Heathkit SB-221 Replace Meters - Amplifiers Forum at eHam.net

$\'\'$

$\'\'$

$\'\'$

eHam.net Forum : Amplifiers : Heathkit SB-221 Replace Meters

Forum Help

1-10 of 18 messages

Page 1 of 2 Next

Heathkit SB-221 Replace Meters	Reply
by N0YK on January 31, 2009	Mail this to a friend!
Need some help resolving a meter issue on my SB-221, the plate voltage/grid current meter got zapped by a bad tube. Now in need of a replacement meter and not having much luck on where to find one. I have new tubes in the amp and it does make about 500 watts without fine tuning it with the meters, so all I'm lacking is the working meter. Heard the Heathkit swr meters use the same meter, but then heard from someone else that it wouldn't work. Any recommendations? Thanks, Chad N0YK

RE: Heathkit SB-221 Replace Meters	Reply
by KA5N on January 31, 2009	Mail this to a friend!
Heathkit used the same meter in a number of instruments. It has a movement of 200 uamps and 1400 ohms resistance. This meter is used in the SB200 and several of the Heath SWR/power meters and probably other kits. Use the simple calculations to find if this meter is the correct one for the SB-221 (or the SB-220). Parallel combo of 1400 ohms and 5600 divided by 14.1 megohms times 3500 volts (full scale voltage reading) gives the voltage across the meter divided by 1400 ohms gives .000197 amps (200 uamp). So that meter will work and it is identical except for the face which should be removed and replaced with the existing one. The SWR meters often appear on eBay for around $20 which is not a bad price for a replacement meter. Of course buying sight unseen, you never know what you are getting. I once looked at all the SWR meters to determine which ones used the correct meter but have misplaced that info. The very oldest power meter used a different one but all the ones produced back in the late 60's and 70's were OK. ymmv Allen

RE: Heathkit SB-221 Replace Meters	Reply
by W1QJ on February 1, 2009	Mail this to a friend!
None of the heathkit SWR meters are the same movement as the SB-220/1 meter. It won't work. They need to be reworked if they are going to be used in an amp, just changing the face and putting it in the amp will blow the meter up since the SWR meters are about 50ua and not 200ua like the Sb-220. The Sb-200 meter is the same and that one will work with a scale change. Lou

RE: Heathkit SB-221 Replace Meters	Reply
by KA5N on February 1, 2009	Mail this to a friend!
You can believe whatever you want to and do whatever you want to, but check the meters on the HM102, HM2102,HM2103, HM2104 and HM2141 and I believe you will see that all are 200 uamp and look exactly the same as the meter for the SB-220, SB-221 and SB-200 except for the scale. Allen

RE: Heathkit SB-221 Replace Meters	Reply
by W1QJ on February 1, 2009	Mail this to a friend!
Allan, sorry to disagree, but you are wrong. The Heathkit SWR meters you indicate are about a 50ua movement. The Sb-220 type meter is 200ua, you cannot replace an SWR meter into an amp unless you series/shunt it properly or else it will most likely burn up as the meter will pin and burn the movement out in the amplifier. I have worked on this for 12 years now and I know what I am talking about. I have also taken the SWR meters and have made them work in the Sb-220 by doing the proper series/shunting and I offer the service of rebuilding blown Sb-220/1 meters. I wouldn't like to see Chad buy an SWR meter and put it in the amp just to burn it out per your suggestion. Lou

RE: Heathkit SB-221 Replace Meters	Reply
by W9GB on February 7, 2009	Mail this to a friend!
Hoyt Electrical Instruments was founded in 1904, and has supplied analog meter movements as an OEM supplier to a number of analog meter companies over the last 100 years. http://www.hoytmeter.com/products/products.php?catid=60&subcat1id=165 Hoyt Electrical Instrument Works Inc. 23 Meter St Penacook, NH 03303 Please contact us at 1-800-258-3652 or one of our representatives through the contacts link with your custom meter requirements. You will recognize some of their round and square models from equipment made by Collins, Heathkit, Bird, etc. w9gb

RE: Heathkit SB-221 Replace Meters	Reply
by K6RJP on October 20, 2009	Mail this to a friend!
I have a couple Sb-220's and 221's. Most recent one had an open HV-Grid meter. Tried the Heath SWR meter movement approach and it is definitely not a 200 ua movement !! So I shunted the meter with a resistor until I could find a real replacement. Wound up buying a used Sb-220 plate meter from ebay and then swapped the movement with my dead meter. Worked perfect except the replacement needle pivot point is slightly lower then my original unit but it looks fine and is a direct swap. Most people would not even see it. Whatever you do make sure you put back-to-back diodes across the meter to prevent future problems.

RE: Heathkit SB-221 Replace Meters	Reply
by HFRF on October 20, 2009	Mail this to a friend!
Too bad you did not have this problem a few weeks ago, ebay had a few sets for auction. With patience, virtually anything is found on ebay sooner or later. Those who have older amps and plan to keep them might try buying up some spare parts when available. You can always sell them later. Collins owners buy up every part they can find on ebay. They are hoarders. I sold 3 30L1 meters to the same guy and he didn't even own a 30L1. I ask him why he was buying them and he said Collins people buy anything with Collins name on it. And they do have part when needed.

RE: Heathkit SB-221 Replace Meters	Reply
by W1QJ on October 20, 2009	Mail this to a friend!
Chad I have the meters you want, email me at gudguyham@aol.com I have several plate and multimeters for sale.

RE: Heathkit SB-221 Replace Meters	Reply
by W8JI on October 24, 2009	Mail this to a friend!
You guys are being a little rough on Allen for no reason. Allen is the one who is correct. Many Heath meters, I can't recall specifically which though, are the same movements in other products as the 220 and 200 amplifiers. I recall this from a long gone master parts list I had when doing work for Heath. I also recall this because when doing work on new amps for Heath, they sent me a handful of SWR meters to rescale. They liked to use the same movements in multiple items. 50 uA meters cost more, had higher reject rates, and had "sluggish" responding movements because of the lower torque. It would have been stupid for Heath to have used 50 uA movements in all meters. 200 uA is a good compromise between meter resistance, torque, too much or too little "pointer bounce", and cost. Score 1 for Allen on this.

Page 1 of 2 Next

Next Topic: Mirage BD-35 Schematic
Previous Topic: I like to use TL-922 on 12,17 and 30m,without ATU

Email Subscription
You are not subscribed to this topic.

Check our help page for help using Forum, or send questions, comments, or suggestions to the Forum Manager.

$\'\'$