Courier ML100 Mobile Linear Amplifier(Tube)?

Hello,
I just signed up and registered to this forum and noticed your question about the so called "squeal" in your Courier ML100 mobil linear amp. I see your question was posted way back in '04, so this answer I'm sure, has already been answered by now seeing as it is a "dollar short and 4 years late" ! If by chance you still have that linear and have not to date received an answer to your question (I see no reply to your question posted--to date) here it is: the "squeal" you refer to is a "normal function" of this linear and you will hear a similar one in just about any hi power "TUBE" equipment running in a mobil environment wheather it be a linear amplifier or a complete transmitter / transceiver unit. The "squeal" you refer to is caused by the 12 volt to 700 volt DC-DC converter power supply. This converter supply operates at approx. 3000HZ (thus the "squeal") as it "chops" the 12 volts DC from your car's battery system and steps it up to a fairly powerful (and leathal) 700 volts DC for the plate (anode) supply for the 12JB6 final (grounded grid) amplifier tubes, via a step up converter transformer. The tubes filaments (heaters) which you see glowing operate "directly" off the 12 volt car battery supply, thus the "12" in the 12JB6 tube number, however the rest of the elements of the tubes require substantially more than this meager 12 volts in order to operate--typically in the order of 500-1000 volts in transmitter applications. The 'squeal' you hear is only when "keying" the linear due to the fact that this 700 volts of B+ is only required and applied to the final output tubes when the linear is actively producing power (transmitting) I am "very" familiar with this and many other linears (I own one of these Couriers) and they all work on pretty much the same basic principal. The only mobil linears which "do not" have this DC-DC converter supply and it's "inherint squeal" (or "buzz" in case of a vibrator supply) are the totally "solid state" (non-tube) type linears which operate entirely from one end to the other directly off the 12 volt battery system. These 'solid state' amplifiers do not require the high voltages as do the vacuum tubes elements and therefore do not have the DC chopper supplies and their tell-tale "squeals". There are/were "some" special vacuum tubes that operated totally from only 12 volts DC but none of them produced any real power and were used mostly for low level "signal' amplification applications in radio receivers and NOT power amplifiers of any substantial power levels. Hope this info helped you out. The squeal you hear in your linear is a quite NORMAL function of it's proper operation, if it don't squeal -it don't work!--don't mess with it!! Take care and watch out for "high" voltage!

Mosfet,
I read your reply,and I must say,,very nicely put,in theory..But,,all ya realy had too say,was that it is the geranium transitors that are causing the whine..lol And that is the way they work..

Not too say anything bad too ya now,,don't get me wrong..But I dout he even understood half of what ya said..lol

I know I'm showing my age,,but I used too run a few of those in my ol mobile back in the day..Maco's ..I loved my o'l tube type mobiles..lol

Great reply though,,for those of us that understood it..


rfp

rfpowerman said:

Mosfet,
I read your reply,and I must say,,very nicely put,in theory..But,,all ya realy had too say,was that it is the geranium transitors that are causing the whine..lol And that is the way they work..

Not too say anything bad too ya now,,don't get me wrong..But I dout he even understood half of what ya said..lol

I know I'm showing my age,,but I used too run a few of those in my ol mobile back in the day..Maco's ..I loved my o'l tube type mobiles..lol

Great reply though,,for those of us that understood it..


rfp

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I know this is a rather old post, and I don't even know if you're still alive. However, I feel the need to respond. I thought the other guy's reply was very thorough and concise, and made it easy to fully understand what's happening... as opposed to your lazy and inaccurate explanation. By the way, it's 'germanium' and 'to'. To as to go away, too as to too many spelling errors. And doubt has a b in it. B as in bee in my bonnet.