QRP Frontend 02

QRP Frontend 02

Final test with the Arduino Mega controlling the i2C buss(select Filter and set attenuator Tx/Rx, turn Rx amplifier on/off.

QRP Frontend 02 is a BP filter board with RX preamplifier MAR-6 or a discreet PIN-diode attenuator, controlled by a dac. The same BP filter and the attenuator is used in Tx and is driving a amplifier SGA-3486Z as driver for the QRP PA earlier described. All BP filter is controlled from I2C bus. BP filter is from YU1LM i i think it is rely good result, no alignment.

I has started working on a front panel board, the latest before putting all this together to a QRP Transceiver. Stay tuned!

QRP LP filter and SWR board

QRP LP filter and SWR board

Here is the LP-Filter mounted on the earlier described PA.

QRP LP-SWR 01 is a LP filter board 1.8MHz - 52MHz and added SWR Meter, all relay for filter is controlled from I2C bus. The filter is design from GQRP Club Datasheet W3NQN, Filter PDF. I have rely problem to get low insertion loss, so I think it was the toroid was the problem. Now I know it is the capacitor I firs used has really bad Q value. I has change to SMD GC0 500V capacitor and they has much higher Q value than the hole mounted capacitor I bayed first. The SWR was presented in QRP-Quarterly January 2018, SWR Meter. I lock for different diodes then 1N60 and tried a few types and get god result with HSMS2800. Her is the result. 

Exemple 80m and 10m.

Backside off the filter.

Part off shematic

I have a few PCB left, e-mail if you ar intrested xxx@gmail.com.

Signal generator for short wave 0.1 – 30 MHz

I have an old test set Schlumberger 4022 I don’t need longer. This was one reason to build this generator. The generator is a kit from QRP Labs   it uses Si5131 from Silicon Labs. I used 2 attenuator  Weinschel  0-63.75 dB. The insertion loss @ 0dB atten was around 7 dB so I need a Amplifier and one more attenuator to compensate for that. I adjusted the attenuator to get 10 dBm output. A high isolation switch on output to turn on/off RF, typical 75dB isolation. A rotary encoder and Arduino mini pro drive the attenuator and isolator directly and one I2c OLED display, really simple solution, sw 100 row of code.

RF Power Meter

It started with that the Anritsu power meter ML2438 brakes when i turn on the meter. The fault is in the power supply part. I lock around on internet and found this from Elektor.  link RF Power Meter

I ordered  the boards and build it. Get a problem with the software note a few liens in a forum and get a updated version in a few days. Added battery voltage reading on the display. It is really handy to only have one connection the RF port, that’s the reason I build in Lipo-battery 7,4V.

Data• RF power meter
• Bandwidth 1 MHz to 10 GHz
• Dynamic range 55 dB
• Compact: approx. 95 × 36 × 30 mm
It has 20 calibration points in frequency, so it is possibility to get accurate measuring result.