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 pskreporter.info 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 pskreporter.info

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 pskreporter.info

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

2m Sporadic E 2019/07/02

Today i managed to catch a tiny bit of the 2m sporadic E opening. Although i only have a tiny setup with 50W into a mobile antenna on the rooftop i was able to work 3 stations in soutch EA. The cloud was above HB9 and gave some good signals from EA.
I worked:
This was how the MUF map from dxmaps.com did look like:

2m sporadic E map (dxmaps) 20190702

And in those locations i was heard during the evening:

pskreporter dh5ym coverage 20190702

Posted in VHF

Octagon OSLO TCXO Modification

I have an older OSLO LNB which, was my spare for the websdr. Now i want to use it for QO-100. To improve the temperature stability a TCXO was fitted in place of the original crystal. Find some pictures below.

The type is a TXC 7N-26.000MBP-T from TXC. It works from 2.7 to 5.5V. Luckily the LNB works with 5V from an 7805 regulator. The TCXO was supplied by Michael DG0OPK. He suggested this type and already modified a OTLSO some years ago.


Some warning: This might not apply to current types of the Octagon LNBs. As far as i know you will likely get a 25MHz crystal version if you try to buy one. It will not be possible to use the 25MHz LNB with a lower reference frequency.

LNB with NXP TFF1017 IC could be an alternative as far as i know. I have no experience with this type. Here is some reference:


Back to the OSLO:


First i removed the crystal. It is necessary to use hot air because otherwise the pads might be damaged. But they are still needed. Also the 0 Ohm resistor over the two traces that go between the two pads needs to be removed. The trace connected to the former crystal pad closer to the RF section needs to be disconnected. This crystal input will be left unconnected.

OSLO LNB with crystal removed

Now a insulated copper wire can be connected to the pad of the former 0 ohm resistor that leads to the converter IC. The capacitor to ground at the crystal pad close to the 7805 regulator needs to be replaced by a short. The other crystal capacitor should be replaced by 100nF.

OSLO prepared for mounting TCXO

Now the TCXO can be soldered. It is important to avoid shorts of the pins of the TCXO towards the PCB. I soldered the TCXO slightly elevated. It is important to keep distance from the border of the PCB because the cap of the LNB still needs to be mounted. The insulated copper wire can be connected to the output of the oscillator which is pin 5 (right of the row of capacitors). The pad with the remaining capacitor towards ground needs to be connected to the output of the 5V regulator. It is the regulator pin with the 0 ohm resistor.

The pins of the TCXO are assigned as: 9=VCC (left of the capacitors), 4=GND, 5=Output.

OSLO with TCXO mounted