Showing posts with label transsceiver. Show all posts
Showing posts with label transsceiver. Show all posts

4 May 2013

The £20 DECENT HF transceiver challenge

Ideas for the £20 (or less) new HF transceiver so far, based on past experiences:
  • VXO controlled, single band- GQRP crystals are inexpensive, but will allow around 10-15kHz easy pulling on 14MHz, more on 21 or 28MHz.
  • Single balanced diode RX mixer - homebrew with low cost diode and toroid matching
  • 2N3904s everywhere - these low cost (5p or less), ubiquitous transistors work well as oscillators, PAs (if several paralleled up) and are OK in audio stages. Maybe an IRF510 PA if a lower HF band chosen,
  • Deadbug build - on  a small piece of copper laminate and low cost using a few MeSquares to help ease construction
  • Low cost metal box - e.g. Maplin Aluminium box or a diecast enclosure. A mint box would be less expensive but too small.
  • Few controls - a 1k pot for RF gain is all that's needed on RX
  • Capable of running from a PP3 9V supply or external 12v - rechargeable 9V packs are low cost from 7dayshop.  69p each non rechargeable and £2.60 for a rechargeable one.
  • Low-Z stereo headphones will be less expensive than a crystal earpiece these days - may need an extra audio stage but at around 10p for this, this is a price worth paying.
  • Probably CW, although DSB not out of the question.
  • No ICs at all - these are too expensive (maybe an NE602 might be cost effective and I'm not sure about a low cost IC for the RX audio).
  • TX-RX offset essential - so that listening on the actual TX frequency is possible
  • Does not have to be pretty - the aim is a transceiver that can be thrown in a rucksack and survive reasonable abuse levels.
  • Wire antenna - a simple dipole or end fed half wave.
  • At least 2W RF out, ideally 5W - so that the rig has a reasonably good chance of being heard on a busy band
Is anyone else up for this challenge? The target is a really credible HF transceiver with decent, not compromised, performance that can be made with all new parts for less than £20.

GQRP club sales offer some very good prices for components if you are a GQRP Club member. If you are not a member then you are missing out on the very best magazine (SPRAT) available. I cannot recommend SPRAT and the GQRP club highly enough.