Re: [AMRadio] Globar brand thermistors
Don't confuse Globar thermistors with Globar resistors. The latter are non-inductive power resistors often used in dummy loads and parasitic suppressors. My dummy load is made up of a dozen 600 ohm 150 watt Globars. Each one is about 18 long and 1 in diameter. Supposedly you can heat them to a dull red glow without hurting them, but I have never tried running that much power, and I'm not sure what such abuse would do to the resistance. I have heard of the ones used in parasitic suppressors of high power BC transmitters (50 kw) glowing under parasitic conditions. Don
Re: [AMRadio] Globar brand thermistors
Now that you mention it Don, I remember those Globar resistors your talking about. The card that the thermistor I used in the 117Z6 circuit listed it as a resistor. It was made by Workman Electronics and clearly stated that it was a Globar Resistor. I had it left over from my TV days. I installed it and tested it. It was about 150 ohms cold. And dropped to around 6 ohms after a very short warm up. So it most certainly is better described as a thermistor. I have no clue as to why Workman would package it saying Golbar Resistor, but that's what they did. George KE4HJ Donald Chester wrote: Don't confuse Globar thermistors with Globar resistors. The latter are non-inductive power resistors often used in dummy loads and parasitic suppressors. My dummy load is made up of a dozen 600 ohm 150 watt Globars. Each one is about 18 long and 1 in diameter. Supposedly you can heat them to a dull red glow without hurting them, but I have never tried running that much power, and I'm not sure what such abuse would do to the resistance. I have heard of the ones used in parasitic suppressors of high power BC transmitters (50 kw) glowing under parasitic conditions. Don __ 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] Globar Brand Thermistors
George KE4HJ and Others- I worked for Electronic Parts Company in Albuquerque, New Mexico from 1977 through 1993. We stocked the full line of Workman Electronic Products of Glowbar brand thermistors. The values 85 to 100 ohms seems to be correct. As you and others indicated they were used to minimize voltage surge when an electronic product was initially turned on. A good idea for any electronic product that uses tubes, especially rectifiers and regulators as they are in the front end of the circuit. And yes the ones for the AC line were Negative Temperature Coeffiecient, while the degaussing circuit on a color TV was Positive Temperature Coefficient. Bob WB5YYX Life Member New Mexico Radio Collectors Club Antique Wireless Association MemberNo virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.322 / Virus Database: 266.11.17 - Release Date: 5/25/2005
Re: [AMRadio] Globar brand thermistors
That makes sense, because it would cut off the degausser better. The hot unit would work as an inrush limiter, then. Its resistance drops as it gets hot, so it is an NTC thermistor. Bacon, WA3WDR - Original Message - From: John Coleman [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Thursday, May 26, 2005 6:34 PM Subject: RE: [AMRadio] Globar brand thermistors As I recall the hot one was in series with the supply to the TV circuitry and the other was in series with the degaussing coil, the degaussing coil and its series cold resistor device was placed in shunt with the hot resistor. In this way the voltage drop across the hot resistor went very low and the cold resistor (as it was called) would not conduct unless the voltage was above a certain value. Therefore in a few seconds the current through the degaussing coil would drop to nothing. John, WA5BXO
Re: [AMRadio] Globar Brand Thermistors
I think George mentioned he only found one. If that is the case you should put a polarized line cord on the unit and put the Globar in series with the hot lead, provided the Globar is a NTC. 73 Jim W5JO George KE4HJ and Others- I worked for Electronic Parts Company in Albuquerque, New Mexico from 1977 through 1993. We stocked the full line of Workman Electronic Products of Glowbar brand thermistors. The values 85 to 100 ohms seems to be correct. As you and others indicated they were used to minimize voltage surge when an electronic product was initially turned on. A good idea for any electronic product that uses tubes, especially rectifiers and regulators as they are in the front end of the circuit. And yes the ones for the AC line were Negative Temperature Coeffiecient, while the degaussing circuit on a color TV was Positive Temperature Coefficient. Bob WB5YYX Life Member New Mexico Radio Collectors Club Antique Wireless Association Member
[AMRadio] Globar brand thermistors
Those things are really pretty cool. I think they are around 100 ohms cold and about 1 ohm hot at up to 3 amps. They are great for the primary of filament XFMRs for Xmitting tubes. I used to use them all the time. We kept them in stock for the degaussing circuits in TV repair but I haven't seen them for a long time. John Coleman, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Wilhite Sent: Thursday, May 26, 2005 1:41 PM To: Discussion of AM Radio Subject: Re: [AMRadio] 117Z6GT question George: You might search around for some old Globar resistors. Install on the input line and they will absorb some of that inrush resulting in longer life for the tubes. I found a card of them (they were in little packets that one pulled off like the pull tabs you bought at the beer joint) in little bags. They were used in TV sets and AC/DC radios. Check for a parts store that has been in business for a long time and find the guy with gray hair and an unsteady walk. He will know what you are talking about. 73 Jim W5JO
Re: [AMRadio] Globar brand thermistors
