[AMRadio] Ferroresonant transformer revisited

W5OMR/Geoff w5omr at satx.rr.com
Wed May 10 16:00:00 EDT 2006

Jim Candela wrote:

>Yea right! You would still run < 100 watts RF output
>to keep the neighbors happy! Hmmm, power input 150
>watts + plus 315 watts filament for 100 watts output.
>Isn't that about 22% efficient? :-)

I'm running 4 250TH's in the rig now, at 1500v on the plates @ 100mA in 
the final.  That's 150w DC input, for 100w of carrier output.

I'm driving the final with a Viking II with an output of 50w, to get 
125mA of grid drive, for a PAIR of 250TH's.

the modulator (a pair of 250TH's, as mentioned above) rests at 200mA at 
1500v.  That's 300w.  Class A?  At least AB1.

don't forget the speech-amp - a 50w Bogen PA, running 4 8417's in p-p 

all that, yes, to do my part to keep the nieghbors happy. 

Between 1 and 6am though, look out!

I shove the link in, for 300mA, the B+ goes up on the modulator to 
2800v, the modulator bias is re-adjusted for 120mA (now in Class B), and 
the knobs on the Speech-amp go another 'click' to the right (mic -and- 
Master gain go from '3' to '4') and the final now produces 350w of 
carrier output, with asymmetrical audio peaks of 5 and 6:1.

No problem!

73 = Best Regards,

More information about the AMRadio mailing list

This page last updated 16 Jan 2018.