Mike, I agree with you.
Far too many people talk only theory here, without actually "doing".
I generally only write about things I have done myself.
I was surprised to hear you had to modify the Commander.
I thought they were pretty good amps by design.
Very similar to my old QRO Technologies amps.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Mike
Schatzberg
Sent: Thursday, April 02, 2015 6:13 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Centaur Tubes odd ones in parallel
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@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@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)
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