QO-100 setup with AMSAT-DL parts, will this work?

  • I guess it will be either small dish with no attenuator or big dish with possibly an attenuator. I will try a big dish first, so we will see. ;)

    Robert - PC5E / AC2E / SP20EJ

    Icom IC7300, Icom IC7000, Anytone D578UV, Anytone D878UV

  • Hi Robert. You may want to double check the AD amplifier after the Pluto. I'm not sure it has enough gain at 2.4G to generate 500mW output from a Pluto. Also, the max output from the Pluto could be lower than +7dBm. The Lime has an even lower output.
    Another option would be to use the new version of the SG Labs amplifier which needs 40mW for 20W output.
    Better to need a small attenuator, rather than be 4 or 5dB short of signal.


    Thanks es GL


    David

  • David G0MRF , I used the specs from the Pluto and PA's for the link budget calculation. Not tested in use yet. ;) I also did not calculate the loss of the connectors and pigtail.


    And a new SG Labs PA? Do you have a link to it? That sounds interesting! Attenuation is indeed simpler than ampification.


    Thanks!

    Robert - PC5E / AC2E / SP20EJ

    Icom IC7300, Icom IC7000, Anytone D578UV, Anytone D878UV

  • HB9SKA , unfortunately the AMSAT-DL shop does not carry equipment other than for transverter use... I would gladly shop there, but I cannot build a full-duplex set with transvertes within budget... :(


    And thanks for the link to the v3 PA, now I just need to get the Pluto output to 40mW (or add an attenuator between the first PA and the SG Labs).

    Robert - PC5E / AC2E / SP20EJ

    Icom IC7300, Icom IC7000, Anytone D578UV, Anytone D878UV

  • HB9SKA : mMy IC7300 and IC7000 are not full duplex, unfortunately. So a transverter solution @10m will not help... But their 2400MHz PA also looks interresting!


    G0MJW , hmmm... That is an idea I had not thought about, using the cable losses as attenuation.

    Robert - PC5E / AC2E / SP20EJ

    Icom IC7300, Icom IC7000, Anytone D578UV, Anytone D878UV

  • Hello Robert, I use the Pluto with the Pre-PA from AD. That match to the Pluto and I order both together. It is the CN0417 from AD. I ordered in US and get it within 4 days and relative cheap. This PA have already filter for 2,4Ghz and bring the Pluto to a level of about 100mW around 20-21dBm (that is what I measure). From that you can drive the SG-Lab PA V3 as this need just 40mW, so just one small attenuator. I ordered the new PA and will test when received.


    73,Oliver

  • DO1OHB , thanks for your message! Like to hear what you need to use as an attenuator to get the v3 PA not overloading and what power out you get. The v3 should be able to handle 50mW in (for 22W out), so it should about 3dB attenuation.


    Your setup sound a lot like what I am planning!

    Robert - PC5E / AC2E / SP20EJ

    Icom IC7300, Icom IC7000, Anytone D578UV, Anytone D878UV

  • PC5E, Robert, I guess I will start with a 6dBm attenuator as the power is much as sufficient even with 24V (that is the voltage I use). Then I am on the safe side, 2dBm more or less will not make a huge different (in that range) but could set the PA at risk. I guess with 40mW input you need to be carefull.......


    73, Oliver

  • Hello Robert,

    your set-up plan looks nice. I have basically have/will have the same, so allow me some comments:

    1. RF band pass filter is always a good item but the CN0417 have one inside so it would be better to have a band-pass behind the last PA (but then you need a stronger one) - I have the same point and not sure how to fix.

    2. Power Management. The PA (with the highest power consumption) require 24V-28V. So my idea was the other way around. Meanwell 24V-90 Watt external Power supply (MW GST90A24) with two DC-DC buck converter (DEBO DCDC 25W) . One for 5V (as they are adjustable I go to 6,7V and then on a 5V voltage regulator (5A) LM 1084 IT5,0 to be sure that the DC-DC have 100% the right voltage and not higher voltage on the start). The second DC-DC for the BIAS 12/14/18V as required. Actually I have another Pre-PA EP-AB003 for 12V - will not need it with the new SG-PA V3. The DC-DC converter have a low load guess 1A for 5V and 0,5 A for 12V, so they stay cool.

