Re: [AMRadio] Safe Metering for Blind Operators
Hello, The Johnson Viking II also uses negative return shunts for both the final and the modulator current takeoff point. A word of warning tho. If the ground or B minus side of the shunt lifts in this type of connection the meter will most likely be pulled up to the B+ voltage relative to chassis. My VK II with it's small loops of Ni Chrome for shunts did exactly that when whatever treatment that was given the unsolderable NiChrome let loose. I have often seen panel meters offered on E-Bay and at HamFests that had at least one adjustable setpoint pointer that activated a contact closure when reached.The difficulty would be in finding the right meter resistance for the application. Bill Courtright KB3DKS/1
Re: [AMRadio] Safe Metering for Blind Operators
Hi Mike; I have a Heathkit DX-100B. The plate meter is across a .1 ohm resistor from the center tap of the HV transformer to ground. This should serve your needs. Good luck. 73, Ed Richards K6UUZ On Mon, 3 Jan 2005 12:43:25 -0600 "Mike Duke, K5XU" <[EMAIL PROTECTED]> writes: > K4KYV wrote: > > "In my homebrew rigs with triode finals, I place the plate meters > between > the > common point for grid leak/bias supply and PA filament, and ground. > The > Gates BC1-T does it the same way, with no HV on the meter." > > > I've been reading the discussion of safe metering with great > interest, as > perhaps explained by my subject line and signature. > > I would love to find a good plate modulated transmitter in the power > class > of a DX100 or Valiant, in which the plate meter would not have the > full > plate voltage across its terminals. Is anyone aware of a commercial > or > surplus transmitter with this design feature? > > I could easily and safely tune such a transmitter by connecting an > audible > meter-reading device across the meter terminals. I still have the > circuit > which I used successfully with a DX60, and very cautiously with a > Viking > Ranger from 1969 - 1974. I learned quickly that the ranger meter is > at full > plate potential. The good news is that I lived to tell about the > experience. > > I also recall reading somewhere of using a voltage divider in order > to > obtain a safe potential level in the external audible reader. If > anyone on > this list has ever encountered a transmitter which was modified in > this way, > I'd like to know more about how it was done, since I'd love to put a > Ranger > on the air in order to re-create my first station. > > The point can be made that the easiest route is to put a rice box > and linear > combination on the air. Yes, that would be the easiest thing for > anyone, > but, not nearly as much fun! > > > Mike Duke, K5XU > American Council of Blind Radio Amateurs > > > > > > -- > No virus found in this outgoing message. > Checked by AVG Anti-Virus. > Version: 7.0.298 / Virus Database: 265.6.7 - Release Date: > 12/30/2004 > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net >
[AMRadio] Safe Metering for Blind Operators
K4KYV wrote: "In my homebrew rigs with triode finals, I place the plate meters between the common point for grid leak/bias supply and PA filament, and ground. The Gates BC1-T does it the same way, with no HV on the meter." I've been reading the discussion of safe metering with great interest, as perhaps explained by my subject line and signature. I would love to find a good plate modulated transmitter in the power class of a DX100 or Valiant, in which the plate meter would not have the full plate voltage across its terminals. Is anyone aware of a commercial or surplus transmitter with this design feature? I could easily and safely tune such a transmitter by connecting an audible meter-reading device across the meter terminals. I still have the circuit which I used successfully with a DX60, and very cautiously with a Viking Ranger from 1969 - 1974. I learned quickly that the ranger meter is at full plate potential. The good news is that I lived to tell about the experience. I also recall reading somewhere of using a voltage divider in order to obtain a safe potential level in the external audible reader. If anyone on this list has ever encountered a transmitter which was modified in this way, I'd like to know more about how it was done, since I'd love to put a Ranger on the air in order to re-create my first station. The point can be made that the easiest route is to put a rice box and linear combination on the air. Yes, that would be the easiest thing for anyone, but, not nearly as much fun! Mike Duke, K5XU American Council of Blind Radio Amateurs -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.298 / Virus Database: 265.6.7 - Release Date: 12/30/2004
