For those who have used Hristiyan’s transverters over the years, finally the 5.7 GHz version has been released. It has all the familiar IOs an programming methods of the existing transverters in the SG Lab range. If you weren’t aware, SG Lab is based in Sofia, Bulgaria and makes all sorts of microwave and RF products for commercial applications therefore they’re well-positioned to make amateur radio products. They’ve even adapted their commercial range for amateur radio use, such as their 5.7 GHz 10W PA.
the SG Lab 5700 MHz transverter has a frequency range of 5650 MHz to 5800 MHz, with a programable IF frequency range between 420 MHz and 450 MHz. Input power ranges from 200mW to 5W for a power output between 1.8W and 2.2W.
The cost of the 5700 MHz transverter as of February 2025 was 288 Euros with 10 Euros shipping to Australia. However, Hristiyan doesn’t have a page on his website (yet) for this transverter, so you’ll need to contact him for the latest pricing, shipping rates, and specifications.
If you’re keen to get on the 5.7GHz band, 3 paths include the Kuhne 5.7 GHz 250mW transverter, the Icom IC-905 2.5W transceiver, and now the cost effective SG Lab 5700 2W transverter. The 70cm IF suits QRP style portable transceivers such as the IC-705, FT-818, and the new Yaesu dual band FTX-1F. The IF is the same as the SG Lab 3,4GHz transverter and SG Lab 13cm transverter which makes switch between these to bands a breeze. All 3 transverters have programmable IF frequencies which means they can be set to any frequency you like in the 70cm band.
2 watts at 5760 MHz is more than enough to make many 100km+ contacts as it’s all about antennas and elevation at these frequencies. The transverter comes with a 5.7 GHz PCB antenna to get you going. Don’t underestimate these antennas as demonstrated in the 3.4 GHz antenna demonstration video.
Stability is important as frequencies increases, therefore the ability to lock the transverter to an external 10MHz source is a great advantage. SG Lab transverters are well built and are stable, so in other words, you’ll most likely get away using the internal reference.
The VK VHF UHF contest brings out many VK amateurs to test their gear and skills in making microwave contacts. VK3 has many active microwave operators and it’s not uncommon to have stations talking over each other on contest days.
MADs also promote monthly activity on the microwave bands with most of the activity being in VK3, VK4 and VK7. Subscribe to the VK3-Microwave and VKMicrowave email groups to stay informed of activity and join in.
There are three SMA connectors on the transverter.
The top SMA is 5760 MHz RX and TX. When the device is in split mode, it’s TX only.
The next SMA connector is RX only, but only when the transverter is in split mode.
Next, a 2.1mm DC jack allows 12v to be connected. The maximum current is 1400mA.
The 3rd SMA connector is the IF input. 420 to 450 MHz.
Next are two LEDs. The top is the Input LED, and the bottom is the output LED.
Finally a 3.5mm audio jack which allows the connection of an external sequencer.
Split mode is split-frequency operation option. It requires additional soldering. When enabled, it allows to addition of separate amplification on receive and transmit.
As of January 2025 Hristiyan confirmed the prices of SG Lab transverters as follows:
23cm band transverter V2.3 – 156 Euro
13cm band transverter V1.5 – 210 Euro
9cm band transverter V2 – 240 Euro
6cm band transverter V1.4 – 288 Euro
25W PA for 1296 MHz V2 – 162 Euro
20W PA for 2.4 GHz V2 – 126 Euro
20W PA for 2.32 GHz V1 with integrated RX/TX relay and LNA/BPF – 180 Euro.
You can confirm the price and order by sending Hristitan an email at in**@sg****.com
Version 1.4 allows the programming of alternate LO frequencies. This allows users to select a LO more appropriate for their needs. If none of the 8 pre programmed frequencies work you, then it’s possible to program your own – for example a 435 MHz IF. An example of how to program the transverter with a PC and USB-TTL cable can be found for the SG Lab 13cm transverter.