    3. I guess you will need a frequency-stabilization for the Pluto (either TXCO exchange inside the Pluto) or external GPSDO. I will go with the GPSDO (another 5V for the DC-DC). This stable frequency could be used also for the LNB. Actually I am looking how to bring this frequency to the LNB cable (one cable solution like AMSAT-downconverter).

    4. The new SG-Lab PA V3 require only 40mW input (max 100mW) so you need an attenuator between CN0417 and PA (guess -6dB). I will get the PA in the next weeks and start with 6dBm, 3-5dBm for maximum output. As the PA have enough power (15W), also with 24V, it will not be an issue.

    That are my ideas around your question.


    73, Oliver

  • 1. RF band pass filter is always a good item but the CN0417 have one inside so it would be better to have a band-pass behind the last PA (but then you need a stronger one) - I have the same point and not sure how to fix.

    Just one remark on the filtering in general: a bandpass filter is required to get rid of any spurious emissions of the SDR (and there are plenty). You can (and should, see later) add this at a low power stage. Follow-up stages will then only generate additional emissions because of their non-linearity. Driving them -3dB (or even -6dB) from max helps a lot but even when driven hard, a normal bandpass will not help you here. The IM3 (3rd order intermodulation) will be directly next to the signal itself, so it will pass though the filter anyways. Another possible additional generated emission would be the 1st harmonic (at 4.8 GHz) but as the TX feed will likely have little to no matching there the amount of radiated power on 4.8 GHz will be low. This can easily be fixed with a lowpass if required and these are much more easy to build for higher power levels.

    The best 13cm bandpasses for hamradio (as far as know) are the interdigital filters made by DK2DB (check his shop) based on a design by my old man DL3NQ in the 1970s. They are rather big (ca. 30cm) and can handle a few dozen W of power but have a BW of 25MHz. So Q-factor of ca. 100 but unsuitable for removing IM3 of course..

  • The best 13cm bandpasses for hamradio (as far as know) are the interdigital filters made by DK2DB (check his shop)

    Wow that DK2DB-solution is rock solid and the measurements are impressive too.


    Out of the information above you strongly recommend a band path also between SDR and the CN0417 (first pre-amp). Got it. Thx.


    73, Oliver

  • Hi Oliver,

    actually if it weren't for the aluminium of the DK2DB filter, you can use it as a hammer.. it is big, heavy and well made. These type of filters (as duplexer variant) were used in many Packet Radio interlinks in DL (those were the times..).

    CN0417: this one (and the G0MRF SDR driver amplifier) have integrated bandpass filters, so no additional filtering required. See a plot from the CN0417 datasheet here:



    I would guess the bandpass from G0MRF looks similar as they are both SAW type filters.

    73s Achim

  • DO1OHB , I chose to step up from 12v because I want to be able to use the setup off-grid if needed. With 12v I can easily use my car battery as power supply.


    Now if only I could buy a already TCXO-modded Pluto... To do the TCXO mod myself I need better eye-sight, better hand-stability and better soldering equipment. :( The equipment can be bought, but the rest not...

    Robert - PC5E / AC2E / SP20EJ

    Icom IC7300, Icom IC7000, Anytone D578UV, Anytone D878UV

  • PC5E , the 12V from the car battery is a good argument, when I will be on tour I will use the 220V from my mobile-home ;-) . So yes, requirements are key and could be very different.


    Regarding the TCXO-Mod, I bought a lamp with 90leds and a 2,5x lens. Even then it would be a tough challenge. I installed the TX-Mod on the Pre-PA (EP-AB003 WIFI), just a little bridge between two chip contacts. It worked but I realize that I get older ;-).

    I saw some Plutos with TCXO mod on ebay but relative expensive so I decide to take a risk and challenge.