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Amateur radio RF power amplifiers
These pages contains various information about several RF power amplifiers, mainly for the HF bands, that I have built and characterized.
Most of the measurement were done with the automated system described in the automated IMD measurements page, so a standard set of data is usually shown:
- Power output (fundamental and first harmonics) vs. single-tone input power - for a fixed frequency, usually near midband
- Output power and input total supply current versus input power - for a fixed frequency, usually near midband. From these data also the overall PA efficiency is computed.
- IMD products relative power (for the 3rd-, 5th- and 7th-order usually) vs. input RF power - using a 1 kHz tone spacing
- IMD products relative power (3rd- and 5th-order) vs. tone spacing. Any asymmetry between the upper and lower IMD products is likely due to memory effects caused by reactive baseband impedances or thermal effects in the active device.
Here is a list of the amplifiers characterized so far:
A 20 W HF power amplifier
Measurements on an experimental 20 W HF PA for the HF bands using inexpensive modern RF devices.
HF QRP power amplifier
Measurements on the QRP Project PA-2008, a 5 W amplifier for the HF bands.
DL2EWN 5 W wideband PA
Measurements on a wideband 5 watt amplifier, designed by DL2EWN.
DL2EWN 1 W wideband PA
Measurements on a wideband 1 watt amplifier, designed by DL2EWN.
Wideband low-power amplifier
A small power amplifier for the HF and VHF bands using a PD85004 LDMOS in class A.
Wideband push-pull low-power amplifier
Another small power amplifier for the HF band using two PD85004 LDMOS in push-pull (class AB).
HF/50 MHz Class A PA
A Class-A simple QRP power amplifier covering the HF and the 50 MHz band, designed by Jim Veatch, WA2EUJ.
Small HF PA drivers
These drivers were intended to drive an HF PA for the Hermes-Lite but could of course be used for others low-power PAs. They cover the HF bands and have an output power of about 20 dBm.
All circuit use an ubiquitous 2N2222A (or its SMD version PZT2222A) and draw about 40 mA at 12 V.
Small HF driver #1
A classical resistive-feedback amplifier with 10 dB gain, 33 mW (15 dBm) output at 1 dB of compression. With a two-tone input, the output is 9 mW per tone for an IM3 of -30 dBc.
Small HF driver #2
Another classic, a lossless-feedback scheme by Norton; 9 dB gain, 200 mW (23 dBm) output at 1 dB of compression. With a two-tone input, the output is 61 mW per tone for an IM3 of -30 dBc.
Small HF driver #3
Another resistive-feedback amplifier, 10 dB gain, 100 mW (20 dBm) output at 1 dB of compression. With a two-tone input, the output is 27 mW per tone for an IM3 of -30 dBc.
Small HF driver #4
A resistive- and transformer-feedback topology by Rohde, 11 dB gain, 160 mW (22 dBm) output at 1 dB of compression. With a two-tone input, the output is 40 mW per tone for an IM3 of -30 dBc.
Small HF driver #5
Similar to the driver #3 but with higher gain (14 dB), 180 mW (22.7 dBm) output at 1 dB of compression. With a two-tone input, an IM3 of -30 dBc is reached at 50 mW per tone,
Small HF driver #6
Another variation of the classic resistive-feedback amplifier, with 15.5 dB of gain and 180 mW (22.7 dBm) output at 1 dB of compression. With a two-tone input, the output is 50 mW per tone for an IM3 of -30 dBc.
This circuit has ben built in two variants, one with a 2N2222A and the other with the more modern 2SC5551A, which gives a higher bandwidth (with otherwise similar performances).
BS170 PA
The final stage only of the Softrock Ensemble RXTX, using a couple of cheap BS170.