[Amps] 3CX1500A7/8877 vs el cheapo GS-35B

[Carl]

            Physical Characteristics
            Envelope  metal-ceramic
            Cooling  forced air
            Minimum required Air flow  2500 l/min (83.3 cfm)**
            Diameter  100.2 mm max
            Length  min 173 max 177mm (6.9")
            Anode Diameter  min 99.7 max 100.2 mm (4")
            Grid diameter min 59.5 max 60.3 mm
            Cathode  indirectly heated, oxide coated
            Cathode Diameter min 40 max 40.5 mm
            Heater Diameter min 25.6 max 26.2 mm
            Weight including copper heatsink 2.8Kg (6.17 lbs)

      **Commonly published data shows 1500 liters/min as 90 cfm but that 
conversion is WRONG. The correct data is 2500 liters/min or 150 cubic meters 
per hour which is 83.3 cubic feet per minute. 90 cfm is still a good target 
number.




----- Original Message ----- 
From: "Bill, W6WRT" <dezrat1242 at yahoo.com>
To: "AMPS" <amps at contesting.com>
Sent: Tuesday, July 31, 2012 12:34 PM
Subject: Re: [Amps] 3CX1500A7/8877 vs el cheapo GS-35B


> ORIGINAL MESSAGE:
> On Tue, 31 Jul 2012 06:43:47 -0400, Carl wrote:
>
>>. I wouldnt want to be in the same room with the blower for one or two
>>GS-35B's.
>
> REPLY:
> I noticed the specs for the GS-35b don't specify a recommended CFM for 
> cooling
> but they do say the maximum temp for cathode and grid leads is only 120 
> degrees
> C. That's pretty low compared to many tubes. A 3-500Z for example is rated 
> at
> 200 C for those same leads.
>
> A builder would be wise to check temps with color-changing crayons or 
> paint.
>
> 73, Bill W6WRT
>
>
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