AW: Heathkit Digest, Vol 14, Issue 27 - Subject: [Heathkit] SB-102 RF voltages

[Peter Hofmann]

Bob,

Concerning the low power/RF voltages on 20m:

1. Adjusting the coil you will find two points (top/bottom of the coil) with
a peak of the power/voltage --> try one and the other
2. If you check the circuit diagram you will see that the 75m coil in the
driver stage (6CB6 -> 6CL6) has two windings (input/output)coupling these
stages
As I remember well the windings on the coil which are leading to next stage
ARE on the bottom side of the coil - and there you have also two peaks, but
with different rf voltages, because of the coupling !!! TRY the adjustment
on both points !!!

Essential and very, very IMPORTANT:

You should start the alignment of the coils beginning with 75m up to 10m
with the indicated (different) positions of the double variable capacitor in
the manual ...

good luck, 73s

de peter oe3pha



> -----Ursprüngliche Nachricht-----
> Von: heathkit-bounces at mailman.qth.net
> [mailto:heathkit-bounces at mailman.qth.net]Im Auftrag von
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> Gesendet am: Montag, 28. März 2005 11:01
> An: heathkit at mailman.qth.net
> Betreff: Heathkit Digest, Vol 14, Issue 27
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> Today's Topics:
>
>    1. Re: SB200 HELP Please (jim u.)
>    2. Re: SB200 HELP Please (Glen Zook)
>    3. SB-102 RF voltages (Robert Nickels)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 27 Mar 2005 07:22:17 -0500
> From: "jim u." <jimbo304 at comcast.net>
> Subject: Re: [Heathkit] SB200 HELP Please
> To: <heathkit at mailman.qth.net>
> Message-ID: <002201c532c7$9efbf400$ef185144 at pentium4>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Digi-Key will sell you any amount, even one resistor if that's
> all you need.
> I think Mouser will also.
> --jim
>
>
> From: <KH6ITY at aol.com>
> To: <heathkit at mailman.qth.net>
> Sent: Saturday, March 26, 2005 9:04 PM
> Subject: [Heathkit] SB200 HELP Please
>
>
> > I'm fixing up a SB200 amp for a nice old gentleman who belongs to our
> club.
> > I've run into improper plate voltage readings on the meter. The problem
> > appears  to be the plate voltage dropping resistors. They are
> supposed to
> be 4.7 Meg
> > but  test out between 6.2 and 9.8 Megs. I need to replace these three
> > resistors  to finish it for him. I don't want to series up smaller
> resistors and have
> > a  sloppy job. I'd like to keep it original. Does anyone have three 4.7
> Meg
> > one watts resistors? I'll be happy to pay for them. I can't
> purchase them
> > anyplace because it's too small of an order. Regards, Larry   kh6ity
> > Brownsville, TX.
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 27 Mar 2005 08:14:02 -0800 (PST)
> From: Glen Zook <gzook at yahoo.com>
> Subject: Re: [Heathkit] SB200 HELP Please
> To: KH6ITY at aol.com, heathkit at mailman.qth.net
> Message-ID: <20050327161403.96194.qmail at web52908.mail.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Mouser http://www.mouser.com does not have a minimum
> order for the United States, Mexico, or Canada.
>
> Glen, K9STH
>
>
>
> --- KH6ITY at aol.com wrote:
>
> Does anyone have three 4.7 Meg one watts resistors?
> I'll be happy to pay for them. I can't purchase them
> anyplace because it's too small of an order.
>
> Glen, K9STH
>
> Web sites
>
> http://home.comcast.net/~k9sth
> http://home.comcast.net/~zcomco
>
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> ------------------------------
>
> Message: 3
> Date: Sun, 27 Mar 2005 23:48:39 -0600
> From: Robert Nickels <w9ran at oneradio.net>
> Subject: [Heathkit] SB-102 RF voltages
> To: "HEATH at LISTSERV.TEMPE.GOV" <HEATH at LISTSERV.TEMPE.GOV>,
> 	"heathkit at mailman.qth.net" <heathkit at mailman.qth.net>
> Message-ID: <42479AB7.2000204 at oneradio.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> In my continuing quest to get this SB-102 off my bench, I wonder if
> anyone has ever made - or can point me to a reference for - stage gain
> measurements on the SB-102 transmit side?  I've read several articles
> that agree transmit gain is on the low side anyhow, but wide open I just
> can't get more than 75 watts out on 20 meters even after trying all the
> regular tweaks and twiddles.   I can get full output on 10, leading me
> to suspect the 2nd mixer or driver but can't nail anything down.  The
> info in the manual is pretty sparse, but if I had RF voltage
> measurements from a known good working unit, that should help me isolate
> what's wrong.  Thanks for any help.
>
> 73, Bob W9RAN
>
>
>
>
> ------------------------------
>
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> End of Heathkit Digest, Vol 14, Issue 27
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>