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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 3:12 am 
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Location: Milwaukee,WI
I've got one of those older Tripp-Lite models but always used my newer, cheaper inverter because I figured the old one was not only heavier but less efficient and would drain my battery faster. Maybe its time to blow the dust off of it because my newer inverter has an overactive current sensor and shuts down with too many radios at startup.


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 4:15 am 
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Joined: Aug Wed 24, 2011 4:35 am
Posts: 4170
Location: Sunnyvale CA
allied333 wrote:
pixellany wrote:
Quote:
Im sure it has something to do with the 60 hertz not being there when using the inverter.

That has nothing to do with it .....electrical apparti don't work because of 60Hz power......they work IN SPITE OF IT.

Wasn't it Westinghouse that wanted the power grid to be DC?----would have made radio design easier.....

That was Edison. DC could only travel about 5 miles. Edison was way off base here. A power plant every 5 miles?



At the time. Now, it makes sense for some long-distance power transmission to be done by very high voltage DC, and there are plenty of examples in operation.

Brett


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 4:37 am 
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Joined: Dec Sat 24, 2011 9:17 pm
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Location: Vancouver Island, Canada
Kennynva wrote:
I was watching the movie "The day after" a 1983 movie where an the world launched all there nuclear bombs, and in the hospital, someone found a tube radio in the basement, and they hooked it up to an 12 volt inverter to power the radio, and that made me think about it..
I really didnt think it would work..

Someone on above, ask me what Im inverting..and it's 12 DC to 115 AC.

KNY
I had one of those inverters in the 1980's, but never tried to power a tube radio. I recall that it was an empty black box with a few solid state components and a red light.

The premise of the movie was that nukes destroyed all the digital devices but not the tube radio, is this right? Nukes would have destroyed the ICs in the inverter as well, no? :lol: So they must have found an old one that put out a nice clean sine wave.

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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 5:56 am 
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Joined: Dec Tue 08, 2015 12:53 am
Posts: 391
Location: shirley NY...Long Island
I dont know if an EMP bomb would go all the way to a basement of a hospital or school fallout shelter...but you are right..it would not work if it had IC's in it...

Kenny


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 3:27 pm 
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Joined: Jan Mon 04, 2010 2:52 am
Posts: 2604
I have two Cyber Power 550VA inverters, but these were specifically designed to serve as backups for desktop computers in the event of a power failure, In that capacity, they serve their purpose. In fact, I did try running a window fan several times off one of them during the hot summer months after a general power failure hit, and the fan would run for 20 minutes before the power finally petered out. Then again, this is relatively a small capacity inverter. This morning, I did try plugging one of my tube radios (Motorola Model 7XM table top radio) into one of those inverters, and the inverter did produce a hum while the radio was on. Then again, there was no claim whatsoever that these inverters would be suitable for such devices.


Last edited by Blustar1 on Nov Tue 13, 2018 5:18 pm, edited 1 time in total.

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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 4:58 pm 
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Joined: Dec Tue 08, 2015 12:53 am
Posts: 391
Location: shirley NY...Long Island
"I did try plugging one of my tube radios into one of those inverters"

In the movie(The day after 1983 on Youtube) at 1:04:15 you see that inverter.


Hi.did you receive any stations in between the hum?


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 5:28 pm 
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Joined: Jan Mon 04, 2010 2:52 am
Posts: 2604
I received a few stations on FM, but none on AM. In addition, I did check the output voltage out of that inverter, and it was approximately 98VAC RMS.


Edit: 93 VAC RMS.


Last edited by Blustar1 on Nov Tue 13, 2018 5:14 pm, edited 1 time in total.

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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Fri 09, 2018 10:27 pm 
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Joined: Dec Tue 08, 2015 12:53 am
Posts: 391
Location: shirley NY...Long Island
Yes just on AM I got no stations, I was wondering if you got any stations. I didnt. and my inverter puts out right at 114 volts.

I am not really worried about it..I just thought about it when I seen the movie...and dont care whether it works or not.

KNY


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Sat 10, 2018 6:21 am 
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Location: Tucson, Arizona U.S.A.
Quote:
I wish they went with 133Hz.... Would make iron core transformers just a tad more efficient.

Not really. The efficiency of a transformer depends on how it is designed. You can design highly efficient transformers and low efficiency transformers for any frequency. The high efficiency ones cost more. 133 Hz would make them smaller, not more efficient.

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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Sun 11, 2018 8:28 pm 
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Joined: Nov Tue 18, 2008 8:34 am
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Location: Hutchinson,Kansas
I have an inverter generator and it wont run tube rigs without noise. It produces terrible line noise as well as RF noise. I made a pig tail with a medical grade electrical filter in it and it helped a lot. Took almost all the noise out of the power and then I run the gen about 50-75 feet away and most tube radios tolerate things just fine. My solid state rigs don't seem to care and work fine.


Todd


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 12:57 am 
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Joined: Aug Wed 04, 2010 5:40 pm
Posts: 325
Location: Tyngsborough, Massachusetts
Jim Mueller wrote:
Edison started out with 55 volt DC systems and found out it didn't work very well. So he doubled it to 110 volts. That was better but there was still too much voltage drop in the distribution system. But about that time the 120 volt AC system came into being and that was the end of any new DC systems for buildings (some railroads still used 600 volt or higher DC systems). Commercial sale of DC power in some cities continued into the early 2000s.

Westinghouse wanted to use 133 Hz power; it was Tesla who insisted on 60 Hz. No one knows the reason for either choice.



