Posts by DL5CN

Hallo Ernst,

at least I agree with you :-). The Console levels do not show the real SNR but are rather comparable under the discussed circumstances. May be, Simon will find the motivation to implement another DSP-routines one day. Probably just like PowerSDR. It's level measurement works perfect.
In summary we are more than satisfied to have a program like the Console. All properties together give excellent satellite operation possibilities. Not to forget the Pluto. Who watched - as i did - over the last two years the deveplopment of this program has to bring a highly estimation to Simon.

By the way, a friend, DL4JAL, desinged an USB-Control-Unit with Audio in- and output, PTT-Switch and a generator for CW. More details can be found on his website. All the functions are summarized to one USB-Port, controlled by a PIC.

73
Andreas

Hallo Ernst,

thanks for your informations. Unfortunately the Console ist not the best instruments to do such tests. To compare SNRs of a specific station between stations at different locations, there are some more parameters which has to be kept comparable. The zoom value for example has an enormous influence on the level meter. When I do the test, you described, I find 35 dB peak of the idle carrier of the CW beacon. But we know, this is much to much. To get reliable results other level meters with other instruments have to be used.
The Console Level Meter is good for optimizing the own dish or LNB position. From former threads we know, the transponder signals will not override 20 dB SNR, also with larger dishes. If you can see the transponder noise floor clearly, your receiving system is ok. There is nothing left to do. SNRs of the stations you receive, depends on their transmit power only.
From my unimportant point of view, when turning a dish to the sat, the increase of the noise floor is a valid criteria to optimize position and checking the own receiver. And, this absolutely independent from other parameters. We talk about 3 KHz bandwith.
Please don't mind me, discussing it a bit controversly.

73
Andreas

Hallo Ernst,

interesting idea. Would you please give a short description of your equipment and method to make the results comparable.

Thanks
73
Andreas

Hallo Lucio,
thanks for the picture but this is not what I expect. I would like to see the filter curve (may be highlighted) in the display.

Here you see a part of a spectrum. The filter curve is gray.

In the IC705 spectrum there is just a white line, this is the carrier frequency.

73
Andreas

Hallo,

is there anyone outside who knows if the IC705 can show the filter curve in the Display. Just like the Console does. And many other SDRs do also. If not, this will prevent me to substitute the FT817. As far as I know, Icom doesn't like to show the filters in their radios. It's hard to understand. Probably an update will bring it. I do not ask, if a two tone signal is avalaible. Some lines code more and it is done.
Have fun, beside my questions

73
Andreas

Hallo,

here is the simplest radio ever, take a Pluto and the AMSAT-PA with integrated Preamplifier only. Don't worry, it's a quick and dirty test setup. All is running with 12V only a 5V switching regulator feeds the Pluto. The current limiter is for fearful oms.

Mount this closed to a dish, connect it to the PC via Ethernet. The linear 4 Watt from the amplifier are enough. With careful adjusting the equalizer and compression you get a pretty nice signal. The efficiency of the amplfier is remarkably good. The current consumption of the radio does not exceed 2,5 Amps at 12V. That means, it's good for portable purposes also.
Have fun and a nice Whitsuntide to everyone.

73
Andreas

Hi Chris,

thanks for introduction.

If you decide to change the oscillator, don't put it back to the original pads. It is much better to have a thermal isolation. I used a very small board just to solder four wires to the original place. There is a whole, closed to the solder pads. Stick the wires though to have the oscillator free hanging below the main print. Temperature influence of the main board is reduced. A little fan above the heat sources can be helpful too. Otherwise a "Leo" is much better of course.

For removing the original oscillator use two irons and some more tin around the chip. The lead free tin is horrible. Turn the irons to more heat and you will remove the Chip within seconds.

