[BULK] - Re: [Amps] 4-400A and QB4-1100 amp - TSPA

[Steve Katz]

Bill, I think you'd have to do more than that.  I had a T-bolt for many
years back in the late 60's/early 70's and thought about increasing plate
voltage....then reconsidered when I looked at the plate tank components.
Seemed to me everything was too close-spaced to support higher voltage
operation.  -WB2WIK/6

"There is no reason anyone would want a computer in their home." - Ken
Olson, Chairman & Founder, Digital Equipment Corporation (1977)

> -----Original Message-----
> From:	Bill Fuqua [SMTP:wlfuqu00 at uky.edu]
> Sent:	Wednesday, September 01, 2004 8:59 AM
> To:	John T. M. Lyles; amps at contesting.com
> Subject:	[BULK] - Re: [Amps] 4-400A and QB4-1100 amp - TSPA
> 
> That gives me an idea. I have a Thunderbolt and if I go to solid state 
> rectifiers, a capacitive input filter and then wire up the 866A's in 
> parallel but in series with the filtered  output I would still have the 
> light show and more output. Just have to have higher voltage filter 
> capacitors and bypass the filter choke.
> 
> 73
> Bill wa4lav
> 
> 
> At 09:17 AM 9/1/2004 -0600, John T. M. Lyles wrote:
> >The 1960 vintage Heathkit Chippewa amplifier model KL1 was a dual 4-400A 
> >amplifier which worked well in class AB1. It was described in Electric 
> >Radio magazine a few years back, with some modifications to improve it. I
> 
> >believe that there is an online index to ER which you can look up, and 
> >order a back issue. I believe that earlier W6SAI Radio Handbooks (like 
> >21st edition) elaborated on the craft of building tetrode amplifiers. 
> >About that time the 3-500Z was really becoming a favorite, as a grounded 
> >grid zero bias (low bias) class B amplifier. Setting up tetrodes for best
> 
> >IMD and linear operation requires a bit more care, as you have both a 
> >screen and control grid bias voltage to deal with. Some have found that 
> >grounding the grid and screen for RF (and applying the DC bias to both) 
> >and driving the cathode is a good way to handle a 4-400A. The Johnson 
> >Thunderbolt amplifier had 4-400As but it ran them in AB2 at too low an 
> >anode voltage, leaving it short of output and prone to being overdriven 
> >(causing IMD).
> >
> >I have a Chippewa that I am going to restore someday, as it got
> "modified" 
> >by someone. I saw another one that had been converted to grounded grid, 
> >but wasn't interested as it had been too modified from original, and for 
> >that an SB220 or Drake L4 would be adequate. Problem with Chippewas is 
> >that they had a separate huge power supply chassis with 866As and it is 
> >usually missing or burnt up.
> >
> >73
> >john
> >K5PRO
> >
> >
> >
> >>Message: 1
> >>Date: Tue, 31 Aug 2004 18:23:08 +0200
> >>From: "ON5KM" <on5km at planetinternet.be>
> >>Subject: [Amps] search 7527A design
> >>To: <Amps at contesting.com>
> >>Message-ID: <005601c48f76$d160a020$a284efd4 at computer>
> >>Content-Type: text/plain;       charset="iso-8859-1"
> >>
> >>hi ,
> >>who has a link or info to a good stable design using 1 or 2
> >>7527a's (qb4-1100 or 4-400) ??
> >>all info welcome .
> >>tnx on5km stef
> >_______________________________________________
> >Amps mailing list
> >Amps at contesting.com
> >http://lists.contesting.com/mailman/listinfo/amps
> 
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps