Antenna too long

Lets get real, we are talking about a piddling little battery operated transmitter that would take a three years and four months to heat a cup of coffee!
If the output transister used cost more than a packet of matches to make, then it should handle an open circuit load.
If you un-hooked it from the 8 valve output stage, 10 kilowatt, radio transmitter that I used to repair back around the end of the 70's, then you could expect to see a few sparks.......
Hope this helps, Peter
Reply to
Bushy
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From Peter:
What is involved is not an 'open circuit load' but a severely _mismatched_ load, resulting in the output device having to eat a lot of reflected power that'd otherwise be going out the antenna. The result is a rise in current thru the output transistor. (remember how you used to have to 'dip' the current for resonance when tuning the finals in a broadcast xmitter?) In CB xmitters you can zorch the final in a heartbeat with a mismatched feedline. Thankfully, our little RC xmitters apparently have the sufficient overcurrent protection on the final to avoid disaster with the antenna down. I still wince every time I see it done, though. Bill (oc)
Reply to
Bill Sheppard
An open or shorted antenna output is THE WORST SWR than can be achieved....... 100% reflected power.
CB xmtrs have been idiot proofed since the late 1970's..... for preciously the reason someone else stated - people were bring back units with blown finals. You can leave the antenna disconnected or put a shorted UHF connector on the antenna jack and put a brick on the mike switch. As long as the 12v keeps coming, the final transistor will stay hot dissipating the heat generated!
RC xmtrs are the same!
David
Reply to
David AMA40795 / KC5UH
From David=A0AMA40795=A0/=A0KC5UH):
Yeah, the last I worked on CBs was in the 70s when people were blowing their finals faster than we could replace them. Apparently CBs have been idiot-proofed since then.
I still wince out of habit though, every time I see someone run their RC xmittr with the antenna down. Even though knowing it's "safe", i never do it, just from the experience with the old CBs.
Bill (oc)
Reply to
Bill Sheppard
You'd run and hide when I do RC range checks...... I remove the antenna completely. Range should be about 40 ft....... saves my arthritis plagued body lots of walking.
David
Reply to
David AMA40795 / KC5UH
I am having enough trouble trying to log in here already. Not really complaining, though I had to enter my ID and password twice. Anyone know an easier way?
But Jim, Red was proposing an automatic switch when the antenna is to be raised. However, I agree with you about too many gizmos to complicate our hobby.
You are the one who is being creative. "Col. Sherman", "shell shocked" and all.
Wan
Reply to
Wan

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