[ARC5] HAs anyone tried the RF thermocouple on VHF?

[Scott Johnson]

Yes, but those thermocouples are nearly microscopic, and are measuring the temperature rise of a carbon film load.  There are actually two or more thermocouples, one for ambient temperature compensation, and another to measure the load temperature.  The HP 84XX series are a good example.  Thermistors based sensors are (were) used widely, and are considered reference standards.  More recently , diode type meters have become predominant, due to their high speed and ability to measure pulsed power accurately.  I use all three types, as well as directional line samplers (Bird), and even calorimetric (HP-434A) which has PLUMBING! (A pump, copper tubing, oil, tubes, high voltage, a fan; pretty much everything electrical and mechanical)  Best way to accurately measure mid-power microwave power in the late fifties! (see: http://www.radiomuseum.org/r/hewlett_pa_calorimetric_power_meter.html )

Regards,

Scott V. Johnson W7SVJ
5111 E. Sharon Dr.
Scottsdale, AZ 85254-3636
H (602) 953-5779
C (480) 550-2358
scottjohnson1 at cox.net
scott.johnson at ieee.org

-----Original Message-----
From: Peter Gottlieb [mailto:kb2vtl at gmail.com] 
Sent: Thursday, September 7, 2017 6:21 AM
To: Scott Johnson <scottjohnson1 at cox.net>
Cc: Bill Cromwell <wrcromwell at gmail.com>; arc5 at mailman.qth.net
Subject: Re: [ARC5] HAs anyone tried the RF thermocouple on VHF?

But thermocouples are used in precision power measurement equipment well through microwaves. 


Peter

> On Sep 7, 2017, at 9:09 AM, Scott Johnson <scottjohnson1 at cox.net> wrote:
> 
> As a rule, RF thermocouples become too reactive at even the upper HF frequencies to be of any practical use.
> 
> Scott V. Johnson W7SVJ
> 5111 E. Sharon Dr.
> Scottsdale, AZ 85254-3636
> H (602) 953-5779
> C (480) 550-2358
> scottjohnson1 at cox.net
> scott.johnson at ieee.org
> 
> -----Original Message-----
> From: arc5-bounces at mailman.qth.net 
> [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Bill Cromwell
> Sent: Thursday, September 7, 2017 6:06 AM
> To: arc5 at mailman.qth.net
> Subject: Re: [ARC5] HAs anyone tried the RF thermocouple on VHF?
> 
> Heh,
> 
> I still use a light bulb dummy load every once ina  while. But I have to listen on frequency with a real antenna first. Light bulbs radiate. I discovered that when I put on on a transceiver and started copying 40 meter stations! Out of curiosity I tried some QSOs with the light bulb and I got a few. Don't try that with your newfangled silicon final transmitter - even though I have done that too (and got away with it).
> 
> Of course, that us not VHF, either.
> 
> 73,
> 
> Bill  KU8H
> 
>> On 09/07/2017 08:53 AM, David Stinson wrote:
>> 
>> 
>> 
>> 
>> *From:*J Mcvey via ARC5, 2017 9:00 PM
>> *Subject:* [ARC5] HAs anyone tried the RF thermocouple on VHF?
>> 
>> 
>> 
>> Did they have an ammeter for the T-23?
>> 
>> ------------------------
>> 
>> 
>> 
>> The T-23 does not use an RF Current sensing thermocouple.
>> 
>> “By the book” tune-up uses a remote-meter test set and a
>> 
>> 50-ohm dummy load with light bulbs to indicate current.
>> 
>> 
>> 
>> 73 Dave AB5S
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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> 
> --
> bark less - wag more
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