[Amps] RF-Kit RF2K+

[Paul Christensen]

>From Mark, NU6X who is not yet a list member:

 

 

“I have been reading the threads on the RF2K+ offered by RF-Kit.de and would like to clear up the confusion. I have been trying to join the list but have not gotten confirmation yet. Paul, W9AC, has offered to pass this info along.

First, I want everyone to know that I am NOT an Agent or Employee of RF-kit.de. I am an interested Ham who discovered their development and have built several of their linears. I have volunteered to work on the English version of the Manual and helped develop the test procedures.  I have no financial interest.  

RF-kit.de is a group of Hams in the B26 radio club area of Germany who started  this project several years ago. It did not started as a commercial venture.  When I first discovered their project, everything was in German. The website was never intended to be a marketing site as it was being used to help communicate their progress and development in Europe. It is confusing as it has a lot of information about the progress of development over the last few years and over a  range of different modules that were tried. With the completion of the new SWR Bridge  and Low Pass Filter (LPF), all the modules are manufactured in Germany.    

They use to offer the controller and RF pallet individually but that has been discontinued. It is only offered as a kit with an optional Tuner....The LPF and Power Supply is included.

I hope the following  doesn't sound like a sales pitch  but here are the facts:

    The RF2K+ is a partial kit that includes all the items needed  except 3 fans, a Raspberry PI 3, and an attenuator. These remaining items need to be purchased by the builder and cost about $100. 
The kit  includes:
            1) RF2K+ pallet with two BLF188XR  mounted on a fully machined copper spreader 
                    and a 120MM x 120MM x 250MM special heat sink            
            2) 3KW built in switching power supply modified for quiet fan operation
            3) Cabinet/Enclosure
            4) Controller board with on-board Arduino Processor
            5) 7"color  touch screen
            6) Low Pass Filter .. 160-6 meters
            7) Precision SWR Bridge using log amp RF detectors
            8) Optional Auto Antenna Tuner 3:1  
            9) RX/TX relay board - 1 input , 4 antennas outputs
            10) All needed connectors, cables and stainless hardware
            11) SD card software and  lifetime free updates
            12) 1 year warranty on boards and modules excluding the BLF188XR devices  

The kit comes mostly assembled and tested requiring  the builder to :
         1) Mount the Raspberry PI and plug in the cables.
         2)  Mount and wire three fans.
         3) Prepare and solder 4 or 5 silver Teflon RF cables (cable supplied)
         4) Test and calibration requiring a wattmeter and DVM.   

This linear is a legal limit amplifier  is capable of more so there is a lot of headroom. The builtin Power Supply was chosen for its very low RF noise. It is a commercial product and rated at 3KW continuous duty at 53.6 Volts. Since the RF pallet runs at 65 -70% efficiency  it has plenty capacity. It has been modified with a different cooling arrangement to reduce noise. 

I could write a book on all the factors on IMD3 testing and the different tricks I have seen and  how they are reported.  It isn't very hard to get good IMD 3 numbers at 14mhz and above but more difficult on 80 and 160M. Also just a few hundred watts into  compression causes a rapid increase in IMD3. I have seen clean spectrum displays but later found the power level was at reduced output.  This pallet uses two BLF188XR LDMOS devices  that are rated at 1400 watts output each for a total of 2800 watts. It very difficult to get clean SSB signal out of a single device. This is why most manufactures have gone to a pair.  The RF2K+, when run at legal limit,  is in the very linear range of these devices and has excellent IMD 3 and IMD 5 performance.  I invite anyone to my QTH (Sedona, AZ)  to see its performance on my Spectrum Analyzer. This is not CB or eBay junk.

I saw some discussion about current  limiting to control output. This  is false , the pallet has builtin current limit as protection along with SWR and input power protection. The amplifier doesn't reduce power under high duty cycle, instead it is designed to handle the high duty cycle.

The latest addition to the kit is the new Low Pass Filter. Toroid size and material were chosen to handle 2 KW. Harmonics reduction is down 50 db or more  which  surpasses FCC requirements. Each LPF is tuned by RF-kit.de  with a Vector Network Analyzer (VNA).

The amp uses two 120mm radiator type fans in a push pull arrangement for cooling. I have been experimenting  with a dozen different highly rated fans and can make recommendations. I built a test fixture to measure air flow and noise level to eliminate any subjectivity.  More air and more cooling doesn't always mean more noise. The PA fans are controlled  by PWM from the controller. 

The Raspberry PI provides great connectivity via WiFi, Ethernet/LAN, direct CAT,  standard BCD and Icom CI-V. It is easily remotely operated. The Raspberry PI also checks for software updates and will automatically load them. 

It is my understanding that the Yahoo group and website will be re-done soon and will be more informative. Pricing needs to be confirmed by email (mail at rf-kit.de <mailto:mail at rf-kit.de> ) but it was offered at Dayton for $2685 with out tuner and $2985 with tuner. Some confusion may be euros vs dollars. The above was US dollars.  FedEx Air from Germany runs around $170. I got my last kit in 3 days.  

There was a question on the red front panel. The cabinet, front and rear panels are anodized aluminum. They can offer a custom front overlay (plastic NOT thin vinyl) in many color schemes. The rear panel labels  are laser cut. This is a professionally manufactured cabinet.

The dimensions are 7 1/2"h x 12" W x 17" D and weights around 33 to 35 lbs. 

My email is good on QRZ. Please send all pricing and order request to mail at rf-kit.de <mailto:mail at rf-kit.de> 

73....Mark NU6X  Sedona, AZ”