Discussion in 'Amplitude Modulation - AM Fans' started by N2DTS, May 15, 2018.
Ah, power supply plus tuner makes it a bit more understandable!
It's really easy to modify the detector box's circuitry to detect lower powers. Simply change the value of Rattn.
See the File below:
Older hollow-state transmitters had a built-in rf tank cincuit that came with the rig. Usually either link-coupled or pi-network. With modern solid state rigs, the tank circuit most likely comes as an optional outboard unit that costs extra. It's called a 'transmatch' or 'tuner'.
If you get a good enough match at the station end of the transmission line, you can get by without the output tuned circuit, but watch out for harmonics and other forms of distortion and spurs, since there is no flywheel effect between the output device(s) and the antenna to help clean up the signal.
I think the elad stuff is very clean.
They all have band pass filters, but the solid state output devices want to see a non reactive 50 ohms, they don,t like high voltage.
My antenna's are ok on 80 and 40, not all other bands have a low swr at the moment.
And yes, the REA sampler is easy to modify, but I can also hit it with 600 watts carrier from the big rig.
I usually run between 200 and 400 watts carrier so the elad at 3 watts falls outside the norm.
Checked the low end respnse of the standalone duo on RX and it goes down to at least 40 Hz.
I just transmitted and tapped on the mic base and boosting/cutting 40 Hz is audable, but 30 Hz is not.
Thinking about getting the duo art 120 watt amp with built in power supply and antenna tuna.
That will up my power from 3 watts carrier to 25 watts carrier.
How many DB is that?
7x the power...
Having some fun playing with receivers in the shack.
I have the Elad fdm duo, the Anan 200 B, the sdr-iq, and the homebrew receivers.
I run the elad fdm-sw2 software with the duo, and also listen right out of that radio, and I run powerSDRmRXps on the Anan, and I have HDSDR and SDR console for the sdr-iq.
SDR console has three differnet versions, all quite different, I like the simple early version 1.5 as its simple and has all the buttons you need on the screen.
For AM, it has AM, sync AM, and ECSS which allows a quick change between usb, lsb or dsb AM reception, plus it has a nice looking analog S meter.
There is some latency using the Elad software (very little in the radio itself) and the SDR-iq uses usb also and has latency.
The Anan uses ethernet and has very low latency.
I tried weak signal performance on 80, 40 20 and 10 meters between all the sdr-s and any difference is undetectable by me.
AM and ssb, weak signal, strong signal, fidelity, all very close, the Duo cuts off the lows at about 50 Hz, the software programs allow a response
down to 10 Hz or lower (if you want).
The SDR-IQ is usb and does 100 Hz to 30 MHz, the one I have now I got for $150.00, its a 14 bit unit, very well made, usb interface and usb powered.
The Anan 200B is a 14 bit 100 watt tranciever using ethernet.
The Duo is a 16 bit 10 watt tranciever, very well made, standalone is nice, usb ports add latancy when used with software.
On receive, none of the radios are poor, as a matter of fact, they all seem to be VERY good.
Each program has its good and bad points, and bad depends on what you like/want.
I like powerSDR and sdr-console version 1.5, version 2 and 3 are too complex and hide things in menu's for my taste.
Here is version 1.5:
Band buttons on screen, analog meter, mode buttons on screen, easy to tune, nice display.
All these radios and programs are fun to play with, and there are even more programs out there.
All the radios and programs can do real hi fidelity, 0 to 20 KHz with low distortion, feed it into a good amplifier and speaker for great sound.
The dongles are not as good, they are 8 to 12 bit units that overload easy, don't have filtering and preamps, but can work well for the price.
Another note, for those wanting a lower cost but low latency sdr rx, the Anan 10E is ethernet based and has a direct audio output from the radio like all the other Anan's.
With the latest software and an average computer, delay is about 50 milliseconds?, maybe less, very low.
If you don't mind the delay (maybe 200 to 400 milliseconds?) the sdr-iq seems like the best deal, it has band pass filters and is less erratic then the dongles, its not erratic at all.
The latency (delay) is only a problem if you want really fast break in or monitor your own signal (audio) using the receiver.
It works with a LOT of programs, its got attenuators and a preamp.
The older Flex 3000 and 5000 radios are good receivers, although maybe not quite as good as the direct sampling receivers out today.
The Elad fdm duo is good, its a 16 bit (every bit helps) direct sample qrp rig in a very small package that allows standalone use with limited functionality
and full sdr reception over a usb port that works well.
Transmitting using the software is a problem, digital modes might be ok but the software is made for RX mostly.
For AM use on HF, ALL of the radios work very well and about the same as far as filtering and fidelity go, and they all sound fantastic as far as I can tell.
Its nice to SEE what is going on around, where and what signals are/look like, your own TX signal (on frequency, width).
You can also hook one up to the IF on any vintage receiver and get most of the features of the sdr.
You can also bridge one on the antenna port and run both.
Just when this great sdr thing happens, HF radio seems to be going away, both ham and sw broadcast....
Thanks for the detailed review Brett.
Here is HDSDR:
Here is the Elad FDM software:
And here is the (bland) SDR console Version 2:
With most of these programs you can put more on the screen, audio spectrum scopes, other receivers, memory stuff, etc.