Idioot se gids tot kragbronne
If you’re planning to power your transmitter from batteries than skip this section! You might want to read it to get an idea of what it takes to power transmitter off the mains voltage.
Die meeste kleiner tuisgeboude of lae kragsenders benodig 'n goeie 12-15 volt, 2A (minimum) tot 10A (sterker 50W of 100W senders) stabilized mains power supply. Note stabilized was printed in bold type, meaning output voltage is regulated and stabilized to specific voltage with minimum noise or fluctuation. The noise can usually be heard as a hum (50/60Hz). If switching power supply is used noise can appear at the switching frequency and produce weird results when mixing with other signals in the transmitter.
Wall-wart types are sometimes not of stabilized type. Worst can output even 20V when in load-free mode and only go down to rated 12V under load. This is not what you want to use as it may damage your transmitter and will definitely present as a strong 50/60Hz hum on your signal from the lack of proper stabilization. Short circuit protection is useful but not mandatory. A fuse serves well instead of protection and you should definitely use one. They cost 5 cents and a final RF transistor can cost you more than 100 US$/Euro.
Verstelbare uitsetspanning gee jou 'n bykomende kenmerk, jy sal jou sender se uitsetkrag kan verander deur die spanning van jou kragtoevoer te verander. Nie sleg nie. Jy kan soms meer krag uit jou sender druk as jy net 'n bietjie die spanning oor die nominale spanning vir jou sender verhoog. Maar wees versigtig, dit sal waarskynlik jou uitsettransistor vernietig, sommige elektrolitiese kapasitors laat opblaas of oormatige verhitting veroorsaak. MAXPRO-opwekkers kan tot ongeveer 15.5V maksimum neem voordat skade plaasvind.
Importance of proper power supply is often underestimated. Poor power supply can cause several serious problems; add hum to your signal, cause interference to your neighbors (typical for AM systems where RF leaks into power lines), low current rating, unstable operation under RF field etc. Complicated laboratory power supply units with lots of poorly shielded electronics are often susceptible to RF fields meaning they can uncontrollably raise their output voltage or short-circuit protection can trip when the current is not even reaching 10% of the limit. A good power supply for transmitters should be RF shielded.
Aanvaarbare eenhede is deesdae teen winskooppryse beskikbaar, aanlynwinkels soos Mouser of Digikey het dit, asook hamradiowinkels en hamfeeste. Ons verkoop 'n aantal modelle self hier. Laespanning 15V weergawes is beskikbaar hier. Sterker senders werk dikwels vanaf 48V of selfs 65V. Ons sterkste hoofkragbron kan tot ongeveer 2000W FM-sender aandryf. As jy verkies om jou toerusting self te bou, kry jou soldeerboute en kyk na hierdie projekte hieronder. Volg altyd veiligheidsreëls wanneer hoofspanning hanteer word, foute kan dodelik wees!
Verstelbare 1A kragtoevoer
This is a simple variable output power supply. Now, left of this circuit would be standard line voltage transformer (110-220/18V) and a standard rectifier block with smoothing caps (10000uF or more). The heatsink of the 317 regulator must be isolated from the ground (aluminum heatsink).
3A 13.8V vaste-spanning kragtoevoer;
Dit is 'n redelik reguit vorentoe-baan. Jy sal dalk C5 met 'n groter kapasitor (10-100uF) moet omseil. Diode D maak op vir die BE-verlies van 0.7V van die 2N3055-transistor. As jy hoër spanning benodig, gebruik 7815 in plaas van 7812 en koppel pen 3 direk aan grond. Dit sal jou 14-14.3V op die uitset gee. Ek het verskeie kragbronne soos die gebou vir my CB/ham stasies en hulle werk baie goed. Natuurlik moet jy net soos hierbo hooftransformator en gelykrigterbrug + gladdoppies byvoeg. Doppies moet so groot as moontlik wees (20000uF of meer).
28V hoëstroom kragtoevoer vir 40-200W RF kragversterkers;
Hierdie ontwerp is uit die ARRL-handboek 2005, ons beveel hierdie boek aan vir enigiemand aangesien dit alle aspekte in RF-ontwerp dek, insluitend antennas, senders, basiese electronics, filters, versterkers en ander. Hierdie kragtoevoer is baie gerieflik vir 40-200W RF-versterkers wat dikwels vanaf 24V werk. Gaan ARRL-handboek na vir PCB-uitleg en bykomende besonderhede. Ons het selfs 'n skakel na hierdie boek in ons Aanbevole leeswerk afdeling.
Bespreek hierdie artikel in ons Forum!