With 25Hz lighting had too much flicker, over 100Hz the reactive losses in transmission were too high, 50 to 60Hz was the best compromise.

Jeff


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 4:38 pm 
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Joined: Dec Tue 08, 2015 12:53 am
Posts: 391
Location: shirley NY...Long Island
What decides the hertz in the AC line...??? How did Tesla change that frequency from say 25 hz to 60 or 50 hz?

I tried a halo bolt 58830, its an inverter, that has USB charger, and car battery jump starter, and believe or not..the jump start absolutly works..
The inverter seemed to have less interference, but I have no way to check accurately, im just doing it by sound...it was about 4 feet away..

KNY


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 5:50 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9485
Location: Santa Rosa, CA
Quote:
What decides the hertz in the AC line...??? How did Tesla change that frequency from say 25 hz to 60 or 50 hz?


Power line AC is generated by an alternator... the AC equivalent of a generator. The design and rotational speed determine the output frequency (Hertz). Faster rotation = higher "Hertz."

Image

https://en.wikipedia.org/wiki/Alternator

https://en.wikipedia.org/wiki/Alternato ... 04414u.jpg

Rich


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 6:05 pm 
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Joined: Aug Wed 04, 2010 5:40 pm
Posts: 325
Location: Tyngsborough, Massachusetts
The frequency of an a-c power system is determined by the rotational speed of the generators. A 2-pole machine running at 3600rpm will produce 60Hz power, at 3000rpm it will produce 50Hz.

In the early days of electrification, most utilization was d-c. When a-c began to be adopted for transmission and distribution, rotary converters were used to convert the a-c to the d-c required at the utilization points. High capacity static rectifiers were a long way in the future. Rotary converters are much more efficient on 25Hz than on 50 or 60Hz, so 25Hz was the choice. However, as a-c power started to take over directly as the utilization power it was realized that there was too much flicker in the lighting systems connected to 25Hz systems. There were some trials of frequencies as high as 125 and 133Hz but larger motors weren't happy at those frequencies, and the reactive losses were much higher, so the final result was 60Hz some places and 50 Hz in others.

Jeff


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 6:08 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Beautiful Downtown Burbank CA
What is the Hz of auto alternators, or does it change with rpms?


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 6:32 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9485
Location: Santa Rosa, CA
Auto alternators run at about 400 to 1000 HZ. Frequency changes with speed. You can some times hear the "whine" in your car radio. Frequency doesn't make any difference as alternator AC is changed to DC to power all the car systems and charge the battery. Alternators are 3 phase.

Image

Rich


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 9:13 pm 
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There are a few things at play here.

First, series-string radios (which the presence of a high voltage filament tube like a 35Z5 indicates), are almost always inexpensive designs that have very poor RF isolation from the line cord. Any RF conducted through the line cord will cause some interference. Power transformers provide some extra degree of RF isolation.

The second is that the fast risetimes of the modified sine wave used in inexpensive inverters will make their way into various stages of the radio via capacitive coupling. For fun, I once tried to run a tube amplifier from one of these inexpensive inverters, and I heard an intolerably annoying buzz. I suspect that the buzz was due to capacitive heater to cathode coupling. This amplifier only used six Volt filaments. One can only imagine how bad the buzz coupling might be in a series string radio that has some of its tube filaments riding near 100 Volts with respect to its internal ground return.


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Mon 12, 2018 10:07 pm 
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Joined: Dec Tue 08, 2015 12:53 am
Posts: 391
Location: shirley NY...Long Island
So if I add one of those clamp around ferrite devices, and wrap the 115 volt line around it once..will that help???

KNY


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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Tue 13, 2018 1:05 am 
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Location: Warner Robins, GA
Far as true sinewave inverters go you can build your own quite easily.

The simplest way is to take a car audio amp capable of producing 120Vac on one channel then feed it with an audio generator set for 60Hz which will work for larger loads, but it should only be done where a vehicle can be ran to charge the battery given how much current the amp can draw. Can use a lower powered amp and bridge both channels.

The issue there is that one must keep the power wires supplying the 120Vac from touching the car's ground or the amp might be damaged.

Another option for smaller loads such as one radio is to take a 60 to 100 watt RMS per channel car audio amp and use a 12.6Vac 3A to 120vac transformer or a at least 100 watt 70 volt transformer feeding a 100 to 230 Vac transformer to step up the voltage then use the audio generator to supply the 60Hz sinewave. It is also possible to bridge the amp and use a 25.2Vac 3A transformer and maybe get more power or use just each channel fed by the audio generator and have two inverters.

Same caveat applies about the ground unless the amp grounds one side of the speaker output already and said amp is not bridged.

The benefit there is that now you also have a variable frequency drive in addition to a pure sinewave inverter.

Did just that with a Bogen CHS-60A amp, two transformers and an audio generator.

This is the result. A nice clean sinewave.

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 Post subject: Re: Why I cant use an inverter on a tube radio
PostPosted: Nov Tue 13, 2018 5:13 pm 
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Joined: Jan Mon 04, 2010 2:52 am
Posts: 2604
As I previously posted, I did plug a tube type radio (Motorola Model 7XM table radio) into one of my two Cyber Power 550 VA inverters. However, that particular inverter was only delivering 93.0VAC RMS at the time so that wouldn't have provided a reliable test. In fact, I plugged that same tube type radio into my other Cyber Power 500 VA inverter this morning, and I actually received both AM and FM stations like I normally would. This inverter produced 125 VAC RMS so there was obviously something wrong with the other inverter. In fact, I think that the battery needs to be replaced.


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