SG Lab 1296 MHz Transverter review V2.3

1296 MHz is a great entry-level band for those wishing to move into the microwave part of our hobby. Although not technically a microwave band, 1296 MHz, or 23cm, is still a part of UHF spectrum. It’s a great band to start honing your skills in microwave RF as you move up to SHF.

This is the SG Lab 1296 MHz transverter that has an IF in the 2m band. Antennas and commercial receivers are readily available for this band, so it makes a great first step into the fun and exciting world of transverters. Located in Sofia, Bulgaria, SG Lab makes all sorts of microwave and RF products for commercial applications therefore they’re well-positioned to make amateur radio products.

The cost of the 1296 MHz transverter as of October 2020 was 176 euros with 60 euros shipping to Australia via courier. However,  you’ll need to contact SG Lab for the latest pricing, shipping rates, and specifications. This 23cm tranverter is used by many VK amateurs.  The new version (2.2) of the SG Lab transverter features better performance and some new functions when compared to the older version.

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 seriously great value for money. I only use SSB, so my opinions are offered with that mode in mind. With alternative configuration options, you can use repeaters and FM, but make sure you read the specifications to determine for yourself that it can do what you want it to do.

The IF (Intermediate Frequency) of the transverter is 144MHz. This means you’ll need a 2m SSB/FM transciever of no more than 5 watts to drive the transverter. For an RF output of 1296 MHz, you have a choice of 142, 144, or 146 MHz as an IF. I use 146MHz. I strongly recommend NOT using a transciever that is capable of transmitting more than 5 watts as small spikes well in excess of the maximum when you first transmit may damage the transverter. This is called ALC overshoot and applies to any transverter you may use.

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 transverter has a noise figure of 1dB. It also has a RF Vox switch meaning the device will sense RF on its input and TX or RX accordingly. The TX ground option is a much better way to key the transverter which avoids relay chatter if you’re using SSB and is available on the tip of a 3,5mm audio jack. You’ll find SMA connectors for interconnection between antennas and transceivers.  You can also split TX and RX out individual SMA jacks if required.

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. Generally speaking, you won’t find much activity on 23cm despite the large influx of the Icom IC- 9700s which have 23cm built-in. For some strange reason, these radios seem to be used as 2/70 radios.

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 time 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 upcoming MADs.

Transverter connectors and indicators

Features

• 2W output power
• Low noise figure GaAs HEMT input stage
• High-performance UP / DOWN converters
• High stability TCXO
• Internal Tx/Rx switch
• Split-frequency operation option (selectable, require additional soldering)
• Internal Directional Coupler
• RX/TX switching (PTT):
  • push PTT input to ground
  • RF VOX
  • apply DC voltage to coax cable
• Output SWR indicator – bi-colour LED
• Optimal input power indicator – bi-colour LED
• Integrated Sequencer
• Repeater operation option : -28 / -6 MHz LO shift TX (selectable)
• Working via repeater: default -28 MHz LO offset (selectable)

Local oscillator programming

LO Frequencies

1150 MHz
1152 MHz (default)
1154 MHz

Repeater mode Shift offered is -6MHz or -28MHz which is not in line with -20MHz required in VK.

To the maths…

Desired Frequency – LO Frequency = IF frequency

so… 1296 – 1150 = 146MHz
1296 – 1152 = 144MHz
1296 – 1154 = 142MHz

If you select 1150MHz as the LO, and tune to 146.1 MHz on the IF radio, you’ll be tuned to 1296.1 MHz which is the SSB calling frequency.

Price

As at April 2021 Hristiyan confirmed the prices of SG Lab transverters as follows:

23cm – 156 Euro
13cm – 210 Euro
9cm – 240 Euro

Tthe prices of SG Lab PAs as follows:

25W PA for 1296 MHz V2 – 162 Euro
20W PA for 2.4 GHz V2 – 126 Euro
20W PA for 2.4 GHz V3 – 138 Euro  Both V2 and V3 are one-way amp and are
used mainly for QO-100 satellite.
20W PA for 2.32 GHz V1 (terrestrial band) with integrated RX/TX relay
and LNA/BPF – 180 Euro

You can confirm the price and order by sending Hristiyan, LZ5HP, who is in Sofia Bulgaria, an email at in**@sg****.com

Specifications

Videos 

If you enjoy SOTA, parks, microwaves or radio in the great outdoors, then this is the radio for you. Having received many accolades, and a long list of positives, some might say there’s one thing missing on the IC-705 and that’s the 23cm band. There’s only so much that you can fit in a small portable radio, and Icom has done a really good job packing in as many features as possible so it’s understandable that the line has to be drawn somewhere. If you’re keen to build a 23cm transverter using the SG lab transverter, here’s one way to do that.

A walk-through of the SG Lab 1296 transverter and PA

This video by Haden 7HH takes you through both the SG Lab 23cm transverter as well as a quick look at the 25W PA.

23cm yagi Vs a bi-quad

Comparing the gain of a 23cm yagi over a bi-quad because you’ll need an antenna for your 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 Icom IC-705 or 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.

Mounting your Transverter and PA

You’ll need to mount your kit in a box or housing that’s suitable for how you want to use it. It’s possible to get two transverters in one 2RU rackmount box. Keep all leads as short as possible, and fuse everything. I use TX Ground to switch between transmit and receive and external sequencing and antenna switching is not required for this pair. There’s a provision to use an external 10MHz reference oscillator, but I find the inbuilt LO adequate for SSB. All in all, a very easy way to get into 23cms. It’s a great step towards microwave. Choose your IF carefully too. It’s 142, 144 or 146 MHz.

Antennas

Popular and common antennas for 1296MHz include yagis, bi-quads and gridpacks. These can be purchased or homemade. The only downside to making your own is the test equipment required to tune your antenna. Commercially there is a Diamond SX100 quadband power meter, but this can set you back $300. Ask about and see if a fellow amateur can help out.

If you’re keen to purchase a high quality 23 cm antenna, you can’t go past the antennas on offer from antenna-amplifiers. If you do go down this path, check out Goran’s range of antenna parts. Use every kilo your paying for. Remember, you get what you pay for. At 23cm, coax, plugs and connectors, as well as antenna components, become more critical for antenna efficiency.