Hi! we all learned a few things during the CB days and the 2Meter days. Yes RF shock is real. May humawag dun sa car antenna ng VHF TX putting out 45 watts. wham...RF is real energy. Gamit noon neon bulb to sense RF. Ewan ko lang kung sisindi yung nasa screwdriver pang testing AC. Alisin ciguru yung resistor sa loob. I kept schematics but I do not know where they are. I have a book on CB, yung luma na 21 channels pa at maraming crystals. I also have the Motorola handbooks.
On the buring of the finals when we transmit without an antenna, we noted that the UFH Icom on 430 Megs was in fact more prone to burning. That is probably one reason the FRS radios on 430Megs have fixed antennas.
I built several transmitters for RC (max 1 watt) and noted that the final Q is highly reversed biased with a 470 ohm resistor. Other than setting the region in which he final Q should operate,from a practical perspective, protection yung dun sa Q para hindi mag "runaway".
The final Q is driven by a driver Q either via a capacitor or via a transformer. The final Q is made to oscillate at the driven frequency but at a higher amplitude (higher current). The high f energy is made to run through the coax to an antenna. We can imagine the signal as nag cha cha cha dun sa antenna. Urong sulong. Kung ang run niya perfect fun sa length ng element, yun mag vivibrate yung antenna sa optimum level and will radiate the energy into free space. kapag hindi tuned and antenna, some energy will return to the final Q. Ito nga ang VSWR, comparing the forward signal to the reversed signal. Usually up to 1.5 and acceptable. Now pag WALANG ANTENNA..... hmmmmm. The energy run through the coax and does not find a "load" sa dulo. Remember sa audio amp, we face the same risk. Pag walang speaker sa dulo, walang load, baka masunog and amp section. mas lalo na kapag walang coax pati. Oopssss. Hinde na reflected power kasi di nga nakalabas. Kulob power na. Yung final transistor keeps oscillating at high F and high current na walang labasan. Mag runaway siya, thermal runaway. Ayun, pssttt.....Ala ng signal.
Ang SWR ay importante and we can make one. Sa ARRL. Pwede magburn and finals kahit may antenna na masyado mataas and SWR (Standing Wave Ratio). Yung pang 250 kwatts. Aruy, ang lakas ang energy nakakulob.