[Amps] bad 572B's

[Carl]

There is the Svetlana 572B 572-160 with a plate cap that is for RF and 
audio. They have a smaller anode area than Cetron and Chinese and have been 
out of production for years.

The 572-3, 572-10, and 572-30 without the plate cap are an audio tube and 
also no longer in production.
They were not actually built by Svetlana but another Russian company.

Carl
KM1H


----- Original Message ----- 
From: "kingwood" <k5jv at kingwoodcable.com>
To: "Amp Reflector" <amps at contesting.com>
Sent: Saturday, March 23, 2013 11:39 AM
Subject: [Amps] bad 572B's


> Greetings to all,
>
>        Last week, I received a case (10 tubes) of new Chinese 572B tubes 
> from a distributor that I have bought tubes from for over ten years. 
> These tubes were new, from the latest production.  I plugged two into a 
> SB-200 and was disappointed to see a bit less than 50 % of the expected 
> power.  I tried another pair and got the same results.  I went through the 
> entire case and found them all to be way, way, down in emission, but, I 
> must say, they were extremely well balanced.  HI Hi
>
>        I had a pair of 572B's, from the same source, that I bought about 
> two years ago, in another amp.  I plugged them into the test amp and got 
> the normal, expected, output.  The entire case of new 572B's went back to 
> the distributor.  I wonder if they mixed up some low Mu tubes with their 
> Hi Mu, 572B's at the factory.
>
>        There was some discussion about the Svetlana the 572-160, in one 
> post. They are excellent tubes for audio work.  They have, basically, the 
> same internal structure (large graphite anode) as the 572B, but, without a 
> plate cap, they would not be an simple job to install them in an SB-200, 
> FL-2100, or Ameritron amp.  But, for the AM'ers,  they make a great 
> modulator tube.
>
> 73 de Lon, K5JV
>
> Lon W. Cottingham
>
> 1110 Golden Bear Ln.
> Kingwood, TX 77339
>
> 281-358-4207
> 281-795-1335 Cell
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