[Amps] SB-220 Transformer Problem

[Richard]

>On Fri, Apr 05, 2002 at 01:58:41PM -0800, Richard wrote:
>> >I concur.  I don't feel bad for ordering the new caps, I just feel bad 
about
>> >the fact that I assumed that they were bad to begin with.  There is also 
the
>> >heat issue with the bleeder resistors that the Harbach part solves.
>> >
>> Ä  How much $ does he get for Caps and equalizer Res.?
>
>He gets $125 for the pack which can be found on his SB220 page:
>http://www.harbachelectronics.com/reference/harpg3cart.htm There is also a
>larger image of the pack: 
>http://www.harbachelectronics.com/pictures/fb-220.jpg
>
>The pack includes the caps, a PCB, 

€  is the PCB for the 8 electrolytics?

>bleeder resistors, and a frame.  Given 
>that I haven't run the amp yet, I can't attest to the performance, but I'm 
sure 
>they work fine.  However, I am very pleased with the fit and finish of the 
whole
>pack as a unit.  He uses Cornell-Dubilier 480v 210uF computer grade caps 
>which he also sells independent of the pack for $75/8.  When looking for
>replacements, the cheapest caps that I was able to find were about $64/8.
>Given the quality of the pack, in my opinion, the price delta of $50 is worth
>it.
>
>> >That was one of the "various things" that I tried which resulted in more
>> >smoke and a tripped breaker.  Did I mention the smoke? 
>> 
>> Ä  Yes. The transformer is history.  
>
>I'm not surprised.
>
€  But, wait: do you own a canoe that needs an anchor?

>> > I'll plan on making a 
>> >call to Mr. Dahl and see about getting a replacement, though I'm not sure
>> >what the circuit should look like with a tapped seconary vs. a tapped
>> >primary.  Making that change might be beyond my expertise.
>> >
>> Ä  I would order a 1200/800 Vrms secondary; dual 120V, 60Hz-only primarys on
>> a core that will fit. Potting is worth the money on a HV transformer.  You
>> should be able to switch secondary taps with the extant SSB-CW switch
>> Provided you don't hot-switch (the LV-HV switch needs to go closest to the
>> mid-point on the FWD, which is what Kenwood did on the TL-922) -   Dahl's 
E-I
>> cores are good.  Grade-5 HypersilÆ cores are a bit better, but they do not
>> fit well in the rectangular space available.  Dahl's transformers typically
>> have low winding R, so a step-start is advisable.  No-load anode potential
>> should be around 3500VDC/2400VDC.  P-out should be c. 300w more than stock 
on
>> SSB.  However, more V =s more VHF gain, so the parasite suppressors need to
>> be improved and glitch protection is not a bad idea.  
>
>Parasitic suppressors have already been installed 

€  Are they the Harbach suppressors with the 4-t suppressor inductors?

>and I'm definitely going to
>adding glitch protection.  As a result of this post, someone has offered 
>me an original unused transformer which would end up costing less than half 
as much
>as a new Dahl unit.  I wonder if it would really be worth it for the extra 
>300W or so to go with the new Dahl transformer.  I welcome opinions.
>
€  300w more than stock is a drop in the bucket,  To make a noticeable 
difference on a sky-wave HF/MF signal, one must a least double one's PEP. 
 I would not buy a killer transformer unless I had no option.

>> good luck, with your Heath, Heath
>
>Heh, I shall need it.
>
>
>Thanks,
>
ur welcome, Heath

-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
www.vcnet.com/measures.  
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