[TenTec] Centaur Tubes odd ones in parallel

[Mike Schatzberg]

Actually, I tested many of his concepts on my SB 220 which I built around 1967 or so. I do not ascribe to them all. His theory on VHF parasitic oscillation has remained a topic which is still controversial and debated to this day. 

I did discovered something of interest to perhaps only myself when I read last night his circuit improvements compendium on the SB 220. He had changed the wattage of his grid equalization resisters to 1/2 watt and added some dissipation protection as well. 

I wrote to Mr. Measures years ago, regarding his grid fuse concept, which he advocates for additional tube protection. I told him that the original wattage he used, 1/4 watt I think, was really too low. I also told him that I generally thought that resisters make poor fuses even if they are flameproof. 

I recommended that the value be changed to a 1/2 watt, and forget the grid fuse concept and just go with RF negative feedback and grid equalization which I had decided to use. 

Well, last night that is what I found in his circuit description. While he still talks about grid fuses, they will not open without being seriously over driven. 

My SB 220 was a great test bed for lots of experiments. Many of the concepts were so easy to apply and evaluate. My own QSK systems that I use today on many ceramic triode conversions were adopted from my Heathkit test bed. I have modified many models of Alpha and Commander amplifiers which are in use in many places today. 

As they say, one well designed experiment is worth a hundred expert opinions. I generally don't offer opinion but rather test results. 

Sorry for the bandwidth. I know the moderator will be tolerate however.

73 and Happy DXing,

Mike 
W2AJI
Owner Ten Tec Reflector 
Owner Orion 565/566 Reflector
Owner 1000MP Reflector 


Sent from my iPhone

> On Apr 2, 2015, at 9:07 AM, Rick - DJ0IP / NJ0IP <Rick at DJ0IP.de> wrote:
> 
> Hi Tony,
> 
> It's W2AJI.
> He pointed out work that Rich Measures had done on this topic.
> Specifically it was, "High Speed Switching / QSK for the TL-922 and SB-220
> With Circuit Improvements for the TL-922" 
> Here: http://www.somis.org/QSK922.html 
> 
> The topic was using non-matched tubes in a multi-tube linear amp.
> Scroll down a ways until the paragraph on ANODE AND GRID GLITCH PROTECTION.
> 
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
> 
> 
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Tony
> Sent: Thursday, April 02, 2015 4:51 PM
> To: Rick - DJ0IP / NJ0IP
> Subject: Re: [TenTec] Centaur Tubes odd ones in parallel
> 
> Rick ,
> Who's this Mike? Does he have a website?
> 73, Tony VE3DWI.
> 
> Sent from my BlackBerry 10 smartphone on the Bell network.
>   Original Message
> From: Rick - DJ0IP / NJ0IP
> Sent: Thursday, April 2, 2015 04:08
> To: 'Discussion of Ten-Tec Equipment'
> Reply To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Centaur Tubes odd ones in parallel
> 
> Well done, Wade!
> As Mike showed us, it indeed can be done that way.
> 
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)