pa0nhc VHF index

EN = read English version article NL = Nederlands

^{Last
update : 20180124}
144MHz ARDF direction finding receiver.
Optimal receiving properties :
144 - 145.4 MHz.
Very sensitive (0.22 uV AM)
Max input 12 mV.
Very good selectivity.
Power : 9V @ 20 mA max.
Most components wired, readily wound coils, or self wound coils on Neosid forms.
Cheap die cast ALU box.
See also the 80m version

Six versions of directional couplers with RF or DC output for 28 - 435 MHz.
Installed in a cheap steel enclosure.

Updated : 20180124

Coupler with RF output.

Old mask for DIY PCB.

Coupler with DC ouput.
New design for factory made PCB.

28 - 435 MHz wideband low-noise
hi-IP
preamp.

DIY PCB version 2003

New smaller PCB 2018

EN
NL

DIY VHF helix filters.
Very selective, low insertion loss.
One to four resonators.
Combinations with coax filters.
145MHz band pass and 160MHz reject.

Cheaply made from paint cans and copper wire.

145MHz ARDF / radio fox hunt Yagi antenna.

VERY EFFECTIVE and light
Proven design.

Horizontal plot of 3 el. version

Home build 145MHz repeater duplex filter, made from cheap PCB material and cheap 22mm copper water pipe.

(GW4AKZ and Dirk Rijnenberg constructed one). Republished 20130529

EN
NL

Full theory on (145MHz) cavity filters.
(After a pencil paper from G8AMG)

De oude techniek van de Rotterdamse repeaters
PI3RTD en PI2RTD (ca. 1995-2005)
20170302

First adjustment of the PCB duplex filter