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Reviews For: Heathkit SB-200

Category: Amplifiers: RF Power - HF & HF+6M

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Review Summary For : Heathkit SB-200
Reviews: 83MSRP: Original Price $400
Description:
HF Amp using two 572B's, 80 - 10 meters
Product is not in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
14834.9
KU7I Rating: 2003-06-23
great bargain Time Owned: more than 12 months.
Works great 80-10 including WARC bands. Use the 15mtr band for 17 and the 10mtr band for 12. Full output on all bands is around 700 watts. Works just as good on 120 as it does on 240 vac. A real workhorse. If it has the original filter caps in the power supply they may be going bad since the thing was originally sold back in the 60's. This amp is very easy to service. A true bargain. A fair price is $250 to $350 depending on if the supply has new caps, Harbach mods, etc. Buy one, you will not regret it.
K8DGL Rating: 2003-01-18
Nice workhorse Time Owned: more than 12 months.
They made a million of them and I imagine they all worked like mine. Never a problem. Compact table top amp capable of close to 600 watts out. Only complaint is absence of a standby switch.
AA4XR Rating: 2003-01-04
The Orginal Time Owned: more than 12 months.
I'm one, of many, that were around in the 1960's and bought one of these kits for $199.95. It was probably the first "affordable amp" for many hams and has since become an institution. I've owned at least 8 or 9 SB-200's over the years and they've always performed as well as the first one I bought and assembled.
A real STEAL at todays prices and tube replacement is very reasonable. A great starter amp or back-up box that will last for years to come!
N9OH Rating: 2002-12-02
Simple to use - good first amp Time Owned: more than 12 months.
My SB200 was my first HF amp. I probally was a little hard on it -- but it handled my abuse just fine. I occasionaly had some arcing problems but traced it down to a solder joint that had come loose over time. (This amp is easy to work on!) I recently replaced the tubes with a matched pair of Taylor 572b's (from rfparts.com) and can get 500-650w out with 100w drive.

The previous owner of this amp installed a push-button bypass switch on the ptt line so the amp can be ON without being used all of the time. It comes in handy when you want to TX but the amp isn't warmed up yet.

There is an abundance of support availabe for SB200 owners via websites and the AMPS mailing list. Lots of super-smart guys on that list who are more than willing to help you work out the kinks of your SB200.

The only time i would not recommend one of these is if you want to run a full KW or the legal limit. This amp just doesn't pack enough punch for some guys, but its OK for me!

Steve, N9OH
N0TONE Rating: 2002-10-12
Correction to my earlier review Time Owned: more than 12 months.
I looked over my earlier review a bit too late. I was getting the SB-200 and SB-220 mixed up.

There is no low power position on an SB-200, so neglect that comment.

Also, in the SB-200, the grids are not directly grounded. They go through a network of carbon composition resistors. Those resistors have usually drifted high in value, and should normally be replaced. If they've drifted high enough in value, then the amp has been oscillating and you'll have toasted anode parasitic suppressors. Replace them all with more or less stock parts. Nothing exotic required. The carbon comps are hard to find, and I've done just fine with metal film types.

Still a great amp, small and effective.

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Earlier 5-star review posted by N0TONE on 2002-06-06

My rating of "5" is because of the bargain price you can get this amp for. I have purchased functional SB-200s for $50 to $275. The quality of construction varies depending on who built them, since they were kits.

One of my amps is typical of the breed. One of the filter capacitors had been soldered into the board at a crazy angle, and the cardboard wrapper was 1/8" from the chassis wall. The resultant concentration of fields at that spot in the capacitor caused corona, which literally burned a hole in the cardboard. The cap value, too, was way down. I subbed a cap from a parts unit.

Often, you can get them cheap from a CBer (and by doing so, you take an amplifier off the CB bands). They'll be heavily used, and the resistors in the parasitic anode chokes will be burned, if they've seen a lot of 11m AM usage. My "typical" amp is thick with nicotine, which reduces the breakdown voltages on the air variable caps and bandswitch. So, if it smells of cigarette smoke, figure on a two hour cleaning.

I've had several that arc and spark and sputter. I tried the AG6K mods, but if one of these amps regularly arcs and spits, the AG6K mods did not seem to help. I finally dragged one of the worst offenders down to the shop and used a vector impedance meter to check things out. Turns out the very long ground loop caused by having the grid ground on the opposite end of the chassis from the tune cap ground is the culprit. You can't do anything about that, but I did enough measurements to realize that the amplifier's stability was significantly affected by the tuning of the input network. On 40 and 80 meters, I tune the input pi networks to the low end of the band. On 20, 15, 10, I tune them high. This seems to help quite a bit.

On one amp I had with new Svetlana tubes, it was very difficult to tame, and it took out several AG6K suppressor kits. I finally added 10 ohms in series with the cathode, as RF negative feedback, and I got all the stability I needed, and was able to go back to stock suppressors, which run cooler.

