[Amps] 3CX1500A7/8877

[Gudguyham at aol.com]

BILL , a long time ago I experimented with the GS-35B  tube like  you.  
When it first hit the street here after the cold war I experimented  by putting 
one in place of an 8877 in an AL-1500.  As our Comrade eludes to  it's kin 
to the 8877 I just had to do this.  Here is the result.  With  100 watts 
drive in an AL-1500 the 8877 will make 2300 watts output.  Once I  switched the 
GS-35B in there I could only get 1600 max. So as you discovered I  did too. 
It is simply not the same thing at all.  That experiment turned me  away 
from them for good.  I'd take a $300.00 medical pull 8877 any day over  a 
$150.00 GS-35B.
 
 

Curious:  Was that a tuned input or a swamped resistive  type?

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original  Message----- 
From: Bill, W6WRT
Sent: Monday, July 30, 2012 2:24 PM
To:  AMPS
Subject: Re: [Amps] 3CX1500A7/8877

ORIGINAL MESSAGE:
On Mon,  30 Jul 2012 08:03:41 +0300, Alex wrote:

>Russian GS35b triode is close  to 8877 and works up to 1000MHz and able
>to  run 1.5kW easy with 3kV  plate voltage.

REPLY:
GS35b's work but they are relatively  inefficient, IMO. I built an amp and
swapped between a GS35b and an 8877. In  order to get 1500 watts of carrier 
out
of the GS35b, I had to drive it  till the DC input was 3000 watts, an 
efficiency
of 50%

I then  changed the socket and filament voltage and put in an 8877. Now to  
get
out 1500 watts, I only had to drive it till the DC input was 2500  watts, an
efficiency of 60%. And the drive power required dropped from about  85 
watts 
down
to about 45.

In both cases, I used two different  tubes, all four were brand new.

One other European ham confirmed he had  about the same results.

You pays your money and you takes your  choice.

73, Bill  W6WRT
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