Browse DigiKey’s inventory of ATC B SeriesCeramic. Features, Specifications , Alternative Product, Product Training Modules, and Datasheets are all. B, to , Porcelain and Ceramic (NPO) 0 ±30, 10 , — — — , , –, — –, ATC RF/Microwave Capacitors QPL Approved to MIL-PRF/4 and 5. 2. A M E R I C A N T E C H N I C A L C E R A M I C S. w w w. a t c e r a m i c s. c o m.
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This page is the guide for assembling the previous version of the kit. The newer kit, with board rev 4d or higher, 700bb constructed differently, and the assembly guide for that page is located here:. After building 4 of these amplifiers without any issues, the 5th exhibited a low-frequency oscillation which caused an electrolytic bypass capacitor to detonate. One additional component L3, a 5nh inductor should be added across the gate pads as shown at the end of this document.
In fact, this component is shown in one of Freescale’s sample designs, and it’s purpose is now clear. My guess is that there are variations in devices from lot to lot, and I finally used one with a bit more low-frequency gain than the others.
Assembly Guide for the 1KW MHz Amplifier Kit
However, this inductor reduces the low frequency gain of the circuit without affecting the performance of the amplifier at MHz, and eliminated the instability completely. The space between the capacitors is small, be careful to avoid solder shorts that bridge this gap.
Verify that the bodies of the capacitor pairs are not shorted to one another. Note the polarity marking on the electrolytic capacitors Now connect the 12 ohm coax as shown in the second picture.
Form the coax as shown, and place it so it tilts toward the output end of the board a bit. This provides some spacing away from the electrolytic cans. Solder the shield to the left trace, and the center conductor to the right trace as shown.
American Technical Ceramics (ATC) B-
Your completed output board should look like this now. Check the two 50v power input traces for a short. Your ohmmeter will probably show the charging of the electrolytic capacitors at first, but then the traces should read open.
After checking, discharge the 50v traces to ground the ohmmeter will have charged up the electrolytic capacitors. Moving to the input board now, load the components shown. Trimmer capacitor – after placing the part, align the slot on the trimmer capacitor vertically this will place it mid-range.
I used a zero ohm chip resistor here, but a jumper of any sort will work. The extra pads are for additional chip resistors in the event 7000b the bias must be fed from a voltage higher than 12v not used here. Make and install L3 as shown at the end of the document Testing:.
Assembly Guide for the 1KW 222MHz LDMOS Amplifier Kit
Once you install the boards, and you are ready to test, here’s the recommended method:. Turn on the 50v main supply voltage, but not the bias; there should be no current drawn. Now turn on the bias and set the bias trimmer for 2 amps idling current. Drive with 1 watt or less. Tune the input trimmer cap for lowest input SWR or highest drain current. Increase drive until you have 1kw out. Input power should be less than 4w, and drain current less than 30A at 50v.
The shape and value of this part is not critical; it’s purpose is to ensure stability by reducing the low frequency gain of the circuit.