Monday 27 June 2016

UT5JCW 4 Meter Transverter Reveiw

I was lucky enough to spend this weekend playing with an old Deecom 4m HB9CV beam antenna and as this coincided with the 4m cumulative contest I decided to give my portable station a workout. This flurry of activity was spurred on by the many thunderstorm that have triggered sporadic-E openings well into this summer. My hope is to go and activate a local SOTA site this Autumn.

My backpack station now consists of a 70MHz transverter, a fishing pole mounted HB9CV beam antenna, a Yaesu FT817ND transceiver and a homebrew 12V power pack.

Supplied transverter PCB
Serge (UT5JCW) produces transverters for bands from 50MHz right though to 430MHz and I can confirm the 4M PCB is slightly larger than a credit card, it makes use of mainly SMD components with the exception of Inductors and the PA transistor. The PCB is supplied fully aligned and produces in excess of 10W when running from my gell-cell portable power pack. After carefully adjusting the transceiver drive level I did some quick tests which proved a nice clean output on 70MHz, with a second harmonic 39dB down on the fundamental. The close in emissions noted at 84MHz (2 x the local oscillator crystal at 42MHz) were better than 40dB down on the output signal.

So after extensive bench testing, I've finished boxing up my transverter and made several successful 4M band SSB contacts using my newly acquired Yaesu FT817ND as the driver. 

Rear of supplied transverter PCB
The receive sensitivity seems similar to that of the drive transceiver on 28MHz and the only problem noted was a slight frequency skew in transversion, of plus 5.8kHz. However, I didn't view this as a deal-breaker as this can be programmed out in my home QTH transceiver and mentally accommodated when out portable .

Serge did suggest that a suitable inductor could be connected in series with the crystal to drag it on frequency, but the PC board is so neat it seemed a shame to start hacking it around. Surge commented that in order to keep the price down of the product he had used computer grade crystals that were not noted for their accuracy.

Included in my box is a variable 30dB power attenuator, as suggested by Serge in the application data, as the transverter only requires 100mW drive - maximum! I also added to my project an RF activation circuit to operate antenna changer-over relays, as the barefoot transverter PCB has no switching hardware. A separate socket was added to make use of the grounded PTT line which is available on the ACC socket of my FT817. 

My boxed transverter including power attenuator and relays, the heat sink is from a faulty industrial PC
Overall this transverter represents good value for money and since I purchased mine, Serge has added some accessories that make its application even easier - as he now offers a ready made relay and power attenuator PCB. In fact you can buy a whole kit including the case for approximately £80 - see his  Ebay Transverter Store.

Many thanks to Serge UT5JCW for his prompt help in answering my technical queries and use of his circuits diagrams and photos in this blog. 

Transverter technical specifications
  • RF range  -   70 ... 72MHz
  • IF range  -  28 ... 30MHz
  • IF input power  -   1 ... 100mW (0.1W max.) or 0 ... 20dBm
  • LO frequency  -   42 MHz
  • LO frequency stability  -   +/- 3ppm
  • Output power  -   10 ... 15W
  • RX gain  -   typ. 20dB
  • Noise figure  -   typ. 1.0dB
  • Image rejection  -    typ. 70dB
  • PTT control  -   Contact closure to ground
  • Supply voltage  -   +13.8V DC (+12 ... 14V DC)
  • Current consumption  -   typ. 2A (TX)
  • TX Output transistor  -   RD16HHF1
  • RX Input transistor  -   BF998
  • Dimensions (mm)  -   80 x 45