Month: March 2015

RF converter circuits

Notes and links.

down converters (shortwave to medium wave)

HF to CB/AM Broadcast Receive Converter kit, great for QRP!

Vectronics VEC-101k

Shortwave converter for AM radio:

40 meters to CB by vk3ye (includes BFO):


kf7lze roundup of up converters:


W9RAN Ranverter Pi:

ct1ffu upconverter:

IF converters

455kHz -> AF Converter (DRM):

Any SDR that will receive 455 KHz (or whatever the IF is) plus a R-Pi would work. The Pi would need to  boot automatically into an SDR app with the frequency set to the IF.

455 kHz BFO Kit – Receive ssb and cw on an am receiver!



IQ converters and panadapters

FST3253 is a commonly used chip for Tayloe mixers.

Babel Fish IF SDR Radio 1st IF I /Q software conversion module:

A Binaural IQ Receiver by Rick Campbell:

QSD By Ray Ring:

Thomas Nylund Tayloe detector and SDR

Softrock Lite II 06 mixer:


1KHz to 33MHz Adjustable Oscillator Module, LTC1799

RF mixer simulation in Max

Audio simulation of an RF circuit.

Screen Shot 2015-03-29 at 4.49.36 PM

The simulation serves no purpose, but its fun. There are 4 versions. I think the third one sounds best (rf-mixer-sim3.maxpat). Its interesting to hear how much spectral distortion happens from multiplying sawtooth waves.

Screen Shot 2015-03-29 at 4.46.55 PM


folder: rf-mixer


Note: please set the signal vector size to 1 (or as low as possible) and enable overdrive and audio interrupt

Screen Shot 2015-03-29 at 5.22.30 PM

Four versions:

  • rf-mixer-sim.maxpat (initial attempt)
  • rf-mixer-sim2.maxpat (uses sah~ and rate~ objects)
  • rf-mixer-sim3.maxpat (uses gate~ objects with a phasor~ clock)
  • rf-mixer-sim4.maxpat (bandpass filter on RF input)


Macbook analog TV mirroring

How to connect a new computer to an old Television

Signal path

Connect a VGA adapter to the Macbook DVI (Thunderbolt) port.

Screen Shot 2015-03-27 at 4.59.58 PM

Connect a VGA cable from the adapter to a PC-to-TV adapter. This converts VGA to video component (RCA plug) output. The sound from the Macbook can go through this adapter as well – it gets passed through to the RF modulator.

Screen Shot 2015-03-27 at 5.02.22 PM

Connect the PC-to-TV adapter, using RCA cables, to an RF modulator.


Connect a coaxial cable from the modulator to an RF transformer (75 to 300 ohms)

Screen Shot 2015-03-27 at 5.10.10 PM

Connect the 300 ohm leads of the matching transformer to the antenna input terminals of the TV.