RTC07S (super low cost) Si5351 Transceiver Controller

This low cost version transceiver controller designed for minimalist or simple mono-bander transceiver. We just have to connect the jumper pin to do calibration setting, if setting and BFO setting (if we used the BFO out) then, connect one or two frequency out to the exciter

*. 8 Digit 7 segment
*. ATMega16 controller
*. Si5351 synthesizer (LO & BFO)
*. VFO frequency out (0.1 – 99 Mhz) seven segment digit limitation, not the chips
*. Adjustable IF/BFO frequency setting
*. USB-LSB-AM mode control pin out.
*. 2 push button (mode and setting)
*. 1 ADC input 0-2.56V for s-meter
*. 1 DI/O for RX/TX
*. 3 DI/O for mode (USB/LSB/AM) out control
*. 7 LED Smeter indicator

*. you can buy this item on our web
*. https://hambuilder.com U$17
*. https://tokopedia/jalapindai Rp. 185.000





Hambuilder Team


New HBR4HF released

New HBR4HF is a compact 4 Band HF transceiver.
This simple and low cost radio is also suitable for entry level HAM to start do communication on HF band.

*. Assembed unit, tested and ready to use.
*. New 2.2 Inch TFT display,
*. 4 amateur band (80m, 40m, 30m sharing filter with 20m)
*. TX covering 80m/40m/30m/20m,
*. RX covering 3.5-14.5 MHz,
*. Step 1Hz, 10Hz,100Hz,1KHz,100KHz,
*. Output 13.8V 45-50W,
*. CW SSB modulation with 700Hz tone,
*. Display VFO A/B, mode, Smeter, Band, RX/TX.
*. IF Freq 11.059.200.

Band Coverage (programmable) :
80m (3.500.000 – 4.000.000)
40m (6.000.000 – 7.250.000)
30m (10.100.000 – 11.500.000)
20m (14.000.000 – 14.349.999)

*. Exciter complete set
*. DC chord
*. Condenser Microphone

store link New Hambuilder HBR4HF



Hambuilder Team

Hambuilder booth at “Bandoeng – Netherlands” Amateur Radio Fair 2018 (23rd-25th March)

Thank you for visiting our booth and spending time to review our product on “Bandoeng – Netherlands” Amateur Radio Fair 2018 (23rd-25th March)


Thank you for visiting us and making your first purchase! We’re glad that you found what you were looking for. It is our goal that you are always happy with what you bought from us, so please let us know if your buying experience was anything short of excellent. We look forward to seeing you again on next Hamfest.

Hambuilder Team

HBR10HF new board design with ADE-1 as RF mixer

Specification :
*. BRITX Based
*. Front End RF gain using 2SC2570
*. Front End RF attenuator
*. TX RF attenuator
*. ADE-1 main mixer (detachable)
*. Detachable ladder filter
*. CW generator/Key PTT delay on board
*. AGC on board
*. Band Pass Filter on board

By replacing main mixer with ADE-1 we can get very good carrier suppression, increase sensitivity, and we can get more TX power on almost band. We also added crystal ladder filter adapter, so it can be upgrade next.  You can replace the crystal with your mechanical filter (please take note the impedance matcing), or you can make variable BW filter by using varicap diode.

We decided to use separate RF amplifier board with LPF on it. We hope we can increase the power out, but still using the low cost MOSFET.

Dian Kurniawan

HBR10HF intermittent blank or gray/white LCD on start problem solving

Hambuilder HBR10HF using RTC03 as controller with 3.2 (320×480) TFT LCD. This item worked very nice, good color,  viewing angle, speed (using 16 bit parallel data). But the main problem is the availability is a night mare. I using this TFT since early 2016 when I started to build the RTC03.  Until now, this TFT already have 3 difference controller in market, with 3 difference firmware and specification and the worst is, seller from China that I bought this TFT did not know and did not help what kind controller or even give me any datasheet. I must find out by my self how to make this LCD works.

its look same but they have difference

when you look at their back side its HX8357C, V2.0 and blank, its all false
The HX8357C using ILI9481, the V2.0 using HX8357D and the blank one using HX8357C.
They need difference firmware and have difference command, and what I want to tell here is they have difference habit and speed. The blank one do not need hardware reset, but the other one intermittent required. This habit make your RTC03 sometime show the white or gray or even blank display on start.

How to solved this problem? actually is very easy (this bug already solved on our production line), please check the image below. We just need to added R-C reset delay. please see the picture below

and implemended like this on your RTC03, I choose R 10K and C 100nF.

Then if you get your RTC03 with intermittent gray or white screen on start you can applied this solution.

Best Regards
Hambuilder team

HBRAA3 progress, filter response plotter feature.

After a long rest, its get back

One feature on HBRAA3 Antenna analyzer is a filter response plotter.
Its worked based on
*. Si5351 as freq synthesizer
*. AD8307 logarithmic amplifier

by generate some range of frequency , send it to input port of a filter, then let AD8307 amplify the output port, then read the value (25mV /dB) by using micro controller ADC, we can draw the response on LCD.  This feature very help for analyze crystal ladder filter, BPF and LPF of any transceiver.

an example 10MHz ladder filter plot response (non scale)

Dian Kurniawan

HBR4HF (RTC01C + BritX tranceiver) tunning

Similar condition with HBR10HF some buyer report carrier leakage on HBR4HF, same proble with his brother HBR10HF, BFO level is too big injected to modulator. Here’s the solution :

*. Replace BFO coupling from RTC01C with 100pf value
*. Tunning the preamp trimpot
*. Tunning the carrier balance
*. Adjust gate bias voltage (Vgate) into 3V






How ever please take note, power of the transceiver considering many thing not just increasing the final stage value. We must consider also the cabling, switch relay, PCB track and etc. HBR4HF and HBR10HF not designed to produce big power.

Hambuilder team