[Amps] SB-200/572B issues

[cemilton at aol.com]

 GA Larry,

I recently restored an SB-200 and have since sold it to a local ham friend who is getting full power on all bands and the rig is doing what Heath said it would.? They are great little desk top amps.? And not complicated at all.

I'm no expert.........in anything............but will attempt to help a fellow ham if I can.? Why not contact me off the list if you like and I'll see if I can offer a couple of suggestions.? As for tubes..........these days it can be a crap shoot.? To blanket state that all Chinese tubes are bad isn't true.? But like rotten apples in a barrel, it only takes one (the one you personally own) to go south and you're still in trouble.? Filament sags on horizontally mounted tubes such as the 572B's and the 811's (my 30L-1 uses these) can occur and make for a fine light show.

You've piqued my interest by commenting about the use of an SA-2060 with the amplifier.? 

Drop a line.

73 
W4MIL
Chuck


 


 

-----Original Message-----
From: Carl <km1h at jeremy.mv.com>
To: n1miw at cox.net; Amps at contesting.com; cemilton at aol.com
Sent: Wed, 12 Nov 2008 10:41 am
Subject: Re: [Amps] SB-200/572B issues










----- Original Message ----- 
From: <cemilton at aol.com>?

To: <tjjapha at earthlink.net>; <n1miw at cox.net>; <Amps at contesting.com>?

Sent: Wednesday, November 12, 2008 10:19 AM?

Subject: Re: [Amps] SB-200/572B issues?
?


>?

> Looks like he is N1MIW and his name is Larry..................?

>?

> Could be wrong................his questions appear valid.?

>?

> What's missing??
?


Any semblence of coherence. He posts these long rambling messages on 
another site also.?
?

IMO his only solution is to either send the amp to someone that knows 
what they are doing or sell it as is and buy one that is working.?
?

With a couple of sets of tubes already destroyed and who knows what else 
he is out of his depth IMO and just getting in even deeper. Those who 
tried to help him  before have given up responding.?
?

Carl?

KM1H?
?

>?

> 73?

> Chuck?

> W4MIL?

>?

>?

>?

>?

>?

>?

>?

> -----Original Message-----?

> From: ANTHONY JAPHA <tjjapha at earthlink.net>?

> To: me <n1miw at cox.net>; Amps at contesting.com?

> Sent: Wed, 12 Nov 2008 9:59 am?

> Subject: Re: [Amps] SB-200/572B issues?

>?

>?

>?

>?

>?

>?

>?

>?

>?

>?

> Why should anyone, even on a helpful site like this one, read an?

> essentially anonymous post??

>?

>?

>> [Original Message]?

>> From: me <n1miw at cox.net>?

>> To: <Amps at contesting.com>?

>> Date: 11/11/2008 7:19:41 PM?

>> Subject: [Amps] SB-200/572B issues?

>>?

>>    Hello group. I'm trying to find the answer to why I'm having so 
>> much?

>> trouble with my amplifier, but not having much luck.?

>> The SB-200 performs well on 80, 40 and 20. However, on 15, it will 
>> not?

> tune?

>> properly - I may have a problem with the input circuit. My biggest 
>> problem?

>> is on 10. Yesterday, I tried to tune on 10, but I can get only 50 
>> watts?

> out?

>> for 100 in. I had the AG6K parasitic suppressors installed, took them 
>> out,?

>> and re-installed the original Heathkit suppressors which resulted in 
>> only?

>> 200 watts out. A big increase, but not near what the amp should be?

>> producing. Now, while I could tune for 200W, if I turned the "load" 
>> past 6?

>> on the scale, the amp would begin to peg the forward and reflected 
>> power?

>> needles on my SA-2060 tuner. The tubes I'm using are Taylor brand 
>> from RF?

>> Parts - received in August. I also had a pair of Chinese tubes which 
>> had a?

>> failure (filament went open). Is this "pegging" of the needles an?

>> oscillation? I can actually get the amp to do this without any RF 
>> input.?

> The?

>> Taylors failed last night on me while sitting idle - taking out the 
>> power?

>> supply. My first set of Taylors had failed too, but there wasn't any?

> further?

>> damage. Are the Chinese making tubes of such poor quality lately? 
>> While?

>> tuning up, if I saw any more than a dull red glow from the tubes I'd 
>> stop?

> &?

>> let them settle for a couple of minutes. My plate voltage is 2250V. 
>> On the?

>> lower bands, the plate current was 400ma, grid current was 250 - 
>> 300ma. On?

>> 10, the plate current was 400-450ma, but the grid current was only?

> 150-200ma?

>> with 200 watts out (if I remember correctly). The bias voltage 
>> is -133V?

>> standby, and -1.99V keyed. I even dropped the filament voltage to 
>> 6.15V?

> from?

>> 6.45V to try to keep everything in check.?

>>?

>>    When I get the oscillation & watch those needles move, I can 
>> "play"?

> with?

>> how much they deflect using the "load" knob. If I do this with the 
>> amp?

>> keyed, but no RF input, there's an increase in receiver noise, and 
>> the?

> more?

>> the needles are deflected, the more noise in the radio. This noise 
>> has?

> also?

>> taken out an automatic antenna tuner on me that was between the radio 
>> and?

>> amplifier, so whatever it is, it's harmful! Hoping someone here can 
>> help.?

>> ...Larry?

>>?

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