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Thank you. Does anyone know if there is a real difference between the variants of the BS170? I just ordered BS170P mosfets. There were other variants, but I went with this one since it was actually

The TN0606 seems to have a much higher input capacitance than the BS170 and this may translate into slower switching and increased dissipation especially on higher frequencies . Hard to say if they

I have a QRPometer from NM0S. (It was originally a 4SQRP kit, and is now offered by its designer.) It is both a power meter and an SWR meter, and when used as an SWR meter has an absorptive

Hi, my QMX is running well at +12V. Had to repair the Q103/Q104 short issue first by moving a bit the bigger one. Fortunately I measured the short before using it. I went the assembly my way: -

A resistive bridge, NOT the transformer kind, has 6dB of insertion loss which absorbs much of the reflected power, so the VSWR the transmitter "sees" is ~1.5:1 or less, regardless of what the load is

Hi Chris, when my QMX was very unsensitive (-53 dBm) I found my mistake, I have cross wired the two?of three trifilar pairs?(B-C and C-B instead of B-B and C-C). When I repaired that I was

Jerry, you can’t send characters one at a time to the mini, that why you are seeing the ‘ reply. you have to put the whole command together and send it as a block. 73 Ken g4apb

I tried USB to RS232 on my QCX Mini and it didn't work for me. USB to TTL worked like a charm. Jim - W4BQP since 1953

What we observe is that the LIN_REG_EN line goes from floating high to being pulled to the 3.3V MCU high state which as far as the V_IN line is concerned is low.? Hans has done this in his setup

Besides having higher voltages, a USB to RS232 signal will be inverted compared with a RS232 TTL signal.

The US equivalent to the Kanga pocket trans match is EMTECH's ZM-2. 4SQRP has a similar tuner to QRP Guys and Pacific Antenna has some too. -- 73, Dan? NM3A

That's true, but it wasn't really the question, as I recall it. The question was about what made the lower voltage segment on the LIN_REG_EN line. Since I don't know the microprocessor, I can't

Yes, but typically modern processors have a variety of control methods that can be configured, one of which is an 'open collector' style where it only pulls the line low and leaves it to float high.

See my recent post here. Summary: Higher voltage is before the microprocessor comes on line. The lower voltage is after it's online and initialized, but not yet OK'd the switching power supply.

I did a poor job of stating my question. ?I agree with your assessment of the voltage regulator output. ?My question was about the LIN_REG_EN signal. ?If you look at the trace below, channel 2 is

Until the microprocessor comes up, LIN_REG_EN will be pulled up to +12 by R101. Once it's up and initialized, it will be fed by the microprocessor output from it's 3.3 volt supply. Does that fit

Nothing.? The Linear continues to produce 3.3V relative to it's 'GND' pin. if the supply produced by the SMPS is more then it provides nothing.? All this is confused by D102 andD103 which prevent

The QRPGuys SWR indicator uses an absorptive bridge in its design. I use it with my QMX. My problem is that I tend to band hop a lot and I often forget to switch it in for tuning. No problems yet, but

Evan's answer is correct but misleading because this is not the sort of SWR bridge that QMX has. QMX has a Stockton bridge and all it does is measure the forward and reflected power (or voltage?), By

I think there's some good argument (personal enrichment not least among them!) for using discrete parts. I like it, Hans! The thing I found difficult was that /both/ PS boards must be present (and