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Old 8th May 2008, 07:40 AM   #1
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Location: Michigan
Default FS: Power xfmrs

I posted in the wrong forum before - apologies for double posting. I'd delete the other if I could figure out how.

Item #2
Bando Japan , late 80's, NOS potted, shielded toroidal power xfmrs made for Harman-Kardon for a 100 WPC power amp that Heathkit arranged a kit of , the AA-2500.

I located several companies named Bando in Japan through a trade agency in Chicago and wrote to the late Nobu Shishido. He was kind enough to contact the companies and verify which was the xfmr mfr and got me data.

Oddly, there is a Bando Malaysia that makes power xfmrs for audio companies since about 1991, different font in their name.

Anyway,
http://www.uptowngallery.org/Murray/Bando/top.jpg
http://www.uptowngallery.org/Murray/Bando/bottom.jpg
http://www.uptowngallery.org/Murray/Bando/side.jpg

5" diameter, 3.9" high, 9#-2 oz net wt. each.

120 primary only
dual c.t. secondary. Heath schematic shows 55-0-55 VDC no load, Bando data says +/-46.5 VDC @ 1.6 A each secondary with 4x10000 uF.

Bottom is steel, 1/4-20 threaded mounting holes. There is a steel band around it inside. I assume the top is shielded also. Potted in some kind of cream-colored hard material, epoxy or other.

Flying leads.

I have contemplated the following off-label uses. use TWO outboard , one for each channel for the Heath/(Leach?) AA-1800 that is so hard to source.

Put all secondaries in series for 6C33C-B at about 200 VDC, 1.6 A separate xfmrs for filament and bias.

Secondaries in series with doubler?
------------------------------
$25 each plus shipping. They are in original unopened Heathkit boxes. I would prefer to open/inspect each before shipping to make sure they all look like new like the one I photographed. I can reach 4 of them right now. There are more.


------------------
Item #1, listed in wrong forum
Heathkit 54-950, made by the former Midwest Transformer in Illinois (EIA code 549). I don't know who absorbed them.

Standard Heath dual primary 120-240, 50/60 Hz
Secondary #1: Center-tapped HV, odd specs - HW Rectifier, 405 VDC no load, 285 VDC @ 80 mADC across the whole winding. half-winding is spec'ed with a load on the 2nd secondary.

Secondary #2: 14.5 VAC 1A

Really rough microfiche blueprint, part 1:
http://www.uptowngallery.org/Murray...0/54-950_1.html
part 2:
http://www.uptowngallery.org/Murray...0/54-950_2.html

pic#1: http://www.uptowngallery.org/Murray/54-950/54-950_1.jpg
pic#2: http://www.uptowngallery.org/Murray/54-950/54-950_2.jpg

2# net weight each. You can see the dimensions in the dwg, or ask me.

$6 each? plus shipping. I should follow up with how many will fit in a flat rate Priority Mail box.
-------------------------------------
Here is a claim I cannot prove: I spoke to an engineer at V&F Transformer, also in Illinois, another Heath supplier, (EIA code 60) way back when, and had a conversation about HW vs FWB rectification. He claimed that due to the DC flux on the core w/ HWR, a transformer is derated with a HWR, and I could nearly double the current with a FWB. It's tempting to believe this, but I can't substantiate it. I don't have loads handy to test this, but might try light bulbs.

I have a lot of these, but have to look. I know where one carton of them are.

They are unused, new old stock from the late 80's.

Some have light surface rust due to unheated warehouse storage, Guaranteed no immersion! Guaranteed functional. I have no idea how quiet they are, but note 2 requires varnish or 'Permafil' to prevent buzz. Permafil was apparently a black epoxy-like stuff.
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Old 9th May 2008, 03:14 AM   #2
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to clarify on the toroids;

That's two sets of secondaries that produce 55-0-55, not one.
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Old 9th May 2008, 07:16 AM   #3
Bob Lee is offline Bob Lee  United States
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I am interest in few of the $6 transformer. Please contact me at
bobjklee at yahoo dot com
thanks
bob
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Old 10th May 2008, 02:25 AM   #4
pchw is online now pchw  United States
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How many can be stuffed into the flat rate priority box? I am interested in buying a flat rate box full of $6 PT's.
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Old 10th May 2008, 09:05 AM   #5
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Hi:

I didn't realize I'd get so many responses. I will try to get things lined up this weekend but work Friday night, Saturday Night and have Mother's Day obligations.

I am not sure how clearly I described the toroids. The 2x 55-0-55 was my late night intention to say two sets of bipolar +55/-55 VDC supplies.

I did not mean 55-0-55 ac. Sorry if any confusion.

Bob G here apparently got some of the 54-950 from me at an earlier date, says they are quiet but seem to run pretty warm. He gets about 390 VDC w/FWB at 20 mA. The warm part doesn't surprise me too much, although it's relative. Heath xfmrs typ. have 40-65 C rise about ambient per data sheet (when available, but not usually a public document :O) at test circuit load.

Thanks
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Old 14th May 2008, 08:04 PM   #6
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Have you determined how many will fit in a flat rate box? I'll take as many as will fit.
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Old 15th May 2008, 03:53 AM   #7
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I'm I-N-C-H-I-N-G closer. Sorry for delay...some personal matters have arisen.

No money will be accepted until items are packed & ready to take to shipper, anyway (you can see my eBay feedback (feedback is OK there ;O) under the same name multi-volti).

Hopefully Thursday I will pack some boxes & report. I am going to wire the small ones to a double walled corrugated sheet so they cannot move by inertia/momentum, and pad as well. I have 29 pieces located of the smaller item 54-950. I know there are more...but don't really know where yet. It's more serial access than random...I have to get past some things to get to others.


I will also measure the output voltages on the toroid at 117 VAC input to be sure that all wires are ID'ed and there is no potential for confusion.

I don't know if I can pull together rectifiers and filter caps in the space I'm in at the moment, but the DC isn't the question. I want to be unambiguous about the ac winding voltages.

Murray
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Old 16th May 2008, 03:50 PM   #8
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What a week.

OK, I am working on the little ones today.

The toroids are too tall for USPS Flat Rate boxes.

I packed one pair @ 21 # (packing materials may vary, depending on what size boxes I have).

A pair of each type came to 24#. West coast from Michigan, Parcel Post and Fed Ex Ground were about even (PP was just under $2 less, but insurance would make them even) $26.78+ins USPS PP, $28.61 Fed Ex Ground. Priority was worse, $41.25.

Murray
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Old 17th May 2008, 06:23 AM   #9
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OK, the 54-950 hv transformer:

5 fit in the $9.80 Flat Rate Priority Mail box.

9 fit into the $12.95 Large Flat Rate Priority Mail box.

Murray
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Old 17th May 2008, 08:26 PM   #10
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I seem to not be able to access data: I'll re-post

http://www.uptowngallery.org/Murray/.../54-950_1.html

Standard Heath double primary: to wire for 120 V primary, connect Black(wire #1) and Black/Green (wire #3) together.

Then connect Black/Yellow (wire #2) and Black/Red (wire #4) together. These pairs form the two 120 connections.
-----------------------
http://www.uptowngallery.org/Murray/.../54-950_2.html

Secondary 2 (14.5 vac) is White-White

Secondary 1 (hv) is Yellow - Red. CT is Red/Yellow
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