Posts by PA0P

    someone was having a better result with the 1 watt board:


    Hi Richard,

    I have removed all shunt caps and things got a wee bit better. I then added 1p at the device in and out and now have about 9 dB gain at 2.4 GHz at 400mW.


    I may leave it this way for the moment but i think i will be taking a knife to the wider part of the lines on the input and output.


    Geoff GI0GDP




    So keep on trying!! Cor

    For the Spectrian driver board owners in this thread pointing to low output level, please note this rather simple mod to achieve over 30W at 2.4GHz.

    It comes from a message by VK4OE (remember the Aussies do use 2.4 as their normalcommunications band). Here a copy of the message:


    Hello Colin and other readers.


    I feel that I can't assist your problem any more than the help you've already received. But I wanted to add that I do have one of these amplifiers working perfectly well at 2403 MHz, the centre of amateur activity here in VK.


    However, I did go through the whole amplifier chain trying to find locations for solderable tabs ("snow flaking"), hoping to make it work better at this further-out-of-band frequency. The interesting thing is that I did find one sensitive/responsive point and it was between the final device and the output port, where the microstrip track takes a left hand turn - see attached 'image.


    At 2403 MHz, 10 mW input delivered 31 Watts output following this small addition.


    It was also interesting that there seems to be a layer of some plastic material everywhere which has to be melted away before the solder will 'take' - it makes the resulting soldered joint less than good looking!


    I wish you well with rising to your challenge!


    --Doug Friend, VK4OE.


    Success!!


    73 de Cor

    Hi Kurt,


    You are running behind the market. Pick your choice from already available solutions:


    F6BVA - 20W with MW7IC2725N, DIY project

    SG Lab - 20W with PA2400, readily built

    Rene PE1CMO - 20W with BLM2425, readily built

    Further options are: the 30W Spectrian driver board readily built with small mod to do, the Andrew MRF21045 modules with15-20W (with mod to do) and several other UMTS boards.


    For sure there will be more designs applicable.


    73 de Cor

    interesting PA 3 WATT I am preparing I wanted to know from Cor PA0P if possible have the schematic I wanted to do it and how much power should the module insert?

    73 de iw5bsf Roberto

    Hi Roberto,

    Schematic is very simple. As per datasheet do not drive more than 5 mW at the input (50 ohm), put 12 to 28 Volts on pins 2 and 3 depending on the output you want and output is at pin 4 (50 Ohm).

    See the photograph for the decoupling of the powerlines. Take several values of capacitors, I did 22pf, 5000pf and 100nf. Any series inductor from the junkbox will do.

    Take attention to get a good ground connection, remember it is 2.4GHz...

    Hi, do you have a part numer or seller?

    The only one i found, dont ship to Germany.

    If I do check at eBAY.com there are currently 11 suppliers, no delivery restrictions.

    you can choose from new or used. My supplier was from HongKong.

    Hello,

    Sorry to read about your bad experience.

    If you are looking for a low power PA maybe this can be an alternative, in case that you are willing to solder a little bit.

    The board is made very easy, however a solid ground between the module and board is required. I did use 35u copper foil under both.

    Gain of the module is 30dB with an output of over 3 Watt at 2.4GHz.

    And the cost is ridiculously low : 9 Dollar on eBay !!


    I added a 6dB attenuator at the input to avoid oversteering. My use is as a driver for a (Andrews) MRF21050 module.


    73 de Cor

    Hi Remco,


    Still work in progress, 3 items from China went missing and I need absolutely better weather to climb my roof (considering my age).

    But it is fun to watch all the approaches in the meantime.


    73 de Cor

    Dave,


    Have to apologize for not reading first the datasheet, considered it as a 'normal' TCXO. However looking at the unit-price (5 times that of my OCXO!!) there had to be a difference.


    After studying the sheet I see a drift of 2ppb per degree C, which still gives a drift of the 9750 MHz LO frequency of 195 Hz/degree.


    Taking into account long term stability, jitter and phase noise my preference stays with the SC-cut OCXO .


    Here is my system set-up:


    Dave,

    0.08 ppm equals a drift of more than 800 Hertz per degree Celsius....

    So not OK for CW and digital modes and trivial for SSB.


    To me it is important to know my frequency and by using one central OCXO reference in my shack, I can have my receive and transmit frequency exactly synchronised. No separate tuning/RIT necessary.


    The LNB LO signal is simply fed thru the coaxline, less work than the TCXO modification I guess.


    But it is everyone's own choice how to do it. That is clearly visible on this forum!


    73 de Cor

    Hi Dave,


    Thank you for your investigation and conclusion.


    Maybe the next step is to switch over to an external placed OCXO as reference oscillator with much lower drift and better phase noise.

    It has to be synchronised for one time against a GPS reference and if kept on 24/7 it will remain within a few Hertz accurate over months. This is how I do it.


    I guess that with this approach any currently suspicious wobbling LNB will become a "pro" LNB.


    73 de Cor

    There exists already a very complete LNB overview on the internet, including specs and board photographs.

    Look here please: http://www.pabr.org/radio/lnblineup/lnblineup.en.html


    Maybe we can use this file as a basis and expand it /refer to it with a spreadsheet showing links to specific product measurements and modification articles.


    There is very much information available, but it is hidden in forums, twitter and personal sites.


    Especially info about the improvement of stability by remote feeding the LNB with a rock-stable/low phase noise LO signal can be interesting for many OM's.


    73 de PA0P Cor