• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

SB-200 Project

RatsoW8

Supporting Member, W9WDX ARC Member - WD8T
Nov 3, 2009
3,100
1,411
273
West Central Michigan
A minor project but still challenging for a freight guy like me.

I picked up this SB-200 for $150 and installed the soft- key module on Sunday to complete the last of the Harbach mods. The amp has the soft-start, new power supply module and soft-key, It also has two strong Cetron 572B tubes making about 750 watts with 65 watts drive. I was considering picking up a pair of the Chinese tubes currently available on eBay, while they still are available, and storing the Cetrons for backup.

I really like this amp even better than the AL-811H I have but 811 tubes are in good supply and still pretty cheap for a matched set of four.

WP_20150719_008_zpsighsdjdk.jpg


WP_20150719_010_zpsufpjsfr3.jpg
 
  • Like
Reactions: binrat

I converted an SB200 to a 6 meter monobander, converted the amp key relay over to 12 VDC so my modern rig doesn't "see" the normal voltage.

works great
 
  • Like
Reactions: TonyV225
God deal on putting the SB200 on 6 meters, are the 572B tubes stable on 6 meters or did you have to add any more circuits to the tubes or more bias???
 
Ratso the SB200 looks good on the mods,
I have two of the SB200 one has all the harbach mods in it ( got it from Exit Thirteen thanks my friend) second one is stock except for changing the RF in connector.

Great old work horse of a desktop amplifier
 
I do like the SB-200 and have had a few over the years. Easy to tune and barely gets warm running it full output on SSB. This is the one they'll have to figure out what to do with when they find me croaked in my shack...lol

I was keying it with one of the Heil double foot switches and it wasn't a big issue. RF in jack is still stock and I made a patch cable for it with one of the nice rca plugs I got with my FTDX-1200. I think I'm going to use it with my TS-140S on a dedicated 17 meter station and the 811H with the 1200. Going to put up a 17m dipole this weekend. Will try an inverted v with the apex at 50 ft. first, broadside facing ne and sw..

I love having space again to play with wire antennas.
 
Thanks for the link. I don't think I've tried in on 17 yet but it looks to be a pretty simple mod. I'm going to put the 17m V up early before it gets hot and monitor 18.125 throughout the day on the TS-140.
 
working today Ratso will be home if I get off work on time around 4pm I will give a call out on 18,125 if it is not in use.
Catch you in forum chat around 4 ish if the weather permits
 
working today Ratso will be home if I get off work on time around 4pm I will give a call out on 18,125 if it is not in use.
Catch you in forum chat around 4 ish if the weather permits

Sorry I was a little tired when I posted last night. I'll be hanging the antenna on saturday. Normal work day for me today.

I'll jump on the chat tomorrow morning after my honey do's are done.
 
sounds good Ratso been nothing but rain here in afternoons, honey do list here in morning early afternoon will be in forum chat when I get back from the thrill of visiting the asian food mart
 
I would hold out for the new RF Parts version of the 572B tube, not the ones on eBay as they may be from a previous bad production run.

Wonder when RF Parts going to release more of their new version of the 572B tubes? The site says they are still on back order. High demand? hmmm.

https://www.rfparts.com/tubes/tubes-572b.html
 
I've been watching the RF Parts page. I think they saw an opening to create their own supply and demand situation and lots of people are holding out for their run of 572B's. They even went as far as to allude that most of the other 572's out there currently for sale are RF Parts and Ameritron returns that didn't meet specs. Makes me wonder.

I'm not using the SB-200 much until I see 572's start to return and I'm not holding my breath for RF parts to have any anytime in the near future.
 
The Chinese plant that was making 572b's ceased production a couple years ago. So the ones you see now are returns or old stock. RF Parts is more worried about quality then quantity, so you have watch their site for availability. I did see some a few weeks back, so there is hope.
Rich
 
Last I heard about the 572B is RF Parts is working with the manufacture in China to improve quality control and reliability of the tube.

Supposed to be available sometime this year.

In one of my SB200 I have the original Centron tubes still putting out full output.

I keep the drive down to around 65 watts and just cruise the amp, great little table top amp.
 

dxChat
Help Users
  • No one is chatting at the moment.
  • dxBot:
    Tucker442 has left the room.
  • @ BJ radionut:
    LIVE 10:00 AM EST :cool:
  • @ Charles Edwards:
    I'm looking for factory settings 1 through 59 for a AT 5555 n2 or AT500 M2 I only wrote down half the values feel like a idiot I need help will be appreciated