July 21 VUS contest

During the time i was qrv i experienced very low participation from DL. Activity from OK was quite good. Some nice AP scatter QSO arranged via ON4KST chat but also random QSO. The SDR really helps to find the people when turning the antenna. Average of 270km/QSO on 70cm and 220km/QSO on 23cm are quite ok for me for operating from home.

Saturday evening 70cm. Rig HiQSDR+Iceni Transverter, 50W, 15ele.
27 QSO 7300p, ODX S59DGO, 610km.

70cm 21/07 – Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA), DL4MFM log analyzer


Sunday afternoon 23cm during the last 2h of the contest.
Rig HiQSDR+MKU13G3, 100W, 36ele.
25 QSO 5500p, ODX S50G, 560km.

23cm 21/07 – Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA), DL4MFM log analyzer

And i almost forgot: 1 QSO on 3cm with OK2A ;) Rig: FT790R2, Transverter, 10W, 40cm offset dish and W1GHZ feed.

IARU June contest 2021

Because of some Covid restrictions still in place in DL there was the decission to remove the nigh time from the contest period in Germany. For me this was a very unfortunate decission since this is usually the only time where i can operate without interruptions or other assignments.
In the afternoon there was quite some RS condition. I tried to find some QSO partner on 6cm but did not succeed. I heard DB0FGB (JO50), DB0NCO (JN59) and a OK station calling. The OK station did not come back to my call and i was not lucky in the ON4KST chat.
Videos of the beacons received:

Watch this video on YouTube.

Watch this video on YouTube.


Then i switched to 10GHz. Usually i am limited to direction south because of problems moving the dish through the upper roof window. This time i managed to put the little plastic dish outside to work some station to the north. At least DF0YY made it to the log this way.

Dish for 3cm on the roof top direction north-west


Jun21 3cm – (C) OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA) – created with DL4MFM log analyzer


Rig 3cm: FT-817, old transverter, 10W, 35cm dish with W1GHZ dualband horn
Result 3cm: 7QSO, 660p, ODX OK1FPR 200km

Later i tried 23cm. 10pm local time was already close. But i was not sure if i would be able to do some more QSO on sunday. So i decided to give some points to others outside DL at least and continued for a while. In the end i did not switch on on sunday again.

Jun21 – 23cm – (C) OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA) – created with DL4MFM log analyzer


Rig 23cm: HiQSDR, MKU13G3, 100W, 36ele
Result 23cm: 19QSO, 4600p, ODX HA5KDQ 550km

DUR 21/05

2 of 3 hours from home. Quite good on 23cm. Some nice QSO on 9cm. Unfortunately no QSO on 6cm.

21/05 DUR 23cm Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA), DL4MFM log analyzer


21/05 DUR 9cm Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA), DL4MFM log analyzer

Some more about SAW filtered LNA

The 1090MHz filters arrived and i measured this variant plus one without filter.

Closer to the filter the response looks quite ok:

LNA 1090MHz

Far away from the passband the supression degrades. Especially very high frequencies pass the filter quite well.

LNA 1090M span 3GHz

This is the assembly with 47pF capacitors and a 27nH coil for supply of the MMIC. Below 200MHz does not pass the capacitors well. There is even some remaining gain at 3.4GHz although its a 1.6mm thick FR4 PCB.

LNA without filter

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

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:

http://dh5ym.hopto.org/wiki/wp-content/uploads/2020/01/LA1UHG_JO59FB_23cm_20200101.aac

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

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.

http://www.dg0opk.darc.de/Octagon_LNB_mod_March2017.html

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:

http://www.pg540.org/wiki/index.php/PLL_LNB

Back to the OSLO:

Modification:

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