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Author Topic: SB-200 Filter Electrolytics Revisited  (Read 4236 times)

Posts: 73

« on: August 31, 2005, 05:41:18 AM »

I'm back to restoring an SB-200, and I'm looking for replacement electrolytics. I do not want to drill holes to accommodate current capacitor styles.  Has anyone installed new style electrolytics in an SB-200 without drilling holes in the power supply board?  If so - how did you accomplish this?  Also, does anyone have a source for new caps. that would not require any modifications to the supply board?  I've searched the internet - until I've turned blue - and haven't found any.

Thanks and 73,


Posts: 73

« Reply #1 on: August 31, 2005, 05:43:15 AM »

Whoops....wrong forum.  I'll move it.

Posts: 3160

« Reply #2 on: October 15, 2005, 05:39:48 PM »

For electrolytic capacitor replacement, CDE/Mallory (US mfg. in the Carolinas) has an extensive web site.
Mouser is a distributor/Dealer
Harbach also sells CDE for amplfiiers


Panasonic (Snap-in & Screw tops)

To meet you criteria -- match the diameter for your replacement -- most new capacitors are actually SHORTER than the originals you are replacing in your Heathkit.

Why not just changout the entire board - with a Harbach Electronics replacement? Like the PW-202

Posts: 74

« Reply #3 on: November 18, 2005, 08:19:03 PM »

Check out -

They sell complete power supply boards with new caps. They also have softstart and a driver board for the relay. I installed all of the above when I restored my SB-200 (that I built in 1968). The SB-200 is going strong - putting out a solid 600 watts.

Posts: 3160

« Reply #4 on: November 19, 2005, 06:43:03 AM »

Replacement aluminum electrolytics capacitors (CDE or Mallory) are readily available.  CDE has a web site catalog for a wide range of capacitors.  Notice that CDE also prominently posts the Load Life (in hours) of various capacitor models.  
Mouser is a CDE/Mallory distributor - and should be able to get any capacitor you see on the CDE web site.  CDE discontinued direct Internet sales earlier this year.
CDE Aluminum Electrolytic Capacitors

For your SB-200, I recommend that you look at the PW-202 board from Harbach Electronics.
The PW-202 is a complete replacement for the old SB-200 power supply board. It features matched computer grade filter capacitors, modern 1000 volt diode rectifiers and a precision high voltage meter resistor string. Included with the PW-202 is the Harbach soft-start module, which reduces the turn-on inrush current to a mere 6 amperes.
Jeff Weinberg - W8CQ
Harbach Electronics
468 County Road 620, Polk, OH  44866
Telephone & Fax (419) 945-2359

Harbach also has a SoftKey module SK-201, to reduce the SB-200 keying voltage for usage with modern solid state transceivers.  Jeff has the SK-201 installation instructions available here:

While you have the SB-200 on the workbench, take time to read and review photographs from
SB-200 Amplifier Rebuild Notes by Bob Norgard, KL7FM

Bob did have a kit of parts available at one point, but many of the parts mentioned in his notes are readily available from: Mouser; DigiKey; and RF Parts

Posts: 3160

« Reply #5 on: November 19, 2005, 06:43:35 AM »

The original Mallory "FP" capacitors for the SB-200 were 125 uF at 450 V (I think 1-3/8" diameter).
The SB-200 HV PC board holes were specific for "FP" twist lock style cans manufactured by Mallory/CDE in the 1960s -- so any other capacitor will require rework - OR you can "restuff" bad cans (specific web sites on how to do this).

RF Parts (CA) use to carry these Mallory replacements for the SB200, but they are now substituing their part number TVLU1775 Sprague 125uF ±20%  500VDC 1.4" in diameter x 4.0" tall ($19.95 each) - so six (6) new ones will cost you $ 120.00

Antique Electronic Supply (AES) also carries some Mallory "FP" cans for restorers of older equipment.

The Harbach PW-202 upgrade board is $ 105.00.

PA0FRI article on his SB-200 modifcaitons with photos.  He used "Snap-In" units for replacement.

This restorer used Panasonic part number ECO-S2WB271EA (from DigiKey) 270 uF 450V 105 degree C parts.  They are PC (printed circuit) board snap-in caps, so you will have to drill holes in the PC board to use ---  use a pin vise and a sharp drill with the phenolic board.  Photo here:

Also, you should add two diodes (e.g. 1N5404 in parallel, connected cathode to anode) across the meter movement terminals. A replacement meter for the SB-200 is close to unobtainium.

Posts: 3160

« Reply #6 on: November 19, 2005, 06:45:05 AM »

From K9STH ....

You can purchase the 120 mfd @ 450 volt capacitors, part number 140-LS121M2W-2240 that cost $3.14 each ($18.84 plus UPS shipping for all 6) from Mouser.

I have replaced the same type of electrolytic capacitors that are used in the SB-200 that are in the Heath HP-23 series power supplies and the SB-400 / SB-401 transmitters with those $3.14 versions from Mouser and they work just fine.

Frankly, the SB-200 is definitely not a "rare" item and therefore there is no need to try and keep the linear "looking" original.  The new capacitors are going to be a lot smaller in physical size than the originals.  However, the new ones are going to work better than the originals.


Posts: 3160

« Reply #7 on: November 21, 2005, 09:12:40 PM »

From Carl, KM1H -

That would certainly not be my choice of capacitor for a HV doubler supply. First of all the ripple spec is far from good, the load life is low and the temperature rating is only 85C. Now for many hams the mantra is "Cheap Is Best" but this is not the time to count pennies.

However I suggest the 105C Cornell Dublier (CDE) 381LX series which is designed for switching supplies and is a superb cap for amp use. Ive been using that series since they came out for all my amp needs.

The Mouser # is 5985-450V150 @ $6.80 each in small quantities. Then reduce the heat in the PS compartment by replacing the equalizer resistors with 100K 5W MOX. Mouser # 286-100K @ .49 each.

The 330MF version of that cap fits perfectly in the SB-220 plastic blocks and noticably improves the regulation.

The amp you save may be your own.

National Radio 1963-69
Member of NCL-2000 Design Team
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