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Ameritron RCS-4 modifications

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Suite à une défectuosité du transfo d'alimentation, une grande partie des composants de mon switch d'antenne Ameritron à été détruite.

En outre des LEDS, toutes les diodes ont sauté ainsi que les relais de commutation ainsi que les électrolitiques.

Pas surprenant si on regarde le schéma du communtateur

Les modifications apportées sont les suivantes :

- Ne plus fournir de tension de commande des relais via le câble coaxial

- Eviter que ce 12V AC qui transite par ce même câble coaxial ne soit présent à l'entrée d'antenne du transceiver.

- Eviter deux polarités.

- Protéger les E/S coaxiales contre les surtensions dûes à la foudre

- Améliorer la longévité des bobines de relais

- Eviter une surtension de commande

Preselector 10Khz-600 Khz

Details: Hits: 4896

I have added this simple preselector to my RX. (from LF today - RSGB publications)

Advantages : parts are easy to find - it is easy to build - verry efficient to pick up little signal in a verry small bandpass.

Inconvenients :if you want monitoring a large bandpass with your SDR, the signals outside de BP of the filter are excluded : the best way is then to include a bypass position (use then a 6 position rotary swich), first bypass the whole preselector, pick the wanted signal , and then tune it using the other postions of the rotary switch.

2 Phased Verticals Array 40m

Details: Hits: 5737

I build last week a Bazooka vertical for the 40m (see link here) with good results.

This inspired me to build a second one and implement a two phased vertical array system.

I have chosen for a Christman phasing system : simple and easy o build

ON8IM Christman

Reception of DCF49 signals

Details: Hits: 4216

F(rx) = 139.000 Khz

Decoder : multipsk mode ASCII 8bits shift 200 Hz + IEC 870-5 decoding

BUT !!!

Decoding the frames is much better (merci ON4MS)

1/4 Vertical bazooka antenna for the 40m

Details: Hits: 18336

I needed a omnidirectional antenna for the 40m.

Here is the schema of the antenna :

on8im vertical 40m

Weather forecast on 147 Khz

Details: Hits: 4196

All infos here are coming from : http://weather.mailasail.com/Franks-Weather/Radio-Teletype-Weather-Broadcasts

In Western Europe and the Mediterranean, the Deutscher Wetterdienst (DWD), the German Weather Service have the responsibility to broadcast Weather information for mariners on RTTY.

Frequencies table see below :