Beyond FM:  Transverters

By Jim Aguirre, W7DHC

Previously, I discussed transceivers that provide all-mode capability on the VHF, UHF and microwave bands, along with a brief mention of transverters. In this article, we'll explore transverters more fully.

Transverters simply convert both incoming and outgoing radio signals to a different frequency by mixing them with a signal from a 'local oscillator.' Just remember the basic theory that when two signals of different frequencies mix, new signals are created that correspond to both the sum and the difference of the originals?

For example, by using a 28 MHz (10M) signal from an HF rig and mixing it with a 22.000 MHz crystal controlled local oscillator in a transverter, a 50 MHz output signal is created. (28+22=50). Filters remove the unwanted 6 MHz 'difference' signal. So, if you tune the 10M IF rig to 28.125 MHz and run the signal through a transverter, a 6M output occurs at 50.125. Similarly, the incoming 50.125 MHz signal is converted down to 28.125 MHz (50.125-22.000=28.125) to be received on the HF transceiver.

Today, there are three primary sources of transverters designed to work with a wide variety of transceivers. There are also many magazine articles and Internet sources on the subject of homebrewing transverters if you're the adventureous type.

TenTec currently produces very basic 6M and 2M transverters that, by most accounts, work pretty well. They are available as both kits or factory assembled units. Power out is usually 8 watts or less. The cost is in the $110 - $240 price range. One interesting aspect of the TenTec units is that one version uses a 14 MHz IF. Look in the TenTec web pages (off-site) for more information.

Probably the most common source of VHF, UHF and microwave transverters in the US is Downeast Microwave (DEM), a small niche manufacturer in Frenchtown, New Jersey. Owner Steve Kostro (N2CEI) offers a wide variety of equipment ranging from 6M through 3 CM (10 GHz). Most transverters are available as either kits or assembled units. Prices run in the $300-$400 range for the basic transverter. Power output ranges from about 25W on the lower bands to 1W or less in higher microwave ranges. Plan on spending a hundred dollars or more the first time around to get interface boxes, antenna changeover relays and other necessary items. You can get more info at Down East Microwave (off-site).

SSB Electronics, located in Mountaintop, Pennsylvania, also manufactures and distributes transverters. Their primary line is the LT series, with units covering 50 MHz through 2.3 GHz in the 10 to 30 Watt output range. These are generally a bit more expensive than the DEM units; $900 to $1,500 per transverter. SSB also handles imported German units designed by DB6NT and manufactured by Kuhne Electronics that cover the microwave bands from 1.2 GHz all the way up to 47 GHz! These units range from 2W output down to about 200 mW. Some models are available as kits. Prices run from $400 to $900, depending on the unit. You can check them all out at www.ssbusa.com (off-site).

Next, we'll explore VHF/UHF feedlines and connectors.