Fox receiver for 2019

Fox receiver

Prototyp

It starts in the spring this year, I help Bo SM5CJW to do some small receiver board he work with.  I save some boards for own use and later I get updated info from Bo. So I will give it a try.  I build the HF board and an LF board, the  Lo Si5351 i was familiar with earlier, it was also published in Swedish ham magazine QTC. After some change of mixer it works grate with excellent  sensitivity  and low noise level. Bo also have same example on different antennas, and I start to try with loop antennas . I really like the result. I build prototypes with both loop and ferrite antenna and as I see it the loop is the winner, 1 more shape on minimum signal, 2 more quiet, ferrite  has a small noise I didn’t  here in loop, 3 a little bit higher signal level.

I decide to try this receiver build together with my earlier built electronic compass. This was the hardest bit to put in 3.3V cpu together with an sensitivity receiver (around 0.5 uV) many filters and try and error to get all thing to work.

I start to merge the code to one cpu but I couldn’t  get it small enough, so way not run the Lo with Bos code on Attiny85 and do the rest with an Adafruit board Pro Trinket 3V. So this Fox receiver has 2 cpu!

Here is the result.

Sensitive receiver.

Excellent Front back or side decision.

Integrated compass direction  in display and calibration status .

Frequency information in display.

Battery voltage in display.

Signal strange meter in display.

Attenuator 0-80 dB info in display.

Look forward to test signal strange in practise, difference so far  95dB 1m from Fox compared to 3.5 km from fox.

I am relay glad I start this work has learn a lot.

Thanks to Bo SM5CJW for the receiver part.

QRP PA

QRP PA

QRP PA

See earlier work in December 2017. After that I made a PCB and have now mounted and tested the first board. It is inspired from K5BCQ and from  DK1HE QRP-PA.

Not as god as I hope, but working.

+10dBm iN,

OUT  @ 1.8 MHz  41,3 dBm

          @  7,1 MHz 43,3 dBm

          @ 28,4 MHz 41,0 dBm

          @ 52 MHz 39,2 dBm

RL < -15 1,8 – 52 MHz

Current 2,5 +/- 02A

I hope it will be in one more QRP transceiver  I have ides for, we will se!

There  is also an USB to serial board on the back panel.

I have some PCB over if you are interested e-mail.

Minima PA

Minima PA

I by  the Minima complete all mounted component in February, but i didn’t receive any so i by a new in April a kit 100W, after build it, i burn two transistor MRF 9120 so no idea to go on. Change to use IRF530 and skip 50MHz. And this works. After a try to made and measure on LP filter, all have high insertion loss  more then 1 dB. I decide to by one and to get ready with the PA. I found this on ebay

So a small board  with diode to fix the band select, and a regulator for the relays had to be done .

I already have an old led driver  LM3916 to monitor the power,  useful to monitor when struggling with the SDR parts!

Link to PA description Example Minima pa

Link to Filter

Result PA 1.8 – 30 MHz Output 45 – 75W ( drive max 5W) SWR 1.1 in 3.5 – 30 MHZ 1.2 @ 1.8MHz.

Hope to use it more in 2019!

Time for SDR

SDR

I am no retired from January 2018, time to do some more experience, i decide to try SDR technology. I will go for use Computer as a part. Then i found this Hobby PCB for reasonable price, see HobbyPCB.

After a lot of SW setup its run nicely with 4W out. 

I have now run around ten QSO by this unit in QRP.

 I wont to place the external sound card, also from Hobby PCB Startech 96KHz USB SoundCard and USB hub in one box, to get it more simple to use. 

Next is to get a PA to work together with tis equipment. I have already burn one simple with IRF530. So I will lock for a better one. I am definitely fast to this techniques, 96kHz of the band on the screen compared with turning one VFO. on the old station, it is like a new please in the Galaxy. I will sell my old transceivers.  I have already ordered a 2m transverter from Ukraine, hope it arrives this week. Hope to be on air in Mars VHF-Test     6 Mars. This is my next goal.

 Some fun things I like.

Calibrated S-Meter, continues controlled output-power, filter works grate, notch filter also.

Next goal is to get it running with WSJT-X sw for digital modes.

Stay tuned. SM4HNG

PA for 1296 MHz

Since i was finished with the transverter for 1296 MHz. I try to build a PA 45W this was not working. I start lock at ebay.com  an found a PA original from N9RIN. I by this and put it on a heatsink, it works grate. I run a few QSO with good reports. This pa was original set for class A bias 1.3A. My ide was to lower this to 400mA but when I try this I blow the transistor. It was a hard fight to get replacement for the PTF10021 infineon transistor. I bye 2 pcs from Alibaba, Kina this was not working. But on 18 December I received a pcs from Kynix.

 Perfect 23cm test was on the 19 December an now all was working even with lower bias 400mA, I measured 45.4 dBm out, not bad. The voltage to the PA is 28V so I tried to up converted it from 12V, there was a good article in Radcom nr2 2017, bayed from ebay.com, and add some filtering. Cant measuring any spurious on spectrum. A coax relay CX-140 used and a isolating extra relay Panasonic RK1-12. I has an already built RF pre-amplifier as I remember it is from  YU1AW, yu1aw. 

Now all is finished, before Christmas, hop on many more qso. next year.

PA and Driver for next QRP Transciver

I has built a driver for the PA. I started to lock at “Building a Transceiver” by EI9GQ and G4LFM. Side 118 it has a promising setup of RD06HHF1. The test showed god result. Next step was to put it together with the PA. I has little more to do with the optimize power transfer from driver to PA, but it will work just to optimize performance. In The plot from VNA it was 30dB atten from the output to VNA, its means gain in driver is close to 20dB.

PA For next QRP station

I by this PCB from K5BCQ a long time ago. Now I hade time to build and test the performance and it locks weary promising.  I measured max 42.7 dBm out.  But I think 42dBm 16W is more ok to not stretch the PA to much. The flatness is better then -0.7 dB from 1.8 – 52 MHz. It means that the work with the output transformers is grate.

I waiting for driver transistor to put in front of this module. I will put info here as son I has test the driver.

Link PA description K5BCQ