Category Archives: Microwave

Octagon OSLO TCXO Modification

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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

PlutoSDR operation and some microwave beacon

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Below i add some short videos i made. The first two show transmit and receive operation of the PlutoSDR in the 6cm amateur band. I used the great sdrangel software. The opposite side is my normal 6cm rig consisting of a FT-817 and a DB6NT transverter.

The third video shows 3 of the DM0TUD microwave beacons that are located close to my home. It is from right to left: 13cm (FT-290), 3cm (FT-790R2), 9cm (FT-817).

Watch this video on YouTube.

Watch this video on YouTube.

Watch this video on YouTube.

4m access in DL / 13cm&6cm for class E

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German BNetzA released notifications 414/2018 and 415/2018. Those extend the permission for class E operators to work in the 13 and 6cm band as well give a new permission for 4m band access in DL. On 4m class A will be allowed from now on to Dec.31 2019 to work between .150 and .200 with 25W ERP max.

DUR 1810

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Working from home again. Only south direction 140-220°.It seems the participation in that direction was not that good. I need to put some antenna over the roof for 23cm at least.

Right side: yagies for 23/13cm, panel for 9cm. Left dish for 3cm. On the floor in the right corner dish for 6cm.

microwave rigs

 

Band QSOs Punkte AVG
1,3 GHz 5 266 53.2
2,3 GHz 7 178 25.4
3,4 GHz 1 8 8.0
5,7 GHz 1 8 8.0
10 GHz 1 8 8.0

Band 1,3 GHz

QSOs:             5
QSO-Punkte:       266
Punkte:           266
Durchschn. Pkt/QSO:   53.20
Durchschn. QSO-P/QSO: 53.20
Punkte/50 QSOs:     266
DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20181021 SSB 08.30 DH1DM 59 001 59 013 JO60VR 42 DH5YM
20181021 SSB 08.30 DG2DWL 59 002 59 013 JO60VR 42 DH5YM
20181021 SSB 08.32 DG5VL 59 003 59 002 JO61WA 14 DH5YM
20181021 SSB 08.48 DL4DTU 59 005 59 013 JO61TB 7 DH5YM
20181021 SSB 11.02 OK1FQK 59 006 59 021 JO70NA 156 DH5YM

Band 2,3 GHz

QSOs:             7
QSO-Punkte:       178
Punkte:           178
Durchschn. Pkt/QSO:   25.43
Durchschn. QSO-P/QSO: 25.43
Punkte/50 QSOs:     178

 

DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20181021 SSB 08.37 DO1UZ 59 001 59 004 JO60SX 18 DH5YM
20181021 SSB 08.50 DL4DTU 59 002 59 008 JO61TB 7 DH5YM
20181021 SSB 09.14 DO5UH 59 003 59 009 JO60WT 34 DH5YM
20181021 SSB 09.17 DG2DWL 59 004 59 008 JO60VR 42 DH5YM
20181021 SSB 09.17 DH1DM 59 005 59 008 JO60VR 42 DH5YM
20181021 FM 09.21 DM4SWL/P 59 006 59 009 JO61XA 19 DH5YM
20181021 FM 09.22 DM7MM 59 007 59 005 JO61UA 9 DH5YM

Band 3,4 GHz

QSOs:             1
QSO-Punkte:       8
Punkte:           8
Durchschn. Pkt/QSO:    8.00
Durchschn. QSO-P/QSO:  8.00
QSOs/Stunde:        1
Punkte/Stunde:      8
Punkte/50 QSOs:     8
DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20181021 SSB 08.53 DL4DTU 59 001 59 001 JO61TB 7 DH5YM

Band 5,7 GHz

QSOs:             1
QSO-Punkte:       8
Punkte:           8
Durchschn. Pkt/QSO:    8.00
Durchschn. QSO-P/QSO:  8.00
QSOs/Stunde:        1
Punkte/Stunde:      8
Punkte/50 QSOs:     8
DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20181021 SSB 08.54 DL4DTU 59 001 59 001 JO61TB 7 DH5YM

