[Heathkit] SB-200 Help

[Peter Markavage]

Although the homebrew keying interface should not be an issue with the
847/200 combination, what I would try is to disconnect all the interface
connections you made, and return the SB-200 keying to it's original
design. Once done, to key the SB-200 all you have to do is ground the
keying connection on the back of the SB-200. A simple toggle switch
between the connection and ground would work, or a simple clip lead, one
side to ground on the SB-200 and the other clip lead attached to the
metal of a short narrow screwdriver. Holding the screwdriver by its
insulated handle, insert the end of the screwdriver into the socket until
you hear the relay close. Then apply some RF to the SB-200. For testing,
I would not use any ALC connection between the 847 and SB-200. Actually,
I never use any ALC connection between any rig driving my SB-200's but I
have a monitor scope hung on the output of the SB-200 to monitor by RF
output.

Pete, wa2cwa

On Fri, 10 Aug 2007 02:47:16 -0500 "kb0nly" <kb0nly at mchsi.com> writes:
> It gives me grief on every band except for 40m for some reason, on 40 
> i can 
> run full output of 100w on the 847 and get full power out of the 
> amp.  But 
> when i go to 10, 15, 20, 80, then i get HI SWR on the 847 and i 
> can't drive 
> the amp.
> 
> I tried your suggestion, was just about to say the heck with it and 
> go to 
> bed and leave it for another day.  I put the radio in AM mode on 
> 80m, put a 
> dummy load on the amp and tried adjusting it for max output.  That 
> works ok, 
> but only if i stay under 20w, anything above 20w and the 847 folds 
> back and 
> indicates a HI SWR once again.  I can tune across the entire band as 
> long as 
> i stay under 20w it doesn't present a high swr to the radio, if i go 
> above 
> 20w then the entire band presents a hi swr again.  So i can't find 
> any place 
> on the band where it will take full power!
> 
> I have been trying to find info in the manual and on the web with no 
> 
> success.. How do you adjust the input coils on the SB-200 and what 
> should i 
> look for regarding the flaky meter shunts that you mentioned?
> 
> As for the previous owner, he was using the exact same radio, 
> FT-847, which 
> was a bit of a selling point seeing how well it worked for him.  I 
> hauled it 
> home and got the exact opposite.  The only difference is he was 
> using an 
> external keying interface and i built in the SK-201, well a home 
> brew 
> version of that circuit, to use with my radio.  That works 
> perfectly, just 
> the SWR problem to deal with now.
> 
> 73,
> 
> Scott
> 
> 
> 
> ----- Original Message ----- 
> From: "Peter Markavage" <manualman at juno.com>
> To: <heathkit at mailman.qth.net>
> Sent: Friday, August 10, 2007 2:38 AM
> Subject: Re: [Heathkit] SB-200 Help
> 
> 
> > You didn't indicate what band you were operating on. Try to test 
> it on a
> > band like 20 or 40 meters where the max. is 300 to 350 Khz. It 
> could be
> > the SB-200 input coils for each band were tuned to at a certain 
> point in
> > each band, and it you're not testing anywhere near that point, the 
> 847
> > probably would see a high SWR. One of the problems when running a
> > solid-state rig that is very sensitive to SWR beyond the 
> manufacturer's
> > normal range. You also didn't indicate what mode you were testing 
> in.
> >
> > Try this; put the 847 in the AM mode, key down and then adjust the 
> 847's
> > output to about 10 to 15 watts. Put the SB-200 output on a dummy 
> load.
> > Since the SB-200 is a linear amplifier, don't screw with dip and 
> load.
> > Just tune the amplifier for maximum output either using the RF 
> output
> > meter position or an external meter between the dummy load and 
> the
> > SB-200. If you want, you could take a minimum of a 100 watt light 
> bulb or
> > higher wattage and connect that to the output of the SB-200 
> instead of
> > dummy load. Note: don't try this in the key-down CW position or a
> > modulated SSB position. You'll burn out the bulb. Again, for 
> testing
> > purposes and on a dummy load of some sort, and running the lower 
> 847
> > power on AM, you can sweep (tune) each band with the SB-200 
> connect to
> > see if there's a dial range where the SWR is manageable. Once 
> you've
> > determined, that both rigs can work together on some range of 
> frequencies
> > you can determine what, if any additional action you might 
> want to
> > take. i.e. automatic or manual tuner, if possible, between the 847 
> and
> > SB-200, or readjusting the SB-200 input coils for your range of
> > operation. There's lots of great info on the SB-200 on the web. 
> Also,
> > meter shunts in the SB-200 were known to get flaky after many 
> years of
> > operation.
> >
> > You also didn't mention what type of rig the previous owner used 
> to drive
> > the SB-200. I've driven my SB-200's with an Icom IC-706MKIIG, 
> IC-706,
> > IC-756PRO II, IC-7000, Kenwood T-5999D, Kenwood TS-830S, and tons 
> of
> > boatanchor rigs.
> >
> > Pete, wa2cwa
> >
> > On Thu, 9 Aug 2007 23:48:42 -0500 =?iso-8859-1?Q?KB=D8NLY?=
> > <kb0nly at mchsi.com> writes:
> >> Ok, i got my SB-200 hooked up and now i got more problems than i 
> know
> >> what to do with.
> >>
> >> Lets start from the top..
> >>
> >> I built and installed a SK-201 Soft Key module and that works 
> great,
> >> keys the relay no problem.
> >>
> >> I followed the manual and hooked it all up.
> >>
> >> And i went to the operating instructions, this is where 
> everything
> >> went FUBAR.
> >>
> >> It says to switch it on and put the meter switch on Plate and i
> >> should see 90ma of idling plate current with no drive from the
> >> exciter, i got ZERO.
> >>
> >> Than it says i should advance the drive level of the exciter for
> >> 200ma of plate current.  Can't, why?  Because the amp is 
> presenting
> >> a 3:1 SWR to the radio and the FT-847 backs down the power 
> output
> >> because of the HI SWR condition it's seeing.
> >>
> >> If i flip the meter switch to the Rel Pwr position i can see the
> >> power output of the 847 but thats about it.  I can adjust the 
> tune
> >> and load controls until i'm blue in the face and get nowhere.
> >>
> >> This amp was working perfectly before i bought it, and yes i am 
> sure
> >> of that, but now i can't get it to do diddly.
> >>
> >> 73,
> >>
> >> Scott