The RF Power Meter 2 is a development based on the utility of RFPM1, but it shares nothing with the RFPM1, save using an AD8307 as the sense module. Design criteria The design criteria are: small, portable, battery powered; direct reading dB scale; flexibility for a range of adapters to measure power, current etc; local … Continue reading RF Power Meter 2 (RFPM2)
At Chinese AD8307 power measurement module #1 I documented the first phase of checkout of a low cost AD8307 module. There are two requirements for accurate power measurement: input impedance of the power meter must be very close to 50+j0Ω (say input VSWR<1.2); and then gain from the SMA terminals to the AD8307 input terminals … Continue reading Chinese AD8307 power measurement module #2
I purchased a ‘ready to use’ AD8307 RF power measurement module on eBay for a project to develop a HF common mode current meter sensor for use with the RFPM1 (Duffy 2014). Price was A$22 incl post. Above, the AD8307 module on a small PCB with shield enclosure. Note the prominent labeling DC-500MHz, but the … Continue reading Chinese AD8307 power measurement module #1
This article documents a field strength survey of an M40-1 short helical vertical on 40m. This test is more a feasibility study of the experimental method and apparatus than an absolute measure of the antenna. The antenna under test is described at AUT – MobileOne M40-1 40m helical. Field strength was measured using a small … Continue reading Field strength survey of an M40-1 short helical vertical on 40m
Much is written about ATU efficiency, about the need for them or not, and often in subjective terms like “lossy ATU”, and most of it lacking quantitative detail. The little quantitative detail is almost entirely for purely resistive loads… as if that is typical of real life conditions. The most common configuration used today is … Continue reading ATU efficiency
(Belrose 1998) described a mobile antenna system which, to his credit, the author validated its performance by making a series of field strength measurements and calculating radiation efficiency. It appears that Belrose has assumed the antenna is omni directional for ground wave, though he shows that for higher angle space wave it is not omni … Continue reading Belrose field strength measurements of his 80m mobile whip
Transmit performance of 2m hand held transceivers reported relative field strength measurements for some transceiver / antenna combinations. This article documents a more careful measurement of the absolute field strength of one combination, and application of that knowledge to the other results. Measurements of field strength were done with Lou Destefano’s (VK3AQZ) VK3AQZ RF power meter … Continue reading Transmit performance of 2m hand held transceivers – absolute gain estimates
This article documents measurements of transmit performance of three hand held 2m radio with several antennas. Measurements of field strength were done with Lou Destefano’s (VK3AQZ) VK3AQZ RF power meter (RFPM1) and a small loop antenna. Above, the field strength meter, a RFPM1 with small loop antenna oriented for max gain in the direction of the … Continue reading Transmit performance of 2m hand held transceivers
My recent article Near-field field strength measurements using the RFPM1 described a technique using VK3AQZ’s RF Power Meter which is based on the AD8307 log detector. There are many ways to measure low level RF power or voltage, and this article describes methods that I have used using a simple diode detector attached to the … Continue reading Near-field field strength measurements using a diode detector