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.
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.
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.
There are three SMA connectors on the transverter.
The top SMA is 1240-1300 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. 2m
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 the addition of separate amplification on receive and transmit.
1152 MHz (default)
Repeater mode Shift offered is -6MHz or -28MHz which is not in line with -20MHz required in VK.
To the maths…
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.
As at September 2020 Hristiyan confirmed the prices of SG Lab transverters as follows:
23cm – 156 Euro
13cm – 210 Euro
9cm – 240 Euro.
You can confirm the price and order by sending Hristitan an email at firstname.lastname@example.org
|Frequency range RF||1240 MHz||1300 MHz|
|Frequency range IF||144 MHz||148 MHz|
|Local Oscilator Frequency||1150 MHz, 1152 MHz or 1154 MHz|
|LO Accuracy at 20øC||+/- 1ppm|
|LO temp. stability -20 +70øC||+/- 2.5ppm|
|Output Power||2 watts||2.5 watts||3 watts|
|Current Consumption||850 mA|
|Input Power||0.2 watts||5 watts|
|Receive Gain (Adjustable)||-5dB||+10dB|
|Spurious response||Less than|
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.
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.
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.