[Boatanchors] Fw: 1625 tube(s)

[KEN]

----- Original Message ----- 
From: "rbethman" <rbethman at comcast.net>
To: "KEN" <n5cm at rtconline.com>
Sent: Wednesday, March 23, 2011 12:11 PM
Subject: Re: [Boatanchors] 1625 tube(s)


> Hi Ken!
> 
> I was just posting the best info I could dig up and find!
> 
> You're rig shames me.  I haven't built anything except a linear 
> amplifier using a pair of GG 813s!  That was ages ago.  The "movers" 
> managed to shorten the SX-28 cabinet I built it in by over 1 1/2 
> inches.  It pretty sell tore it up.  Filing a claim on it with Uncle 
> Sam, required me to turn it in to get the claim paid/settled.  They told 
> me to pick out an "equivalent" to determine the "value".  Since I was 
> sitting in Korea, I used a Heathkit catalog.  The closest thing was the 
> SB-201.  I gave them the cost and the shipping.  The paid it.
> 
> Oh well.  Now I'm and avid AM type, and have an HT-32, SX-101MkIII, a 
> DX-60 w/HG-10, a BC-610, a T-213, a Northern Radio SP-600, and an R-390A 
> in stages of restoration.
> 
> That about covers it!
> 
> Bob - N0DGN
> 
> On 3/23/2011 12:58 PM, KEN wrote:
>> Hi Bob,
>>
>> Back about 1946 I built up a driver and final liner amp using 1625's.
>> I found a Central Electronics 10B "exciter" with 10 watts peak to peak
>> output. 1625's back then were 25 cents apiece, new in box. I built up
>> an amplifier using four 1625's in parallel grounded grid! The 10B did 
>> not have enough power to drive the grounded grid stage,
>> so I put in a single 1625 driver stage also grounded grid.
>>
>> There is a method of changing the tubes to change the suppressor grid
>> from the grounded connection to a blank pin next to it thus making
>> possible grounded grid configuration. Some brands of tubes could not
>> be modified because the suppressor grid was connected inside the
>> glass envelope. The RCA was one brand that could not be modified.
>>
>> I used this set-up for many, many years with  excellent results!
>> One ham, after bragging on my audio quality, when I told him I was
>> usihg a grounded grid driver to drive four in a grounded grid final,
>> said "you can't drive a grounded grid stage with a grounded grid
>> driver stage"! Well, I said, 'You're listening to it!"
>>
>> I still have the old homebrew in storage.
>> Take care,
>>
>> Ken   N5CM 
>