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Post subject: RCA 6v6 Tube help
Posted: Wed Feb 06, 2019 2:12 pm
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I am looking at 2 RCA 6V6GTA Vacuum Tubes - 1960's on Ebay I do not own a Hickok TV-7D/U the add says
These lightly used tubes have been tested for mutual conductance. On my Hickok TV-7D/U tester they read 84 and 84. A reading of 46 is the minimum recommended.
not sure what this reading means to them, if you know let me know
mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Wed Feb 06, 2019 2:28 pm
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Sorry, tube tester are not 100 % reliable.
I have a good one.

Reading 84 mean tubes are more weak than strong.


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Post subject: Re: RCA 6v6 Tube help
Posted: Wed Feb 06, 2019 3:12 pm
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stratele52 wrote:
Sorry, tube tester are not 100 % reliable.
I have a good one.

Reading 84 mean tubes are more weak than strong.

Thanks for the reply. I own a ecco 166 tube tester and not familiar with the Hickok TV-7D/U. I am also tired of getting weak or not close to matching tubes from ebay. Yes I am aware that tube testers can only tell you so much the proof is in the Amplifier

mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Wed Feb 06, 2019 4:28 pm
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I am going to pass on the first one. Can anyone give me your thought on this pair
Image
mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 8:22 am
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Mud, in layman's terms GM is a measure of electrical efficiency(how intact the plate coating is). The GM measurement or transconductance is a ratio of small change in plate current to a small change in grid voltage that produces it, with all other electrode voltages maintained at constant.
Every tube tester has a scale from 0-100, but the baseline parameters(plate voltage, cathode, heater, etc.) are very different from tester to tester. They each also have a good-no good number and very tester to tester.
Tube testers do not test at amplifier voltages in most cases.
The TV7 is a respectable machine for testing, was what the military used.
If 46 is the good-no good number, generally 2x or 92 is 100% and 84 is therefor a 91% tube.
I usually buy based on visual inspection, then reported data, then price from ebay.
original box- preferred
pins- straight, minimum oxidation
labeling- intact tube identifier, manufacturer specific, codes
flash integrity- no rainbows, see through spots
base- heavy scratched, light or none
hope this helps


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 9:10 am
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How much the seller ask ?
For $10 each why not , for more I'll give up


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 2:17 pm
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sfceric64 wrote:
Mud, in layman's terms GM is a measure of electrical efficiency(how intact the plate coating is). The GM measurement or transconductance is a ratio of small change in plate current to a small change in grid voltage that produces it, with all other electrode voltages maintained at constant.
Every tube tester has a scale from 0-100, but the baseline parameters(plate voltage, cathode, heater, etc.) are very different from tester to tester. They each also have a good-no good number and very tester to tester.
Tube testers do not test at amplifier voltages in most cases.
The TV7 is a respectable machine for testing, was what the military used.
If 46 is the good-no good number, generally 2x or 92 is 100% and 84 is therefor a 91% tube.
I usually buy based on visual inspection, then reported data, then price from ebay.
original box- preferred
pins- straight, minimum oxidation
labeling- intact tube identifier, manufacturer specific, codes
flash integrity- no rainbows, see through spots
base- heavy scratched, light or none
hope this helps
Thank for the explanation yeah it not a lot of fun buying tubes from eBay, sometimes I think they sell them knowing you may send them back on your own dime and they have already made 5 to 7 dollars on shipping do that enough times and it will add up, worst case scenario the buyer just may keep them
mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 2:18 pm
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stratele52 wrote:
How much the seller ask ?
For $10 each why not , for more I'll give up

Seller wants $50 USD plus $7 shipping, I will pass
Thanks
mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 2:39 pm
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mud wrote:
stratele52 wrote:
How much the seller ask ?
For $10 each why not , for more I'll give up

Seller wants $50 USD plus $7 shipping, I will pass
Thanks
mud


For a pair of matched (performance and date) gray-plate RCA's?

:shock:
I'd be all over those.

Bolo badge for you, troop.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 3:08 pm
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Retroverbial wrote:
mud wrote:
stratele52 wrote:
How much the seller ask ?
For $10 each why not , for more I'll give up

Seller wants $50 USD plus $7 shipping, I will pass
Thanks
mud


For a pair of matched (performance and date) gray-plate RCA's?

:shock:
I'd be all over those.

Bolo badge for you, troop.

Arjay

I took your advise, let the dice roll, will know in a few days how well matched they are
mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 4:51 pm
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Yeah, post an AAR once you've had a chance to check them out in an amp.

A Princeton Reverb or a Deluxe Reverb, I presume?

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: RCA 6v6 Tube help
Posted: Thu Feb 07, 2019 5:30 pm
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Yeah I agree for $50 its a decent buy and if the data is correct they are w/in .5ma of each other.
As for flea bay, it can be a crap shoot and usually single tubes can be bought on the cheep. The last single I think I paid $10 bucks for it was NOS, the last matched pair I paid $90 for vt107a's.
Although part of the so called fun of ebay is the searching.
I have a few saved searches that I frequently look at to find deals here and there and people I've bought good items from saved that I search there stock listings if I find myself in need of something. Both of those help save a little time and money. Always good to shop when you don't need stuff, you can bid lower and not be to concerned if you loose an item to a higher bidder.


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Post subject: Re: RCA 6v6 Tube help
Posted: Fri Feb 08, 2019 1:36 pm
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Retroverbial wrote:
Yeah, post an AAR once you've had a chance to check them out in an amp.

A Princeton Reverb or a Deluxe Reverb, I presume?

Arjay

Absolutely and it is for the Princeton Reverb
mud


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Post subject: Re: RCA 6v6 Tube help
Posted: Fri Feb 08, 2019 2:04 pm
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Outstanding. Those new bottles will feel right at home.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: RCA 6v6 Tube help
Posted: Fri Feb 08, 2019 2:23 pm
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sfceric64 wrote:
Yeah I agree for $50 its a decent buy and if the data is correct they are w/in .5ma of each other.
As for flea bay, it can be a crap shoot and usually single tubes can be bought on the cheep. The last single I think I paid $10 bucks for it was NOS, the last matched pair I paid $90 for vt107a's.
Although part of the so called fun of ebay is the searching.
I have a few saved searches that I frequently look at to find deals here and there and people I've bought good items from saved that I search there stock listings if I find myself in need of something. Both of those help save a little time and money. Always good to shop when you don't need stuff, you can bid lower and not be to concerned if you loose an item to a higher bidder.

For $50 and if the data is correct ( Thanks to all who helped there) I will give it a shot. I do have working tubes in there now that are matched, new production EH and they sound pretty good, but as an audio guy I am always striving for a better sound. I am always moving preamp tubes around looking to hear a difference or something sweeter and I have quite a lot of them, most are USA made RCA, Tung-sol, Raytheon, GE, and a bunch of GAP/R (George A Philbrick Researches 12AX7) I think the GAP/R are rebranded Tung-sol. I lack power tubes in abundance, I do have mismatched 6V6, and they do fine in my Vibro Champ, as I only need one at a time. Now for the little wait they should arrive next week
mud


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