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SG Lab 3400 / 432 MHz Transverter V2

SG Lab 3400 MHz Transverter review

This is the second SG Lab transverter that I’ve purchased. Ther first was Hristiyan LZ5HP’s 2400 MHz transverter which has worked flawlessly since day 1. Located in Sofia, Bulgaria, SG Lab makes all sorts of microwave and RF products for commerical applications therfore they’re well positioned to make amateur radio products.

The cost of the 3400 MHz transverter as of February 2020 was 240 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. This tranverter appears to be still under development as Hristiyan has been communicating with a few local VK amateurs.

Why buy this transverter

If you have an interest in getting on to the higher bands, SG Lab transverters are ideal. Above all, they are great value for money, and unlike some other companies that supply microwave equipment like this, the cost of shipping is economcal. They can have the same IF which means you can build the 2300 MHz transverter and the 3400 MHz transverter into the same box, in effect making your own dual bander. 3 watts at 3398 MHz is more than enough to make many 100km+ contacts as it’s all about antennas and elevation at these frequencies. SG Lab also have a 1296 MHz transverter but this device has a 144 MHz IF.

 

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.

Band activity

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.

 

The summer 2020 VHF UHF contest saw microwave activity from VK3MY, VK3FS, VK4WIS, VK4GU, VK5NE, VK1KW, VK2AZ, VK2XAX and VK4OE. All of these stations were home stations. Portable stations included VK3ALB, VK5KK, VK5ZD, VK5OI, VK7TW, VK5ZT, VK5OQ, VK2SRC, VK5BWR, VK3ER, VK4IF, VK3KQ, VK7OTC, VK3FSK and VK3BEZ. As you can see, plenty of stations running 2.4GHz and up.

There are many active microwave communities in Southern Queensland, South Australia and Tasmania. It’s worth joining the Facebook VHF UHF Microwave – VK ZL Group to see who’s out doing what and when.

Microwave Activity Days are held Australia wide from time to tim which gives everyone the opportunity to get out the shack and find a hill to work others. These days can be a lot of fun especially if the weather is kind. It’s worth keeping an eye on the VHF UHF Microwave – VK ZL Amateur ham radio Facebook group for upcomming MADs.

Transverter connectors and indicators

Side of the local oscillator on the SG Lab 3400 transverter

There are three SMA connectors on the transverter.

 

The top SMA is 3380-3480 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 1300mA.

 

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.

SG Lab 3400 transverter

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Features

  • 430MHz IF (programmable)
  • 200mw to 5w drive
  • Frequency range 3380 MHz to 3480 MHz (VK 3398)
  • 12v DC nominal power spply
  • 3 watts output power
  • Low noise figure – GaAs pHEMT input stage
  • High performance UP/DOWN converters
  • Hih stability TCXO
  • Input for 10MHz external reference oscillator
  • Internal TX/RX switch
  • Posibility to split TX/RX
  • Internal direct coupler
  • Output SWR indicator
  • Optimal input power indicator (bi colour LED)
  • Integrated sequencer
  • 4 Local Oscilator frequencies

Local oscillator programming

Version 2 allows the programming of alternate LO frequencies. This allows users to select a LO more appropriate for local conditions.

 

Default LO Frequencies

2968 MHz,
3024 MHz,
2970 MHz,
3026 MHz

 

The new alternate LO frequencies

2968 MHz,
2966 MHz,
2963 MHz,
2960 MHz

 

To the maths…

 

Desired Frequency – LO Frequency = IF frequency

so… 3398 – 2963 = 435

 

If you select 2963 MHz as the LO, and tune to 435 MHz on the IF radio, you’ll be tuned to 3398 MHz.

jumpers for programming the local oscillator on the SG Lab 3400 transverter
Jumpers for programming the local oscillator.
Specifications

3400 / 432 MHz Transverter V2

MinimumTypicalMaximum
Frequency range RF3380 MHz3480 MHz
Frequency range IF420 MHz432 MHz450 MHz
Local Oscilator FrequencySee Document
LO Accuracy at 20øC+/- 1ppm
LO temp. stability -20 +70øC+/- 2ppm
Output Power2 watts3 watts
Power Supply11v12v15v
Current Consumption1.2A1.3A
Input Power0.2 watts5 watts
Receive Gain (Adjustable)0dB+10dB
Noise Figure (Split mode)1.3dB
Noise Figure (Rx/Tx mode)1.7dB
Dimensions124x94x30mm
Spurious responseLess than -55 dBc
Sensitivity and Power Output

Receiver Sensitivity

 

The reciever sensitivity is reported to be very good. Here’s a test quick reveiver sensitivity test by VK2XAX. I believe this may be the V1 transverter.

RF Power Output

 

In another test by Tim VK2XAX on the adjustment of the output power of the SG Lab 3400 MHz transverter.

Getting the transverter on air

IF Radio

 

Most, if not all transverters are driven by a 10 watts or less. Using QRP radios such as the Yaesu FT-818 is an ideal and safe way to drive a transverter. High power radios tend to spike with high power on TX. This is ALC overshoot can destroy some transverters. ALC overshoot, or power overshoot, is caused by the basic flawed design of ALC circuits and RF power control systems. Using QRP radios will ensure your investment will give years of flawless use. Just look at all the microwave videos on Youtube to see what IF radios people use.

Yaesu FT-818
Yaesu FT-818

The future of 3.4GHz in Australia

 

There has been lots of talk about the future of the 3.4GHz allocation in the Australian amature radio band. Certainly, 3400MHz and up has been withdrawn for city allocations because of the rollout of 5G mobile networks amongst other things. At the time of wring ACMA are looking to change the allocation of the band, however the specrum below 3400MHz seems likely to remain untouched for the forseeable future. Use it or lose it as they saying goes…

Proposed prohibited 3400-3475 3575-3600 MHz in AU
Proposed prohibited 3400-3475 3575-3600 MHz in AU

Antennas

 

Popular, and common antennas for 3400MHz includ gridpacks, panels and dishes. One very popular antenna is the MT-405013 3.3-3.8GHz 18.5dBi Antenna. They have a flat VSWR or 1.5:1 across the band and don’t like any more than 6 watts in. Perfect for the SG Lab 3400 transverter.

2 3.4GHz panel antennas on bench
3.4GHz panel antennas

These antennas became popular with the GARC kit. You can read about the project at the Geelong Amateur Radio Club site.

Geelong Amateur Radio Club project

If you’re looking to pick up a pannel antenna, eBay and VKClassifieds may be you best option. If a gridpack is more your thing, you’ll find them at Radio Specialists in South Australia marketed as WiMax antennas. Alternatively, ask at your local radio club or microwave Facebook group as there are a lot of these antennas gathering dust in garages.

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