73
Andreas

Hallo,

it would be nice to know your name.
If the receiver is locked to the PSK-Beacon all is fine for receiving.
The only oscillator which has influence to the transmit frequency is the 40mc clock on the Pluto board. While transmitting the board warms up and the oscillator starts drifting. Either you change it to a better one or use Leo Bodnar GPSDO. A possible shift should be changed with XIT-function of the Console. Don't use any calibration.
When using the 500HZ-tone of the Console, you can compare the transmit and the received frequency to achive beating while adjusting XIT.
Have fun.
73
Andreas

Hallo,

is there anyone who measured an amplifier with the SZM2166? The gain is lower than expected. The datasheet shows three stages compared to the SZA244.
I would like to see some S21-Measurement and if possible an intermodulation spectrum.
Thanks
73
Andreas

Hallo 2E0ILY,

the Plutos input has a wide frequency range. The LNB receives unwanted signals which will be mixed with Plutos LO-harmonics into the intermediate frequency. Use a filter at 739 MHz. There are low pass filters available for this frequency too. They block signals from strong base station transmitters into TV-systems above 800 Mhz.
73
Andreas

It is fixed, the chip is from NXP, type MMG30271BT1.

Hallo,

is there any information about the first MMIC in the SG-Lab-PA V3? An om in the neighbourhood has some trouble and I'll try to help.
A type or a link to a datasheet is appreciated.
Thanks
73
Andreas

Hallo,

the above comment sounds strange a bit. If I want to buy a specific revision, I should get one. Otherwise it goes back. Mouser or digikey can sell any revision to customers who don't care.
Who placed the youngest order? Which version was delivered? Are there older versions in stock? By the way, there are different releases of CN0417 too. Revision C contains a temperature switch. It can be used as a PTT-circuit. 600mA continous current consumption are unacceptable. May be, a chinese version of an amplifier with a SIRENZA-MMIC SZA2044 is doing the same job. Less current, a bit more gain and a standby pin also.
Happy Easter

73
Andreas

Hallo Syed,
thanks for the information. Meanwhile I know, the step down regulators are TCS4615. This are Chinese components. I ordered some and hope it will bring the Pluto back to live.
73
Andreas

Hallo,
I need some help. I am looking for Information, data sheet or samples of SOT23-5 switching regulators. The SMD-Code is
JWF5J
It seems it is manufatured in Asia. Until now no substitute could be found. Every information about these Chips is highly appreciated. The regulators are feed with 5V. The output voltage can be adjusted by a resistor divider, I guess.

Thanks
73
Andreas

I think, this was not the question....

Hallo,

I did a quick drawing. This is an advice from DC6HL (thanks! ) given in a qso. I think this is of general interest.

All three paths meet at the coax. 25 MHz is feed with serial resonance circuits. They do DC-blocking also. The operating voltage is feed via another choke. It must have enough inductivity not to shortcut the 25 MHz. Some µHs should do this.

The coupling capacities for 739 MHz must be small enough, use 15pF or so. This is a little barrier for the 25 MHz.

15pF have approx 15 Ohm at 739 MHz and 425 at 25 MHz.

The bias choke in the LNB is to low in inductivity. Mount a SMD-Choke with enough current ability, 100mA or a bit more.

In the shack, do this in the same way. Excuse the quick drawing. No need to go back to school

73

Andreas

Hallo,
some time ago, I did a similar observation. Output much to low, about -30 dBm. One hint was a bad soldering at the output transformer.
I tried to transmit at lower frequencies and increased it. Finally the Pluto returned to normal operation. Don'l know the reason but it works.

73
Andreas

Hallo,

I had the chance to have a look at the intermodulation distortion of a "Chinese Pluto". It was disappointing a bit. Originals and LimeSDR Mini do much better.
Can anybody confirm this?
There is no idea where the reasons are. The Chips are the same. Power Supply, layout
Don't panic, we will go further.
73
Andreas

Hallo Achim,

I know the datasheet. But are there amateur constructions which confirm this really? Unfortunately nobody does IMD-Measurements. Between my small result and what the datasheet says is a difference. I would like to know where the mistake is. From my point of view, the chip seems to small for 27 Watts SSB-PEP. This means two carrriers with 38 dBm. Does the above diagram show what we call linear operation? More Spacing of the single carriers gives less dissipation. A two tone measurement with the usually small spacing signal from a Pluto or Lime would be appreciated.
73
Andreas

Hallo,

What is the difference between a WIKI and a FORUM? One have to read it otherwise it will not help. In a WIKI it is better structured probably. But the informations are the same nearly.
After some measurements and discussions about amplifiers, I think, first we need a paper about intermodulation distortion and how to reduce it in praxis. I often read and listen to informations about single carrier output. Without results about the linear operation range of an amplifier it has no releveance. In the past there were no easy to handle two tone signals. Now with digital systems it is simple.
73
Andreas