The 572B works just fine on 6M at full ratings. This is been discussed many
times on here and should no longer be an issue.
Carl
KM1H
----- Original Message -----
From: "bill price" <kingofbackswing@hotmail.com>
To: <n1miw@cox.net>; <amps@contesting.com>
Sent: Sunday, August 09, 2009 9:21 AM
Subject: Re: [Amps] SB-200 6 meter conversion
the 572b tube is not rated to operate on 6 meters, the sb220 would be a
better choice.
i have a sb200 with a gi7b tube that some one started to mod and gave up,
this fall i will finish it. bill nj2s
> From: n1miw@cox.net
> To: Amps@contesting.com
> Date: Sat, 8 Aug 2009 22:34:18 -0400
> Subject: [Amps] SB-200 6 meter conversion
>
> I just wanted to report that I have been almost successful at converting
> my SB-200 with 572B's to 6 meters. I originally wanted to replace the tube
> with a GI-7B (and still may do so), but decided that I should give it the
> effort to at least try the 572's to "see what happens". I removed several
> plates from the tune cap and at the moment, I have a jumper on the output
> coil at the 1 turn mark - this coil looks like it "might" be original, but
> not sure since this amp was previously modified for ...ahem... 11 meters.
> With 30 watts in, I'm seeing ~500 watts out on the bird. Not sure about
> the
> accuracy though because the slug I'm using is for 2-30MHz. I plan on
> connecting up the amp to the digital wattmeter tomorrow to see how close I
> actually am to the 500 watt mark - it's getting late. I'm also hoping the
> signal is clean - I don't have an analyzer. Guess some on-the-air testing
> is
> needed during off-season.
>
> One quick question for you guys who are running modified 6 meter amps -
> does the amplifier draw more line current after the mod? I seem to have
> allot of output for little input, and when I approach 70 watts in, I run
> the
> risk of tripping the breaker in the house. I'm happy with the 500 watts
> (if
> accurate), but wanted to hear someone else's experience.
>
> Oh, by the way - I didn't touch the suppressors on the anodes. They're
> still 3 turns around a 47 Ohm Carbon Comp resistor. I have ~300ma grid
> current with ~500ma plate current at 500 watts output.
>
> 73's... Larry N1MIW
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_________________________________________________________________
Express your personality in color! Preview and select themes for Hotmail®.
http://www.windowslive-hotmail.com/LearnMore/personalize.aspx?ocid=PID23391::T:WLMTAGL:ON:WL:en-US:WM_HYGN_express:082009
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|