Some QO-100 trials

This weekend i did some new trials with QO-100. In the picture you can see parts of setup i used. This time the TX setup was purely classic. You can see it in the grey box in the foto below. FT-817 on 2m as IF followed by an upconverter made from some old UMTS measurement equipment block (silver box in the middle). It does dual upconversion with high-side LO. The LO consist of an ADF4351 each (the two smaller boards above the converter). The reference is a 96MHz OCXO of G8ACE design (left of the PLL boards). The converter block generates up to 200mW on 2.4GHz. I drive a WLAN PA (black box) that probably generates 1W. And the final PA is a MRF21030 PA (on the big heat sink on the right). It provides about 10W in SSB. The antenna is my 60cm offset dish with the DJ7GP patch (the one that has the round patch element). Left to the grey TX dish you can see a black 40cm camping dish with Octagon LNB and TCXO modification. But instead i used the BATC websdr this time. The reason is the amount of cable i currently have. I use 3 power supplies (28V, 13.8V, 5V). Reducing the number of required cables is one of the next steps. However i was pleased to do some nice QSO.

QO-100 setup

Modification of chinese 6cm PA

Since quite some while there are 5.7GHz PAs intended for video transmission from drones to ground. Those PA are made with 5GHz WLAN IC and very cheap (below 30Euro including shippment). These PA can be used for 6cm amateur radion but need some modification upfront to generate a usable amplifier.

PA6cm 2.5W top side view

The PA comes with heatsink, small fan and a short power cable.

PA6cm 2.5W bottom side view and technical info

The PCB side has a metal cover that has a sticker with some technical data. The PA is supplied with 12-16V. It is intended for 5.7GHz operation. The sticker also mentions 2.4GHz but the PA will not work there. The specified output power is 2.5..3W although the vendors usually state 5W. You will not reach 5W.

PA6cm 2.5W with metal cap removed

Removing the metal cover shows that the PA PCB contains two Sige 5004L WLAN amplifier IC, some splitter/combiner, an input attenuator and a power supply circuit. The connectors are Reverse SMA (RSMA) and they are mounted really poor. I would not even try to use the PA with those connectors and the air gaps to the PCB.

PA6cm 2.5W RSMA connectors removed

Now the silly RSMA connectors are removed. The pads need to be cleaned. Also clean the ground ring to prepare re-assembly of the shield later on.

PA6cm 2.5W with new SMA jacks soldered

Solder some new SMA connectors. The grounds of the SMA connectors shall touch the top side of the PCB. You need to shorten the ground connectors a little bit. Likely you do not have connectors intended for the PCB thickness. You may solder the other side for mechanical reason. Solder the inner pin of the SMA last in order to prevent breaking the RF trace.

PA6cm 2.5W PCB removed from heat sink – no thermal paste

Some attention needs to be put on the thermal conductivity between PCB and heat sink. Removing the PCB from the heat sink shows that cost optimizations safed the thermal compount which makes the heat sink almost useless. So add some thermal paste to the marked areas below the amplifier IC. Probably the switcher IC needs some cooling as well.

PA6cm 2.5W location of input attenuator

The PA PCB contains a input attenuator. The default attenuation is around 18 to 20dB. If you have less input power you might want to change it. For my measurements i removed the 3 resistors and soldered a 0-Ohm upside down to the middle resistor position. After everything is modified and tested you will likely want to re-assemble the metal shield.

The PA has about 27-28dB gain and my sample achieves 3W output at 7dBm (5mW) input and a current of 1.3A at 12V. Saturation might be somewhere at 4W with 10mW of drive and 1.5A current.

Input/Output power [dBm] and gain [dB] after all modifications of the 6cm PA

June 20 Microwave contest

I was working the contest from home and part time. The 23cm transverter with 10m IF and the HiQSDR work pretty well. I used the Quados4 antenna since the 36ele ordered was still stuck in customs. ODX was HA5KDQ and in total 41QSO and 6900 points raw score. I also made some QSO on the higher bands on request. 3x 9cm, 1x 6 and 3cm each.

23cm map of reached contacts by dh5ym during microwave contest june 2020

4m 2020/June/01

After missing the big 2m ES last friday i had some luck on 4m today. Among others i worked GM4VVX, EA6FB, OH1KH, PA3FMP, GW8ASA, GU6EFB, EI8IQ and OY1OF.

reception reports on for 4m on June 1st 2020 for DH5YM. map by openstreetmap contributors.