Band 10 GHz

QSOs:             1
QSO-Punkte:       8
Punkte:           8
Durchschn. Pkt/QSO:    8.00
Durchschn. QSO-P/QSO:  8.00
Punkte/50 QSOs:     8
DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20181021 SSB 09.44 DL4DTU 59 001 59 002 JO61TB 7 DH5YM

DUR September 2018

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DH5YM – DUR1809

Part time qrv from new QTH. Good takeoff direction south and nord. Only working direction south with very limited setup.
23cm 15W 14ele
13cm 1W ringfeed

Locator:: JO61UC
Band QSOs Points average
1,3 GHz 8 318 39.8
2,3 GHz 6 203 33.8

Band 1,3 GHz

Polar map for 1,3 GHz

DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20180916 SSB 09.11 DG0LFF 59 001 59 009 JO61VC 5 DH5YM
20180916 CW 09.19 OK1FJZ 599 002 559 011 JO60WD 107 DH5YM
20180916 SSB 09.23 DG5VL 55 003 45 010 JO61WA 14 DH5YM
20180916 SSB 09.24 OK1IEI 55 004 59 007 JO70EC 120 DH5YM
20180916 SSB 09.27 DH1DM 59 005 59 008 JO61TB 7 DH5YM
20180916 SSB 09.30 DG2DWL 59 006 59 025 JO60VR 42 DH5YM
20180916 FM 09.56 DG4VL 59 007 59 004 JO60VX 15 DH5YM
20180916 FM 10.27 DG1VT 59 008 59 001 JO61UC 0 DH5YM

 

Band 2,3 GHz

Polar map for 2,3 GHz

DATE MODE TIME CALLSIGN TX RX LOCATOR QRB OPERATOR REMARK
20180916 SSB 09.32 DO5UH 59 001 55 009 JO60ST 34 DH5YM
20180916 SSB 09.33 DG2DWL 59 002 59 012 JO60VR 42 DH5YM
20180916 SSB 09.35 DO1UZ/P 55 003 55 007 JO60RP 53 DH5YM
20180916 SSB 09.36 DL9NCI/P 55 004 55 007 JO60RP 53 DH5YM
20180916 SSB 09.58 DG4VL 59 005 59 002 JO60VX 15 DH5YM
20180916 FM 10.29 DG1VT 59 006 59 001 JO61UC 0 DH5YM

9cm DB6NT kit

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Now i started soldering the 9cm transverter kit that was in the shelf since years. The filter caps look already a bit oxidated. But soldering still worked fine. The new 9cm will get into a box together with 13cm at some time.

9cm DB6NT MK2 transverter partly assembled

[Update]
finished…

9cm transverter

6cm PA chain

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For my 6cm transverter i bought a 10W DL2AM PA years ago. Because it needs about 1W drive i combine it with the WLAN PA from here
6cm PA chain
The complete chain now has about 39dB gain and a P1dB of about 40dBm. So its working fine.

6cm PA chain output power


The current consumption for the both PA separately (orange driver current in mA, blue PA current in A).

6cm PA current consumption

A simple 9cm monitoring receiver

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Just for fun i tried to collect some components from the shelf and plugged together a simple monitoring receiver for 9cm.
I have a DF9NP PLL OCXO for 2592.2MHz and a pipe-cap filter tuned to 3400MHz. From China i ordered a wideband LNA some month ago. It has about 15dB gain on 9cm. The mixer is a ZEM-4300+ (+7dBm LO). The setup results in a IF of 807.8MHz which is received with an RTLSDR and the very nice GQRX software.
With a short wire attached to the input of the LNA i was able to receive the local 9cm beacon DM0TUD.

9cm monitor hardware


GQRX receiving DM0TUD 9cm beacon

Finally a 6cm horn antenna

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In this post [Link] i wrote about a 6cm horn for offset dishes from Russia. The horn was designed for 5720MHz and i was not able to tune it to 5760MHz were i wanted to use it. DG2DWL gave it another try and added a M6 tuning screw opposite to the feed tip. He managed to get the resonance to the correct frequency.
So with some modification these horns are a good alternative for offset dishes in the 6cm narrow band section.

russian 6cm horn tuned to 5760MHz

A chinese PA for 6cm

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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