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 http://www.vectronics.com/Product.php?productid=VEC-101K

Shortwave converter for AM radio: https://books.google.com/books?id=rZDbnQ0siCYC&pg=PA307&lpg=PA307&dq=how+to++Intermediate+frequency+output+of+am+radio&source=bl&ots=sMJHJ1BecU&sig=QemPm07_g2Tyqk-SVrCD3CEAnpE&hl=en&sa=X&ei=pMsYVdeCH_i1sQTtp4L4DQ&ved=0CDYQ6AEwBTgU#v=onepage&q=how%20to%20%20Intermediate%20frequency%20output%20of%20am%20radio&f=false

40 meters to CB by vk3ye (includes BFO): https://www.youtube.com/watch?v=hCdt0aXj7bc

upconverters

kf7lze roundup of up converters: http://blog.kf7lze.net/2012/09/14/round-up-of-rtlsdr-upconverter-choices/

 

W9RAN Ranverter Pi: http://www.hayseedhamfest.com/ranverter_sdr_261668310.html

ct1ffu upconverter: http://www.ct1ffu.com/site/?option=com_content&view=article&id=178&Itemid=104

IF converters

455kHz -> AF Converter (DRM): http://users.belgacom.net/hamradio/schemas/DRM_455kHz_to_LF_Converter_FRG-100.htm

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!

RADI0KIT-2 DRM SSB RADIO BROADCASTS DECODER KIT / IF CONVERTER.

 

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: http://www.ebay.com/itm/Babel-Fish-IF-SDR-Radio-1st-IF-I-Q-software-conversion-module-/231292143562

A Binaural IQ Receiver by Rick Campbell: http://www.arrl.org/files/file/History/History%20of%20QST%20Volume%201%20-%20Technology/QS03-99-Campbell.pdf

QSD By Ray Ring: http://circuitsalad.com/2013/12/30/my-phasing-receiver-is-a-success/

Thomas Nylund Tayloe detector and SDR http://tuomasnylund.fi/drupal6/content/software-defined-radio

Softrock Lite II 06 mixer: http://www.wb5rvz.com/sdr/sr_lite_ii/06_mix.htm

Other

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

Download

https://github.com/tkzic/max-projects/

folder: rf-mixer

patches:

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

http://www.amazon.com/Tera-Grand-DisplayPort-Thunderbolt-Microsoft/dp/B006FKTR3U

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

http://www.amazon.com/gp/product/B002PXFJ2O

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

01502526_00

http://www.radioshack.com/rf-modulator/1502526.html#.VRXF67qHRbw

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

http://www.radioshack.com/matching-transformer/1501253.html#.VRXHHbqHRbw

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

references