*** Prototype Special ***
|SMA Version||Large parts are used for easier first time building||BNC Version|
Want to try SMD for the first time but don’t want to try a big project with tiny parts?
This small QRP sized dummy load was designed as a learning tool for SMD soldering by using larger 2512 resistors for the dummy load portion. The 50 ohm load will operate from 500KHz to 30MHz with an SWR of less then 1.1:1 at power levels up to 20W under short durations. Usable at up to 225MHz with an SWR of less than 1.3:1. The circuit also includes a small tap for using an oscilloscope and a detector circuit for use with a DMM (or Arduino) to monitor your signal. The tap and detector parts of the circuit uses 1206 and SOT-23 type parts, which are one of the next common smaller sizes. We’ll leave 0805 and smaller parts to other projects 🙂
Available with either an SMA or BNC female connector.
This is a prototype run and a few changes needed to be made. We were not happy with the meter circuitry as it was too easy to pop the diode at full power. (It was not John-proof!) A few part changes and a small modification of an additional part between C1 and ground is needed. The part changes are included and can be seen in the pictures above – click to zoom in. For that reason we are selling these prototype kits at our cost!
Load Duration and Tap/Meter outputs
|1.000||30||7.07||0.707||1.000||1.110||Unlimited||100F at 30 seconds|
|2.500||34||11.20||1.120||1.700||1.830||>3 Minutes||HOT 140F at 30 seconds|
|4.000||36||14.10||1.398||2.150||2.250||>3 Minutes||HOT 160F at 30 seconds|
|6.000||38||17.50||1.770||2.610||2.850||120||HOT 180F at 30 seconds|
|10.000||40||22.40||2.250||3.400||3.670||90||Melts solder in 100 seconds|
|15.000||42||28.00||2.700||4.300||4.420||45||Melts solder in 60 seconds|
|20.000||43||31.60||3.040||4.910||5.000||20||Melts solder in 30 seconds|