Posts by PA3FYM

  • Octagon Oslo PLL LNB with external Reference

    @Michel OH2AUE just curious, in your beautiful

    detailed photo you removed the 27 MHz crystal.


    Did you try your 'BPF mod' with the crystal in place?

    The reason for asking is that some publications

    claim that removing the crystal is not necessary,

    however they inject the external reference not

    into the feedline and use an additional cable/connector,

    or sacrifice one halve of a 'two-connector LNB'.

  • 'The frequency'

    I don't think each OM has his own uplink QRG (the uplink

    frequency = 2400 MHz) but I fully agree, the downlink

    frequency makes the most sense.

  • 'The frequency'

    I spoke with an Es'hailSat technician at IBC2018 and

    told him I consider the payload of his company's

    (to be launched) satellite with impact in/on

    amateur frequency allocations as a 'normal' amateur

    band. That is, despite different up- and downlink

    frequencies, for me it's a 'transparent' bird in the sky

    (with with some delay and technical efforts).


    Identical to 50 MHz in the late '80's or mid '90's, where

    most countries had allocated around 200 kHz.

    The NB transponder bandwidth is 250 kHz <-- similar.


    Like on most VHF/UHF/microwave bands, I reckon people

    want to collect 'squares' (locators), so I forecast

    there will be an incentive to work 'DX(-entities)' or

    'rare squares'.


    Suppose I worked I1/DB2OS from JN43 (a rare square) or
    ZP/PT9KK (in GG27) as new DXCC and 'grid', and want to

    inform the community via/by the DX-cluster ... what to

    enter as 'the frequency' ?


    Several perspectives / 'points of view' apply:

    1. the IF-frequency (e.g. 14x.170 or 43x.170 MHz)


    2. the transmit/uplink frequency (e.g.) 2400.170 MHz


    3. the downlink frequency (e.g.) 10489.670 MHz


    Ad 1. personally I think it's useless to enter your

    IF-frequency as 'the frequency'


    Ad 2. this is where you create your spectral impact
    and 'for reasons beyond your control' it's relayed

    8089.5 MHz higher


    Ad 3. the 'receive frequency' is reported (although
    there you do not generate spectral impact yourself)


    So, what is wisdom?

  • Es'hail-2 transverter PA3FYM-approach

    The attached photo also was posted on Twitter, but I thought it would be a nice one as first posting in this part of this forum!

    The transverter depicted below is designed as a real 'BUC' (block up converter) to be positioned near a (multiband) feed.

    It uses 432 (or another IF) MHz as IF and is built with 'standard' (Ebay-like) building blocks.

    In transmit mode the LO (ADF4351) produces 1968 MHz, is amplified (SPF5189z) and fed to a HMC213 mixer. The wanted RF sideband is filtered with a small ceramic 'WiFi like' block, amplified with a TQP3M9009 and after some

    damping fed to a surplus UMTS HPA.

    With some fiddling I managed to get >10W O/P on 2400 MHz.

    During reception the same LO produces 307.5 MHz, which is fed to a ADE-1 passive mixer. From a GPS-locked PLL LNB (e.g. Octagon 27 MHz, or Starcom 25 MHz) the first IF (739.5 MHz) is fed to the ADE-1 mixer.

    After the mixer IF port a J310 provides 'firm' 50 Ohm termination (and somewhat gain, but this is neglectable).

    On the photo the LNB GPS-reference is not showed, but it lies here in my work bench ; -) The reference is made from a surplus Jupiter GPS receiver (with 10 kHz reference), an

    ADF4001 (PLL) and a low noise VCO. All power supplies in the reference circuitry are heavily filtered ('capacitance multiplification' i.e. emitter followers with large capacitance from the basis to ground).


    Both ADF4351 and ADF4001 are programmed by one ATTiny13a.


    Yes, the setup is designed as 'simplex'.
    Power supply, IF (RX and TX) as well as 'PTT' is fed through one (thick) coax cable.