[Heathkit] SB-200 Help

[Peter Markavage]

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
but 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
> 
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