Default factory shipped LO Frequencies
5326 MHz (434 MHz)
5328 MHz (432 MHz)
5330 MHz (430 MHz)
5338 MHz (422 MHz)
The alternate factory shipped LO frequencies
5240 MHz (520 MHz)
5280 MHz (480 MHz)
5330 MHz (430 MHz)
5370 MHz (390 MHz)
To the maths…
If you select 5326 MHz as the LO, and tune to 434 MHz on the IF radio, you’ll be tuned to 5760 MHz.
| Minimum | Typical | Maximum | |
|---|---|---|---|
| Frequency range RF | 5650 MHz | 5760 MHz | 5800 MHz |
| Frequency range IF | 420 MHz | 432 MHz | 450 MHz |
| Local Oscilator Frequency | See Document | ||
| LO Accuracy at 20øC | +/- 0.5 ppm | ||
| LO temp. stability -20 +70øC | +/- 0.5 ppm | ||
| Output Power | 1.8 watts | 2.0 watts | 2.2 watts |
| Power Supply | 11v | 12v | 15v |
| Current Consumption RX | 0.26A | ||
| Current Consumption TX | 1.35A @ 2W | ||
| Input Power | 0.2 watts | 5 watts | |
| Receive Gain (Adjustable) | 0dB | +15dB | |
| Noise Figure (Split mode) | 1.5dB | ||
| Noise Figure (Rx/Tx mode) | 2.4dB | ||
| Dimensions | 124x94x30mm | ||
| Spurious response | Less than -50 dBc |
These photos show how I built the transverter into a diecast aluminium box. There’s also a 12v LiPo battery that allows easy operation when portable. It has its own BMS which charges when the transverter is plugged into a 12v source.
I’m in the process of making a video to show the results of testing the SG Lab 5.7 GHz transverter up against the Kuhne G4. Transmitter power just hits 2W in CW with 3W of drive from the IC-705 but interestingly the power output slowly falls to about 1.85W with a 10 to 15 second transmission. The transverter output stage is not wideband. The output power will be reduced the further away from 5760 MHz you go.
Initial on-air tests with Rob VK3IE found the receiver was very similar to the Kuhne on the same radio (IC-705) with the same antenna and feedline. Watch this space.
The transverter has an internal DC/DC converter from 12 to 28V for the output stage. If the supply voltage is lower, output power can be lower.
After finishing the benchtop tests, it was time to take the boxed-up SG Lab transverter into the field. A spontaneous 5 GHz microwave event happened where Rob VK3KRD packed up his 250mW Kuhne transverter and made his way to Mt Kororoit near Diggers Rest. I took both the SG Lab and Kuhne transverters to the top of Mount Martha. Several other stations joined us including Ray VK3ACR, Rob VK3IE, Neil VK3BCU, Paul VK3MVS and Gavin VK3HY.
The Kuhne was used as a reference as it’s a known quantity, as well as being GPS locked. The SG Lab transverter sat on top of the Kuhne and shared the IF Radio (IC-705) and a panel antenna. A small run of heliax joint the transverters to the antenna. Having got Rob VK3KRD and Ray VVK3ACR to turn their antennas away from me as they were way too strong, I asked them to take note of the frequency, signal strange and stability of the GPS-locked Kuhne to compare with the SG Lab device.
The SG Lab receiver was on par with the Kuhne. It was just as sensitive if not marginally better than its competition. There was a bit of QSB on the weaker stations but all in all, the receiver is great! The Kuhne system transmits 10W and the SG Lab claims 2 to 2.5W but I’m calling it 1.5W. The strength of the transmission received at both Rob and Ray’s locations was as expected with a slightly weaker signal, but still very strong.
The stability of the SG Lab device using it’s internal local oscillator (no GPSDO) was impressive. It was only a few hertz lower than the Kuhne. Neither Rob nor Ray detected any frequency movement on the long QSOs and it had only been powered up for around 5 minutes before the first transmission.
The long-awaited SG Lab 5.7 GHz transverter would have to be the most cost-effective way to get on the 5.7 GHz band when compared to most other offerings on the market. At the time of writing, it costs 288 euros, which equates to around $500 AUD landed here in Australia. Add a panel antenna for a hundred or so dollars, plus the QRP radio you most likely already have, and you can join the merry band of microwavers who participate in Microwave Activity Days and contest around the country.
If you’re keen to add an amplifier, SG Lab make a 10W 5.7 GHz amp and have a 15 to 20 watt PA with integrated RX/TX switching and LNA in development.
