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[WA2JJH]

I have not had an HF amp in 20 Years. I built the SB-230 conduction cooled single 8873 heathkit. Stupidly
sold it.

  I am about the recieve a Heath kit SB-2200. Ebay deal
Came to $550 shipping included. I guess I overpaid.
I will have to do a 10M mod.
I keep hearing about HARBACH MODS for the older SB-220/1. I am assuming they beef up the pwer supply.
There is little or no info on the SB-2200. It was heaths last amp before they went under.

  If anybody has any experience with modifying the HL-22200, I am all ears! What do the Harback mods really give you. Is the HL-2200 just the SB-220/1 in a different case. Does the HL-2200 use 110V relay switching like the SB-220/1.

 Since there is so little info on the HL-2200, can I do the mods for a SB-221.

  Yes, I bought a "pig in a poke". The O.M. seller seemed decent. Has excellent feedback.

  Some Good O,M.'s told me the tube config. dual 3-500Z
I have concerns with switching. I have a TS-850 and a FT-100D. I guess I can build a RF sensing relay switch.
I have also received conflicting ifomation that the ALC line is not needed. My house wiring casn not handle 2KW. I will be running 1KW tops. So I guess 30 watts of drive from my rigs, should have no need for ALC. I do not intend to pump in any power over 50 watts.

  Good thing I am getting the Manuel. I hope I will not have to do too many mods to bring this 1984 vintage amp up to todays standards.

  Any suggestions or mods would be nice
73 MIKE

[KO4NR]

The HL-2200 is more or less an SB-220 in a different box.

Look at this web site:
http://www.vcnet.com/measures/

and www.harbachelectronics.com

The Harbach mods should work as the HL-2200 is basically an SB-220 anyway.

Keying is a snap with the "soft key" circuit you can get from Harbach Electronics.
73,
Bill

[N0TONE]

1)  HL-2200 is identical to SB-221 except that it has a prettier cabinet, and an added standby switch.

2)  If the amp is un-modified, has good tubes and in good shape, you paid an OK price.  Actually it was a good price.  The ugly green of the SB-220/221 doesn't fit with any shack, and the HL-2200 is far easier on the eyes.

3)  Do NOT build an RF sensing circuit for this amp!!!  If you do, you'll hot switch and toast the T/R relay.  The switching timing of an amplifier at this power level is important.  If the sequence of events is "detect RF from exciter, then activate T/R relay", you guarantee to hot-switch that relay - you switch the relay while RF is applied.  The sequence should be "Detect amp keying signal from rig, and get the T/R relay switched before the rig actually delivers RF to the amp".  There are many circuits that will interface between your solid state rig and the 120V or so that the amp keying uses.

4)  Don't go overboard on the Harbach mods.  Many of them are little more than window dressing.  Parasitic suppressor "upgrades" can just as easily send the amp into oscillation as prevent it.  The portion of AG6K's message about modifying the input circuits with more resistance is what tames parasitics, if they even exist.

5)  Don't replace HV filter caps unless the HV is sagging badly.  Just because they're lower in capacitance than when new doesn't mean the amp hums - unless you run it at saturation, which I hope you don't do.

6)  If Harbach offers a kit to protect against arcs, that's good.  Tubes DO arc, in an unpredictable manner, no matter what you do.  Some tube may go 20 years without one, and other tubes do it every few months.  With an arc protection device (a resistor in series with HV supply to limit arc current), you won't blow the power supply or tube grid when the arc happens.

7)  Why don't you want to connect the ALC?  It's just one cable.  Do it.  If something goes amiss with the HV supply or your antenna suddenly goes open circuit, the ALC will cut your exciter back to 100 MILLIWATTS if that's what it takes to protect the grids.  Also, if you are an SSB operator, you can't measure your power accurately enough to know if you're delivering 50W or 100W to the amp - even peak reading meters, ham grade, aren't very good.

 Use the amp for a while before you add 10 meters.  I never find a need for amps on 10 - if the band's open, it's open for QRP.

9)  The only two mods to bring the amp to "today's standards" are the arc protect and low voltage keying, called "soft key" by Harbach.

Good luck and enjoy.

AM

[K0BX]

The hot-switching problem with the older amplifiers can be a problem.

I tried using my TS-850S/AT with a Drake L4B and Drake L7 using the relay inside the TS-850S but both
had the hot-switching problem.

I found a very nice keying circuit for the older amps.  It can be found on my website:

http://www.qsl.net/k0bx  and look for amp keying.  It using the 12 volts on XMT and not the relay.
Since I started using this keying circuit, I have not had any more 'Hot Keying' problems.

It will work with any rig that has 12 volts on xmit.

Joe K0BX