The Ilmari Project is not a Viestikallio Project, this just happened to be a place where we could host these web-pages...

SUPER ILMARI lab session n:ro 5: 2003-02-19

At Michaels (OH2AUE) lab, clock 14-22

Again high adjustment activity:

Present were OH2LKV, OH3UW, OH2JCP, OH1JJC, OH2MQK, OH2LFM, OH2LH, and OH2AUE.

Catering, and other supplies were arranged at this time by OH1JJC, OH2JCP, and OH2LFM.

English translation is partial..

• Weller tips were cleaned in soda, but to no avail, new ones must be bought.
• Reading Vector Network Analyzer 3.5" diskettes was not successfull during the session.   Next day OH2MQK solved it: The VNA has a "DD" drive, and the diskettes were of "HD" type ==> PC didn't understand resulting diskettes. A bit of tape solved the issue: [diskette]
• Bi-component poly-urethane foaming was done to translator 144 MHz receiver turnstile antenna, and also for ATV-Tx's 1.3 GHz Big Wheel. (2m:   1, 2, 3, 4, 5;   1.3 GHz:   1.)
• OH2LKV did tune of translator 70 cm turnstile antenna, and in presently limited "free space", the result was return loss of over 20 dB.

  70cm turnstile antenna return loss plot:
  
  "Taajuus" = Frequency, "Heijastusvaimennus" = return loss

• OH2AUE did construct temporary GPS repeater into the underground lab.   This allowed testing ATV-OSD device with actual position and time data on screen.   An unpleasantness has been observed at the ATV-Tx: Its PLL locks rarely at wanted frequency. This needs further investigation, as the intention is to power-cycle the Tx by IHU. Suspect is poor reseting of PIC due to too slowly raising power.
  (GPS rptr:   sch;   photo:  1, 2b, 3b; (2, 3)
  (ATV Tx:   1)
  
• The ATV-TX overlay text contast needs considerable increase. Camera video sync pulse, and colour subcarrier burst are of roughly correct amplitude, but camera AGC and camera white level limitter are unnecessarily high. Nothing can be done to those. (photo: atv osd picture)
• GPS/OSD-interface linear power regulator has been changed into a switcher, and observed functional. Power consumption was roughly halved (2W -> 1W)
• Jari, OH3UW, modified and tuned APRS-TX to its correct frequency ("I don't like at all of these negative power beasts") with higher phase comparison frequency to improve spectral purity.   Considerable remainder-FM is still observable in the unit.   When heading for home, he took the unit with him, and also power switcher prototype to produce -12V from system bus +14V.
  (photos:   tuning1, tuning2, spectrum, sch, sch2)

Builders elsewere:

• Janne, OH1LRY, has enclosed the translator, and its enclosure is drilled full of adjustment holes.   Closing the enclosure didn't affect adversally on the functioning of the translator.
• Vesa, OH2JCP, has completed the command receiver, except that its linear regulator shall be removed (9 V will be available from translator power supplies), and chrystal filter 50-ohm input needs matching to IF-hybride's 1.5k-ohm impedance. (Photos:   1, 2, 3)
• Hessu, OH2LH, is constructing 80m beacon into "Ilmari-standard" enclosure.

2003-02-21 OH2AUE did some additional work:

ATV transmitter antenna

Today I spent time tuning Ilmari ATV transmitter flight antenna back to proper resonance. (Poly-urethane foam's Er loaded antenna resonance frequency down circa 35 MHz, thus elements had to be shortened by about 10 mm!) New, final matching is like this:

Matching is measured with a non-critical conductive ground-plane simulating Ilmari internal chasses.

Real matching for the PA transmitter output

ATV LPF

APRS-TX spectrum images

More scarier picture of transmitter's remainder-FM (yes, 2 kHz/div!):a

OH3UW will study the loop filter, if that can be speeded up.

Command receiver

The command receiver is recycled from somewhere by OH2JCP. It encountered a bit of modifications, and is now nearly complete.   The integrated linear regulator was removed, as it can get its 9 V feed from translator power supply.   power consumption at 8.5 V is 6 mA.

Chrystal filter's 50-ohm input is matched to 1 k-ohm signal with a small ferrite transformer. Primary: 2 turns, secondary: 40 turns. Input sensitivity (direct to xtal filter 50-ohm input) is -96 dBm @ 50 ohm (10 dB SINAD). Audio output is scalable with original trimmer in range of 50 .. 200 mW to highish-impedance load (~ tens of k-ohms).

2003-02-27 OH2AUE did some more additional work:

Finnish only, at first..

Ilmarin ATV-TX:n PLL:n lukkiutumisongelmaa tuli tutkittua. Kortilla oleva PIC ei aina anna ulos sarjadataa + kelloa, erityisesti, kun sähkö on siivotonta (lue: klipsi johdon päässä). Jos malttaa odottaa pari sekuntia ja tehdä tämän jälkeen jämäkkä sähkön kytkentä powerille, lukkiutuu VCO _aina_ nätisti: PIC lähettää PLL-piirille jakoluvun. Kyseessä siis lienee puhtaasti mikrokontrollerin huono resetoituminen...

Asia täytynee korjata seuraavassa säätösessiossa, kun meillä on leegio bittisäätäjiä mukana kuviossa :-)

Sama tilanne oikeastaan koski myös GPS-interfacea, jonka ATMEL:in mikrokontrolleri toisinaan meni ilmeisesti jonkinasteiseen latchuppiin, sillä se saattoi vetää puolikin ampeeria ja lämmetä vastaavasti _hieman_ speksattua enemmän :-( Tähän tuntui auttavan RC-/diodi-resetpiirin lisäys. Tämän jälkeen en saanut piiriä enää menemään moiseen vaaralliseen tilaan.

Kameroista: ikävä kyllä näiden AGC ja valkoisen tason leikkain on säädetty päin prinkkalaa. Jos deviaation säätää siten, että "referenssivastaanottimella" saadaan 75 ohmiin 300 mV:n tahdistuspulssi, on aktiivivideota lähes koko voltti päälle, kun pitäisi olla 700 mV. Jos videon säätää niin, että kuvan kirkkausdynamiikka on oikeaoppinen 700 mV, niin synkkapulssit jäävät aika lyhyeksi. Tuokaan ei muuten vielä haittaisi, mutta voihan nenä, että kameran videoklamppi pettä pahemman kerran kentänvaihtopulssin ja tasauspulssien kohdalla !!! Vesan kanssa tämän jo kertaalleen katsoimme, mutta ongelmaa ei näkynyt, koska videoskoopin oma klamppi oli päällä - oma vikani.

Näiden kanssa täytyy ilmeisesti elää. Kunnon ulko- testi paljastanee käytettävyyden (auringonpaiste jne.).

Jäi tuo purkkien "pellitys" vielä tekemättä, kun ainakin tuota ohjaimen PIC:iä joutuu säätämään vielä.

Text: OH2AUE.
Editing/english: OH2MQK.