[Heath] Concerning the SB-200 and tubes...

[Kenneth G. Gordon]

On 19 May 2014 at 10:12, Guy Giacopuzzi wrote:
 
> As a collector, I can't believe we're having this discussion...

Oh? Why is that, Guy?

> the 572-B is very
> reliable if not pushed to the limit...

The OLD ones were: these "new" Chinese-made sub-copies are not. They 
are total crap.

>if you run these tubes at about 500 watts
> output, they seem to last forever, at least with the three 200's that I own...

I own two SB-200s. The amplifier itself is VERY reliable and a most excellent 
small amp. However, I repeat, after two years of very intensive research on 
the subject, and several hundred dollars spent, I can absolutely assure you 
that the modern Chinese-made "572B" tubes are total junk. They are 
BARELY useable.

Without good tubes, the amp is as worthless as though it had NO tubes. It is 
nothing but a pretty, green door-stop.

>.I
> for one would scour the internet,

I did that. No joy.

> or wait for RF Parts to come up with a
> supplier...

Which only came about within the last few months. What was I supposed to 
do with my SB-200s in the meantime? Set them on the shelf and do without? 
I can't do that. My only antenna is very poor, and I have a very heavy 
schedule in NTS and TCC handling traffic. I use my amp, heavily, every day. 
The Chinese-made so-called "572B" tubes last, at most, 6 months, and I 
really do baby them. I never allow more than 35 mA per tube of grid current. I 
never allow more than 500 watts output. I never overdrive them. I turn the 
amp completely off when it isn't being actively used in order to save what little 
filament emission is there. Yet they last, at most, 6 months. My most recent 
set of NEW Chinese-made so-called "572B"s lasted 4 months.

I repeat: I have NEVER had so much as a minor problem from the SB-200 
itself. Every problem I have had has been with these crappy Chinese-made 
substitutes for REAL 572Bs.

So, Guy, do you have a better idea of what to do with my SB-200s if there are 
no more 572Bs? What would YOU do if GOOD 572Bs were absolutely no 
longer available?

Why do you think I am absolutely ecstatic over RF Parts Co project to MAKE 
a manufacturer build quality 572Bs?

Gee...

I am poor, retired, have a family to take care of. I am not going to spring over 
$1K for a new amp. I'll use and if necessary modify what I have. Or build one 
from war surplus parts.

>.Ask yourself the question...if you were looking for an SB-200 to
> buy, would you buy an original or a modified unit....

I wouldn't care, if it was cheap enough. I can take care of almost every 
problem I run into, and have done so. I am not a collector: I am a USER.

In addition, I most certainly never intend to sell my amps to anyone.

Gee.... :-(

Ken W7EKB