Project Bench – Story’s

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Like to see some suggestions or projects in here. (how about offering some stuff so we can all read about it)

The receiver has a gain 32dB max with a NF of 1dBF. Rx gain ranges is 25dB.
 

 

VK4MJF has been putting the covid19 lockdowns to good use. Mini Kits supplied a EME227  23cm Transverter and VK4AMG offered to assist with the design and building process, and the eventional commissioning of the gear. We started with the Mini Kits 23cm Tranverter block diagram around April 2020 made some interesting changes to the original design. Changing the Local oscillator ( by using a ADF4351signal source pair with a mini USB Nano and a Isotemp 10MHz OXCO programmed) a couple of PGA103 LNA’s placed were need. All item were purchased from MiniKits and the white web and the process was in motion. Fastforward to November2020 and the project was in the completed stage with testing revealing a real transverter was alive, maybe a little low powered in some stages. With the power amplifier (RA18H1213G) installed ready to go, on power up tests  it was found the LO was not producing the db required to drive the next stage and a faulty amplifier module (made in China) would again slow the project down. Early December2020 we purchased some RA18H1213G from a reliable source and the process continued. By mid December the project was now nearing completion and VK4AMG had put his magic touch to produce 40 Watts (Yes ???) in his words “.

With that fixed the LO makes +13.5 dBm, the sort of figure I would have expected. ADF4351 output was low for this one (0 dBm – should be +5dBm). But that still drives the ERA-2 MMIC to saturation (data sheet says +13.0 dBm). I have tested every stage of the transverter.

I am reasonably confident it goes. PA makes lots of power (40W ??) and draws upwards of 5.5 A if given its head. I am concerned that at these high levels it is unstable. I have further tidied up the PA stage since the transmitter tests. Input and output coax cables shortened and separated. Supplies to the PA fed through feedthroughs. I have filed the anodising off the face of the heatsink in an effort to provide the best ground plane for the module and PCB.  I think it would be prudent to encase the PA module in a shield.”

MJF will report on the on air performance in due course. It was reported that the EME227 specifications were possibly a little overstated and other components were substituted were required. Also would like to thank George(VK4AMG) for his invaluable assistance and knowledge to complete this Project.

Projects new specifications.

The major problems (not up to spec) include bandpass SAW filter have a loss closer to 6dB than the specified 1.5 dB insertion loss, the transmitter amp MMICs are each short 2 to 5dB gain, the receiver amp MMICs didn’t last through the test phase (replaced with PGA103 and ERA2 respectively), power supply rx/tx switch modified to work at higher current drawn by receive amp and preamp.

 

 

VK4CRO  has been restoring his Alpha 76A, he has been working on the restoration for some years. So with a small outlay and lots of time here is the results,of course it comes with the brag about this 2K/watt Amplifier and the melting dipoles.

Looks even meaner in person

Looks even meaner in person

 

 

 

 

VK4MJF is working on 2.4ghz pre amplifier, for his 2.4ghz transverter. His story goe’s like this” after been embarrassingly beaten by several of the Klune 2.4ghz series of transverters on a recent shoot out with the VHF Group”, he decided to adapt a mini kits 2.4-2.6ghz pre-amplifier, achieving from a 5/4 to a solid 5/9 signal from the beacon @ VK4NEF QTH. Its almost finished he reported, and it will be trailed at  the next field day in September.

 

A bit more too go.

A bit more too go.

Second item on project.

The Khune Killer

The Khune Killer

 

Just needs a couple of small capacitors

Just needs a couple of small capacitors

 

 

 

 

Finished Project, VK4MJF has reported the finished project. He said all components excepting the mini kits 2.4-2.6ghz pre-amplifier, and W6PQl 12v to 28volt boost (supplied by Mick Normans whorehouse VK4NE) were all recycled from a past 2.4ghz amplifier project, so the cost was kept around the $100.00. He also tested the project and is very impressed with its ability to boost the beacon signal by 4-5 S points hoping that this will translate to a better reception on field days.

 

Another 70cm Amplifier was commissioned this week the second in the series of club projects another is being worked on as I type. Our thanks goes out to George(VK4 AMG) for his assistance to make them do what amplifiers do.

 

 NEWS / Club Meetings. MtGravatt TAFE 7-00pm 2nd Tuesday of the Month, 2 metre net every Tuesday 7.00pm with ZOOM.
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