EMRFD Message Archive 1166

Message Date From Subject
1166 2007-11-18 12:53:38 Kevin Purcell QRP2004 transceiver design online

> QRP2004 transceiver design available online
> G0BBL, G8BTR and M0PUB are delighted to announce the online
> publication of their 'QRP2004' HF Transceiver design.
> This fairly complex design has been in the pipeline for a long time
> now, but a full description is finally available at http://
> myweb.tiscali.co.uk/qrp2004/
> The QRP2004 was described and demonstrated at Rochdale QRP
> Convention a couple of years ago, and received a lot of interest at
> the time.
> Since then we have been talking to the RSGB about publishing it,
> but since it still hasn't happened, we have made it available on
> the internet instead.
> We hope it is of interest, particularly to the keen constructor.
> Vy 73,
> Alan, M0PUB

A quote from the web site:

> The QRP2004 is a major new multi-band HF Transceiver designed by
> G0BBL, G8BTR and M0PUB. The article was first submitted to the
> Radio Society of Great Britain (RSGB) in October 2005, passed
> technical review in May 2006 and was due to be published in
> "Radcom" magazine starting in October 2006. However, many months
> later we are still waiting, so we have elected to publish full
> details on the internet instead.
> To keep this site as simple as possible, the full article
> transcript is available as a single PDF file
Good idea to publish it on the web (where they will get a lot more
readers). But note they're naive enough to underestimate the demand
and put it up on a "free" ISP site that promptly gives a "too much
bandwidth" error.

There is a working mirror (at noon PDT 11/18) at


Why should you be interested? To quote the first couple of paragraphs
from their paper:

> The QRP2004 is an all-band Direct Conversion Transceiver aimed
> primarily at amateur use on the HF bands. It supports CW, LSB and
> USB modes on all HF amateur bands from 160m to 10m. It also offers
> general coverage receive capability, with continuous tuning from
> 132kHz to 30MHz with a 10Hz tuning resolution. As presented here,
> the design also offers
> optional support for the 6m band, but please note that this is
> still at an experimental stage, and at the moment 6m performance is
> relatively poor.
> Probably the single feature which sets the QRP2004 apart from other
> designs is its received audio quality, which has been widely
> praised by those that have heard it. However, it provides an all-
> round high standard of receive performance including excellent
> selectivity and good sensitivity. Although we have not been able to
> measure IP3 figures yet, the mixer and front-end design should
> ensure good performance in that respect too (we anticipate
> somewhere in the region of +20dBm, based on results from similar
> mixers).

The "mixer" is a Tayloe Product Detector (Quadrature Sampling
Detector) using QS3153 or FST3253 in singly balanced form. LO is a
DDS referenced PLL with two half-octave VHF VCOs divided down to
required frequency. Audio quadrature is a 7 section polyphase filter
after JA1KO. A number of KK7B's ideas reappear here. The PA is the
“QRP-PA” design from Peter Zenker, DL2FI using a 2SC1970/1 driver and
a pair of 2SC1971s to get 5W (160m) to 2.4W (10m) from 0dBm. With ALC
they get constant 5W out on all HF bands. A PIC provides rig control
and UI.

There are a lot of interesting ideas in this design (and lots of
useful advice).

You can see their earlier QRP2000 and QRP2001 at

Kevin Purcell