The grids on these tubes are very rugged. Some have suggested using grid "protection" resistors as fuses. I found that reduces stability, leading to more frequency spits and arcs. Don't do it. The grids are so rugged that the tubes can survive anode-to-grid arcs occasionally. If the rig hasn't been run for a while, best to run it in the low power position for a while, this seems to reduce the likelihood of arcs when you do finally switch to high power.

The meter switches are always dirty, have some Deox-IT handy.

I replaced the entire keying system with a low-voltage driven vacuum relay for full QSK, to interface with my solid state exciter. I've added 160 meters to one of them, which is not easy. I used vaccum relays to switch in a couple of padding capacitors at the output, and an open-frame relay to switch a new pi-net at the input. Tricky at best, but it did work. If you don't add to the pi-L coils, you end up with an output circuit which is higher Q than optimum. So far, this hasn't caused any problems; I get about 750 watts out on 160, SSB PEP or brief keydown CW before the HV sags. At that power level, in saturation, the 120Hz power supply modulation is about a percent - 40dB down from carrier, inaudible to most people. That's with old PS caps. Despite the high output network Q, I have not experienced excessive coil heating or tuning drift.

So, this is not an amp for the appliance operator, but you can get it so cheaply, it's a bargain.

If it has a good HV transformer, and most of the parts are present, it's worth buying. The $35 Chinese tubes work as well as anything else, and there aren't any other parts inside that are so expensive as to worry about.

W4IMF Rating: 2002-08-28
SB-200 WARC Bands Time Owned: more than 12 months.
I agree with previous reviewers as to quality and value. However, they all seem to feel that the SB-200 won't function on the WARC bands. It works fine on 12 and 17 meters in the 15 meter band-switch position. For the money, you can't beat it. Suggest doing the Harbach Soft-Key and power supply modifications as those caps are getting long in the tooth and modern rigs can't handle the high switching voltage.
KG5FTK Rating: 2002-06-23
Excellent value Time Owned: more than 12 months.
I used this amp for many years for backup ssb and for rtty (reduced output to 300w out). What makes this amp a great value are the cheap tubes and the low price you can buy a used one on ebay. Try to find another amp that puts out 600 watts you can buy for $200 to $300 in good shape and brand new replacement tubes that cost less than $100. Good deal!!! Negatives, the cooling on this amp could be better and 110 volts keying is lethal to new transmitters. This amp is very easy to work on too..
JAMES_BENEDICT_EX_N8FVJ Rating: 2002-06-23
Bargain Workhorse Time Owned: 0 to 3 months.
The SB-200 is a good value. Quality parts are used such as ceramic bandswitches on the PI tank circuit output, tuned input and the multi-meter rotary switch. The tank circuit variable capacitors have extra wide spacing for the voltages applied. The antenna loading variable capacitor is not a 'receiving' type, the spacing is better. The B+ rectifier diode 'stacks' are rated much higher than the operating voltage and the resistor/capacitor shunt across each diode is not needed- a myth! Another myth is using a 'second class' voltage doubler. A full-wave voltage doubler helps cancel harmonics of the 60 hz input and the capacitors are more than able to deal with the ripple current- nothing 'second class' here. The only item that may need attention is the older B+ capacitor bank. I would replace the caps after the 20 to 30 years use. The amplifier also offers tuned input for a good match with solid-state transceivers. The antenna switching relay is 120 VDC, thus an interface relay is needed for modern transceivers. For $250 to $350 depending upon condition and tube quality, this amplifier is a best value. 70 to 100 watts input will produce 600 to 700 watts output, slightly less on 10 meters.
VK3KCG Rating: 2001-10-11
Good Amp Time Owned: 0 to 3 months.
Picked up this amp in the original box with 2 new cetron tubes as well.This amp is in mint condition and after burning the tubes in puts out around 800 watts on 20 meters.
A couple of small mods I did was to balance the cooling fan and to round the leading edges of the fan, this makes it very quiet, also changed the caps on the grid bypass to 390pf 500 volt Metal clad mica types.
Also added .2 ohms of r in the heater lines to run the filaments at 5.75 volts, this makes no difference in power output and the tubes will last heaps longer.
Also did low Q mods to the anode chokes using nichrome wire.
The line voltage in Australia is 240 but more like 256 at my location.( Thanks power company)

Very impressed as it is easy to tune and operate
WB7QXU Rating: 2001-07-27
A Real WorkHorse Time Owned: more than 12 months.
This is my first Amp. I bought mine many years ago. I was part of a Radio Club which had many amps, I decided on the SB200 because it is a True workhorse, and puts out a Good 600-700 depending on band. 500w 10m I replaced my Tubes with Svetlana and they gave me a extra 50w. it will work 80-10 includ WARC. a little less out on 12 &17 WARC bands but that is ok, I recommend the Modifications. I am going to modify mine soon. I use a seperate relay to key the amp since it is 120v to ground for keying the relay. No good for solid state amps. i have a seperate relay to key the amp. the relay interfaces between the amp and Icom. This is a Great amp it is a keeper and parts are still avail. A little hard but out there.