[Milsurplus] RE-2 meter

[Mike Feher]

No, he was measuring the meter independent of the thermocouple. The 0.75A goes through a shunt that has the thermocouple across it. That much current would burn out the thermocouple. 73 - Mike 

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
908-902-3831

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> On Behalf Of hwhall--- via Milsurplus
Sent: Tuesday, June 17, 2025 11:18 PM
To: elden meyer <elden_meyer at yahoo.com>; Mark K3MSB <mark.k3msb at gmail.com>
Cc: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] RE-2 meter

In Elden's data, isn't that 0.75A thru the thermocouple heater & not thru the meter, though? The RF current never goes thru the meter movement, only thru the heater part of the thermocouple. 

I think we'd all been trying to figure out how the meter movement had such a low resistance but perhaps it was only the heater instead.

Wayne
WB4OGM

On Tuesday, June 17, 2025 at 07:11:35 PM MDT, Mark K3MSB <mark.k3msb at gmail.com> wrote: 

Thanks Elden.

19.5 mV with a 3 ohm internal resistance yields 6.3 mA FS, which is close to my 5 mA measured on two different meters.  Being 85 years old, I find the difference understandable.

The markings on the Thermocouple do indeed indicate a max of 0.75 A:

I have a problem with the chart.   With a 3 ohm internal resistance,  here's the voltage across the meter with the indicated current values:

With a meter reading of 1,  the voltage across the meter is 18X the FS value of 19.5 mV.

If 19.5 mV is FS, and that's with 0.75 A through the meter,  then the internal resistance is 0.026 ohms, which is in the ballpark of my value of  0.033 ohms. 

73 Mark K3MSB





On Tue, Jun 17, 2025 at 5:53 PM elden meyer via Milsurplus <milsurplus at mailman.qth.net> wrote:
> Good Afternoon,
> 
> In the June 1963 Surplus issue of 73 magazine Roy Pafenberg writes about the antenna relay. 
> 
> He gives this data: 
> 
> meter only - 3 ohms DC resistance, 19.5 millivolts full scale
> 
> with thermocouple -
> reading , RF amps
> 1  , 0.12
> 2  ,  0.18
> 3  , 0.22
> 4  , 0.26
> 5  , 0.32
> 6  , 0.37
> 7  , 0.43
> 8  , 0.50
> 9  , 0.59
> 10 , 0.75
> 
> Elden
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net Please help support this email 
> list: http://www.qsl.net/donate.html

______________________________________________________________
Milsurplus mailing list
Home: http://mailman.qth.net/mailman/listinfo/milsurplus
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Milsurplus at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________
Milsurplus mailing list
Home: http://mailman.qth.net/mailman/listinfo/milsurplus
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Milsurplus at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html


-- 
This email has been checked for viruses by Avast antivirus software.
www.avast.com