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

LNA with SPF5043 and SAW filter

A while ago i tried the Eagle import capabilities of Kicad. I used a design of the baloon experimenteer “TT7” from Czech Republic and did some modifications to the layout. Since the LNA looked promising i sent the design for production and ordered some components. I had to replace some components for easier sourcing.
The MMIC i replaced with the compatible type SPF5043. Instead of the 3.3V regulator i used the variant with 5V output and up to 16V input. The options for the SAW filters are limited. The 70cm filters usually allow for the lower half of the band but the curve will degrade around 437MHz. A filter for 23cm and one for 13cm was availabe as well. The same for 1090MHz. Unfortunately none for 405nm was available. There is an option for phantom feed of the LNA as well as mounting an ESD diode. Unfortunately i did not care about the width of the RF traces. They are far to wide. Fortunately the trace in front of the MMIC is short.

SAW filtered LNA


For test i assembled one board for 70cm, 23cm and 13cm each.

LNA 70cm


As written above the 70cm SAW starts to attenuate a lot around 437MHz. There was a type with broader response but it is available nowhere.
The overall gain is about 18..19dB which is in line with MMIC and filter datasheet.

LNA 70cm wideband


Looking to the wideband response of the filter reveals that it looses its filter capabilities over 1200MHz.

LNA 23cm


The filter used for 23cm is a bit wide. It exceeds the amateur allocation a lot at the lower end. At the upper end 1296MHz is already at the edge. The maximum gain is around 1180MHz with 13dB. For 1296MHz it results in roughtly 8dB gain only.

LNA 23cm wideband


The filter capability is maintained over a broader range and de-rates at over 5GHz.

LNA 13cm


The filter for 13cm fits pretty well. Although the MMIC has even less gain the filter also has less attenuation than the 23cm type on 1296MHz. Therefore it also results in about 8db gain.

LNA 13cm wideband

DARC 10m Contest 2021

This year i spent quite some time in preparation of the 10m contest. Already a year ago i bought some fishing rods with the plan to make a Moxon antenna. This antenna was realized now. The transceiver was my HiQSDR again driving a R155 PA. In order to improve sensitvity i connected a wideband LNA from Funkamateur. The LNA was switched on and bypass by one of my sequencer PCBs. Quisk SDR forwarded 192kHz IQ samples to skimmer and from there the decodes went to the bandmap of tlf log. I started in CW and worked quite some multies. After one hour i changed to SSB which was a likely a fault because the activity in phone was low. The last 30 minutes were spent in CW again.
The map below shows the locations of the stations worked. They were taken from internet and might be incorrect. The map shows that i mainly had the moxon to north and west direction.

stations worked in 10m contest 2021 – maps by openstreetmap and opentopo contributors via DL4MFM edi analyzer


The most heavy part of the moxon is the mounting plate. The fishing rods are snapped to the plate and then fixed with U brackets. There are 16 wing nuts to fix.

10m moxon antenna under test indoor


Getting the antenna outside is not that easy. It needs to be mounted outside and there was little space because of a chimney nearby.

Moxon antenna mounted outside the roof window


It you do not take care everything will end up in a big mess.

Gordons knot – wires of the moxon


The software did cosist of Quisk, skimmer and tlf log.

SDR software just before the contest


The R155 PA can generate 100W with 5W input. Unfortunately it seems not very robust against some RF nearby. The linear power supply i tried to use before went unstable in SSB. Therefore i had to swap the supplies.

PA and power supply


HiQSDR is quite unsensitive on 10m. I used a LNA from Funkamateur which has bypass relais for TX. I had to replace the transistors because both where faulty.

HiQSDR and preamp

December DUR

The last DUR activity of the year was out of competition due to the new restrictions with respect to Covid-19. Therefore the portable activity was low.
23cm ended with 12QSO and ODX DL1SUZ about 300km. I several times tried with HA8V without any success. Also other signal appeared quite weak. I heard Uwe on 13cm as well. Since i do not use a PA yet (only 1W) i was not able to make a QSO there. 13cm finally had 6 QSO, everything local. On 9cm i was able to reach DL6ABC and DC7QH in Berlin + DL4DTU locally.

Marconi Memorial Contest 2020

Due to partial lockdown no multi-op activity. Other weekend activities cancelled as well, so found some time to participate the MMC from home.
The setup was my usual HiQSDR + ME2HT + 200W Transistor PA + 4 ele.
About 11h operating time resulted in 134 QSO with ODX 730km..

It was pretty obvious that almost all the big multi-op teams where missing. Still some good DX oportunities even for my tiny station.
IQ3AZ was super loud. The attempts with SM6VTZ and YO5LD failed although we heard each other for short moments.

TOP 10 DX QSOs:
——————-
9A8D JN95LM 731 km by DH5YM
9A4M JN85EI 669 km by DH5YM
IQ3AZ JN65QQ 602 km by DH5YM
S51S JN75ES 595 km by DH5YM
HA6W KN08FB 592 km by DH5YM
HG1A JN86MM 564 km by DH5YM
9A5RJ JN86EL 550 km by DH5YM
PA0O JO33HG 539 km by DH5YM
HB9FAP JN47PH 529 km by DH5YM
S59P JN86AO 528 km by DH5YM

Marconi Memorial Contest 2020 // Image created by DL4MFM log analyzer. Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA)

2020 October DUR test

Recently my new 23cm LNA showed up here. For the DUR activity contest today i integrated it into my transverter system. 9cm got double points this month. Therefore i also tried to be active there. Not that much activity and only 2 QSO. The 23cm result was quite good due to some nice DX with SM6VTZ, HA5UA, HA5YA and OM5CM.

23cm result October DUR // Image created by DL4MFM log analyzer. Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA)


New 23cm LNA


23cn and 9cm antenna

2020 October UHF/SHF

Originally planned some more QSO but in the end there where more time constraints than expected. Therefore only 21 QSO on 23cm sunday morning. I skipped all other bands. 70cm was not ready anyway. ODX HA5KDQ with >500km.

Image created by DL4MFM log analyzer. Kartendaten: OpenStreetMap-Mitwirkende, SRTM | Kartendarstellung: OpenTopoMap (CC-BY-SA)

IARU VHF contest

I planned to make some QSO from home. In the end i had about 10h of participation mainly during the night and sunday morning. The setup was 4ele and 200W with my HiQSDR and ME2HT transverter. The raw result shows 95QSO with highlights YT4B in CW random and IQ5NN even in SSB via aircraft scatter. 7S7V and 5P5T had pretty strong signals here.

Log results DH5YM September 2020 – visualized with DL4MFM log analyzer – (C) openstreetmap contributors

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