “thats a strange matching method” ;)
After removing the soldered shield on top of the PCB one of the screws for mounting the heatsink also came out.
The semiconductors used in the PA are 2x Skyworks SE5004L with a P1dB of 30dBm typical and 34dBm max. So i thought 2W should be possible at least. The gain is specified with 32dB. At the input of the PA is a pi-attenuator.
Later i soldered some nice SMA jacks and then the PA went to storage for quite some while.

The “inner values” of the small amplifier

Now i found some minutes to remove the attenuator and do some raw measurement of the output power. The gain of the amplifier is about 28..29dB. I did not measure the cable attenuation exactly so do not nail me down on the last dB.
The input vs output figure you can find below. The P1dB is about 2.5W. So considering the samples to be typical there is quite some loss on the PCB. But even in that case for the given price its a nice thing.

5.8GHz video PA output power

Yesterday the 4m TX permission in DL ended for this year. Hopefully we get another one next year. For me it was the first time and it was rather interesting to compare real band opening with the propagation prediction on dxmaps. Unfortunately i missed the big ES in June. I was on vacation and also my transverter was not ready that time. But still i made some QSO.
A frequent “beacon” on the band was DK2EA. We had several short qso and it was always a stable connection although we both used low power and small antennas.
During the ES openings i worked EA, EI, SV and LZ. I also worked some OK stations and some local stations as well.

While i was using my FT-817 as IF TRX last days i hooked up my HiQSDR to the transverter.
The day before yesterday i noticed some band opening to G. I heard the beacons GB3ANG and GM8RBR. You can see the screenshot below. While GB3ANG was rather stable over a long time GM8RBR more in the north was fading in and out all the time.