[Amps] Tube choice for SB-200 on 6 meters

[Carl]

As designed in the 60's its a 1 KW INPUT amp with roughly 600W expected 
output.

Original somewhat leaky filter caps and their equalizing resistors put extra 
load on the transformer.

Harbach sells a new fan with a higher speed motor and a new PS board kit 
thats a bargain.

Once a properly converted amp is tuned up at 50.2 there is no need to touch 
it again when operating 50.0 to 50.4 unless tubes or antenna are changed. 
Some people take forever to tune and are always messing with it. WRONG!

Ive run a 200 for a typical weekend in contests or 3-5 hours straight on CW 
during DX openings at 700W out. For digi modes keep it down around 450-500W 
and give it a break once in awhile. Reduce power ONLY by reducing drive; 
dont mess with the Load control.

Its no different than running most amps in digi modes at full bore on HF; 
some just wont take it. And that includes some Alpha's.

Over the decades Ive noticed that most hams dont know how to tune and use 
any amp.

Carl
KM1H



----- Original Message ----- 
From: "David Craig" <davidhcraig at verizon.net>
To: <n1miw at cox.net>; <Amps at contesting.com>
Sent: Saturday, July 11, 2009 12:42 PM
Subject: Re: [Amps] Tube choice for SB-200 on 6 meters


>    I'll defer to the comments of others on the 572b insofar as stability 
> at
> 50 MHz is concerned.  One thing however is a virtual certainty- 572b
> conversions (at least SB200s) do not hold up with hard duty-cycle use such
> as digimodes or contest-style operating at 50 MHz.  Be it the inadequate 
> PS,
> the tubes, or whatever, regardles of the style of monoband conversion it
> needs to be treated with kid gloves.  If it is all you can do, then I'd 
> say
> go for it as it is better than nothing, but don't hit it too hard.  73 
> N3DB
>
>
> ----- Original Message ----- 
> From: "Larry" <n1miw at cox.net>
> To: "'Carl'" <km1h at jeremy.mv.com>; <Amps at contesting.com>
> Sent: Saturday, July 11, 2009 10:59 AM
> Subject: Re: [Amps] Tube choice for SB-200 on 6 meters
>
>
>> The problem I have is that I do not know what I am doing with these tubes
>> for this conversion. I have yet to come across a conversion that 
>> everybody
>> agrees with. I don't want to be a "hack", I just want to get an amplifier
>> on
>> the air for 6 meters, do it myself, and not spend an arm & a leg getting
>> it
>> there. The amp I have was purchased for the right price - I wish it was
>> the
>> 220 that I had, because of the tubes. However, since I don't, unless
>> someone
>> can tell me how to do the conversion SAFELY, I would just prefer to 
>> change
>> the tubes to ones that are rated OK at 50MHZ. Larry N1MIW
>>
>> -----Original Message-----
>> From: Carl [mailto:km1h at jeremy.mv.com]
>> Sent: Saturday, July 11, 2009 9:26 AM
>> To: n1miw at cox.net; Amps at contesting.com
>> Subject: Re: [Amps] Tube choice for SB-200 on 6 meters
>>
>>
>> Obviously I do not want to use the 572B's because of the controversy
>> surrounding them at this frequency. TIA... Larry N1MIW
>>
>>
>> There is no controversy among those that know what that are doing. Only
>> the
>> hacks blow them up and then send the amp to me or others to be done 
>> right.
>>
>> Carl
>> KM1H
>>
>>
>>
>>
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "Larry" <n1miw at cox.net>
>> To: <Amps at contesting.com>
>> Sent: Saturday, July 11, 2009 12:34 AM
>> Subject: [Amps] Tube choice for SB-200 on 6 meters
>>
>>
>>> Hello group,
>>>
>>>   I'm looking for some information on converting an SB-200 to 6 meters. 
>>> I
>>> originally thought about using the Russian GI-7B tube, but now I'm not
>>> sure.
>>> It looks like I can only use one tube due to power supply limitations.
>>> What
>>> have you guys seen in real-world conditions if you used this tube? Will 
>>> I
>>> see about 500 CLEAN watts out from the single GI-7b (someone said in the
>>> archives that one of these tubes equals 2 572B's)? Can I use 2 GI-7b's
>>> without letting the smoke out of the transformer or PS? There's also the
>>> mod
>>> for the GLA-1000 where the output watts is ~750 which I'm using for
>>> comparison, but I don't know what the current was at that limit. The 
>>> spec
>>> sheet for the GI-7b might put the current for 2 tubes at close to 1A,
>>> which
>>> the SB-200 can't supply as far as I know.
>>>
>>>   If the single or dual GI-7b can't give me 500 watts+ out from the
>>> SB-200
>>> PS, is there another tube (or tubes) of choice you would recommend for
>>> the
>>> SB-200? Obviously I do not want to use the 572B's because of the
>>> controversy
>>> surrounding them at this frequency. TIA... Larry N1MIW
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>
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