Cold resistances varied some. Hallicrafters used them in TV sets as well as AC/DC sets, as did other manufacturers Cold resistance varied from just over 100 ohms to about 85, if memory serves correct. I found several at a parts store where I lived before and a friend of mine wanted several. I don't think he wanted as many as I sent, but he is supplied for life. Those of you who have old stores in their areas might check. Perfect for what John mentioned and for the AC sets with no transformer such as the Scott SLRM. 73 Jim W5JO - Original Message - From: John Coleman [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Thursday, May 26, 2005 3:20 PM Subject: [AMRadio] Globar brand thermistors Those things are really pretty cool. I think they are around 100 ohms cold and about 1 ohm hot at up to 3 amps. They are great for the primary of filament XFMRs for Xmitting tubes. I used to use them all the time. We kept them in stock for the degaussing circuits in TV repair but I haven't seen them for a long time. John Coleman, WA5BXO
Re: [AMRadio] Globar brand thermistors
One thing about those Globar units - the type you want for the filament string is not the same as the type you want for the degausser. You want an NTC (negative temperature coefficient) type for filament string inrush current control, and you want a PTC (Positive Temperature Coefficient) type for the degausser. Digi-Key ( www.digikey.com ) has these units under NTC Thermistors and PTC Thermistors. I don't know if Globar is still around, but a lot of companies make them. Bacon, WA3WDR - Original Message - From: gwt [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Discussion of AM Radio amradio@mailman.qth.net Sent: Thursday, May 26, 2005 5:09 PM Subject: Re: [AMRadio] Globar brand thermistors Yea, when Jim reminded me of those globars, I realized that would be perfect to slow down the current surge on my my old radio with the 117Z6 rectifier, that lights up like a light bulb when you first turn it on! That's gotta shorten the life of the tube, big time! In my mind's eye, I could see one of those globars, still in the card, someplace in all my old TV krap that I never threw away. The question is - can I find it? So I headed out to my storage area, rumaged around, found my old tube caddy, and found the globar, still in it's wrapping, just like I saw it in my mind's eye. Way Kool! 73, George KE4HJ
RE: [AMRadio] Globar brand thermistors
Yes, the Scott slrm I have has a few of them in the AC line I think, and that receiver starts up nice. God help me if I had to replace one of them... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of gwt Sent: Thursday, May 26, 2005 5:09 PM To: [EMAIL PROTECTED]; Discussion of AM Radio Subject: Re: [AMRadio] Globar brand thermistors Yea, when Jim reminded me of those globars, I realized that would be perfect to slow down the current surge on my old radio with the 117Z6 rectifier, that lights up like a light bulb when you first turn it on! That's gotta shorten the life of the tube, big time! In my mind's eye, I could see one of those globars, still in the card, someplace in all my old TV krap that I never threw away. The question is - can I find it? So I headed out to my storage area, rumaged around, found my old tube caddy, and found the globar, still in it's wrapping, just like I saw it in my mind's eye. Way Kool! 73, George KE4HJ John Coleman wrote: Those things are really pretty cool. I think they are around 100 ohms cold and about 1 ohm hot at up to 3 amps. They are great for the primary of filament XFMRs for Xmitting tubes. I used to use them all the time. We kept them in stock for the degaussing circuits in TV repair but I haven't seen them for a long time. John Coleman, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Wilhite Sent: Thursday, May 26, 2005 1:41 PM To: Discussion of AM Radio Subject: Re: [AMRadio] 117Z6GT question George: You might search around for some old Globar resistors. Install on the input line and they will absorb some of that inrush resulting in longer life for the tubes. I found a card of them (they were in little packets that one pulled off like the pull tabs you bought at the beer joint) in little bags. They were used in TV sets and AC/DC radios. Check for a parts store that has been in business for a long time and find the guy with gray hair and an unsteady walk. He will know what you are talking about. 73 Jim W5JO __ 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 mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Globar brand thermistors
Thanks for the info, Bob. George KE4HJ Bob Bruhns wrote: One thing about those Globar units - the type you want for the filament string is not the same as the type you want for the degausser. You want an NTC (negative temperature coefficient) type for filament string inrush current control, and you want a PTC (Positive Temperature Coefficient) type for the degausser. Digi-Key ( www.digikey.com ) has these units under NTC Thermistors and PTC Thermistors. I don't know if Globar is still around, but a lot of companies make them. Bacon, WA3WDR - Original Message - From: gwt [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Discussion of AM Radio amradio@mailman.qth.net Sent: Thursday, May 26, 2005 5:09 PM Subject: Re: [AMRadio] Globar brand thermistors Yea, when Jim reminded me of those globars, I realized that would be perfect to slow down the current surge on my my old radio with the 117Z6 rectifier, that lights up like a light bulb when you first turn it on! That's gotta shorten the life of the tube, big time! In my mind's eye, I could see one of those globars, still in the card, someplace in all my old TV krap that I never threw away. The question is - can I find it? So I headed out to my storage area, rumaged around, found my old tube caddy, and found the globar, still in it's wrapping, just like I saw it in my mind's eye. Way Kool! 73, George KE4HJ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