6/4/2m ES 20.5.2020

Today there was some good ES on the VHF bands. I managed to do some QSO. The FT8 monitor received quite an amount of stations. MUF moved >200MHz and there were some spots of stations from EA/CT… I did not receive anything on 2m.

4m FT8 traffic received by DH5YM FT8 monitor 2020/05/20. Map data by Openstreetmap contributors and waypoint data by

worked stations: EA6XQ, EA3WD, EA5DF, EA6SX, OK1AGE, DL6AKK, CT1BXT, EA5TT

There was some SSB traffic as well. I did not have time to try. Some SSB stations call above .200 and cannot be answered anyway by DL stations.

6m FT8 traffic received by DH5YM FT8 monitor 2020/05/20. Map data by Openstreetmap contributors and waypoint data by

New 23cm transverter and DUR contest

Last weekend i tried to put my new 23cm transverter with 28MHz IF and the 100W PE1RKI PA together. The picture shows my ugly “transverter in a box” construction.

23cm transverter ugly test construction

I used this setup in the March 23cm DUR contest. My ODX was HA5YA via aircraft scatter about 550km distance. I also worked DL3IAE and OM5CM, both >400km.

Newyear tropo

Last days we have strong tropo conditions. Currently i run a Openwebrx with FT8 monitor on 2m and although i only use a small vertical monopole the maximum distance of reports are >800km. Some 2m FM relais from Hamburg was audible very loud. The 70cm band was full of repeaters (i think most of the signals were DMR). This evening i gave 70cm a try. I was surprised to hear LA1UHG beacon from JO59FB (>900km). Other beacons heard: DB0VC (JO45), OZ7IGY, OZ5SHF, DM0UB. I worked SM7LCD in JO86 over 600km with only 30W and Quados-6 antenna.

Below you find a recording of the LA1UHG beacon:

Tropo January 1st 2020.
2m FT8 RX reports for Tropo on January 1st 2020

FM ATV and other activities

Over the past months there was quite some activity here and there but i found no time to document it. For vacation i took my FT-857 and the small duoband yagi and tried some FT8 in the evenings. I also tried some meteor scatter on 2m here and there. In November i found some time to participate in the Marconi contest with the DM7A team from JO60OM which resulted in a 3rd place in DL as multi-Op station. Some small activity was to collect some equipment for watching the local analog TV repeater which was reactivated during the year. After months of searching i found a nice portable FM satellite receiver. The repeater transmits on 10200MHz. With a normal satellite LNB with 9750MHz LO this will be far outside the tunable IF of the receiver. From previous experiments i had some cheap PLL LNB with 25MHz crystal. From previous experiments i found that it was not that usable for narrow band QO-100 acitivities as the 27MHz referenced Octagon LNBs but i knew that the PLL locked down to a 23.3MHz reference. So i ordered some 23.70625MHz crystals and exchanged it. With this crystal 10200MHz is converted to about 950MHz which is just at the lower end of the sat-IF range (the receiver tunes down to 900MHz). From the roof window i can now receive the DB0TUD ATV repeater 10GHz output. I do not know the frequency response of the LNB yet. Most probably the LNB is not very sensitive since the frequency is quite low compared to the satellite band. For some reason i broke my old DVB receivers AV input. So i used a cheap USB video grabber card to watch the video.

Video signal from DB0TUD from the sat-RX output shown on the scope
DB0TUD test picture shown on notebook screen via video grabber
tiny portable dish with modified PLL LNB (23.70625MHz crystal instead of 25MHz)

VUS Contest July 2019

Originally i planned to join some contest operation on the hill. On short notice i had to withdraw because my time did not allow. So i used some time in the night (when the kids are sleeping) and a little time Sunday noon to make some QSO from home. This time i operated a DK7ZB dual band yagi for 2m and 70cm. It is a 4ele on 2m and a 5ele on 70cm. The next highlight was that i was able to turn the antenna automatically and completely do remote operation from anywhere in the flat (at least for 2m). Many thanks to the guys from IQ5NN which where so patient to complete the ODX QSO with my tiny 50W. I also heard IO2V and another I station but was not able to do the QSO. In the end it was 37QSO and almost 10k points of cherry picking. 10 QSO on 70cm were done with the 20W from my good old FT-857D. 23cm i did not plan to do but the antenna was still on screwed to the mast, so i did 5 QSO. One fast local QSO on 13cm finally. 9, 6 and 3 cm were not activated because of no time.

I have to say that i cannot install fixed antennas. So its always a portable like style with small antennas that fit through the roof window or just point out there. And this kind of operation is only possible if it does not rain and it is not too cold.

DK7ZB Yagi for 2/70 and Quados for 23cm