On Jul 4, 6:31*am, clifford wright wrote:
Good day!
Can anyone point me towards a good design for a good RF stage for my home
brew HF receiver. I have no less than 6 others hams in my small town and
one within 400 metres, so I need good strong signal performance.
10 to 15 dB gain would be ample, but I would like to have 50 Ohm input and
output impeadances.
The receiver is an upconverter to 45MHz with a 15 kHz bandwidth xtal filter
followed by a downconverting mixer to either 9MHz or 10.7 MHz with separate
IF strips.
Tuning is by a PA0KLT synthesiser.
I have been a bit out of touch lately and am not very up to date with the
latest MOSFETS etc. The mixers use the 1992 Ulrich Rohde FET double
balanced mixer circuit.
The rest of the sytem was built back in the early 1990's but put to one
side until a better frequency sythesiser was available.
Now it looks like the time to get things moving again!
Regards Cliff Wright ZL1BDA ex G3NIA
Hi Cliff,

Piero and Tom gave you good comments.

If you need a strong front end your problem is not in the rf
amplifier. You need a strong 1st and 2nd mixer and for this there is
no better solution than the H-Mode Mixer. Having a una upconversion
1st IF, your critical point will be the 2nd mixer that will receive
strong signal amplified by this stage..

If you look at PA3AKE web page you con find info regarding my
simplified version I7SWX 2T H-Mode Mixer (http://
martein.home.xs4all.nl/pa3ake/hmode/2t-hmode.html). This has only 2
transformers and homebrewed, not purchased. You will see the info on
transformers winding, the one with 5 windings may seem difficult but
is not. In low bands you may avoid to have a preamp. Look at the G3XJP
project Pic-A-Star (RSGB RadCom and also reported in the Handbook).

73

Gian
I7SWX

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