Did a lot of research/ talking on this one, so I posit this; Hypersil
cores are pre-formed and "bandsawed" in half prior to assembly, which is
done with band-clamps. In sum the core HAS to be shorted plate to plate,
hence that is highly unlikely the cause of my heating & "ratio loss" issue.
My case is different in that the plates, presumeably new, are losing ratio
as time under power "on" (not load) is steadily decreasing. Whatever is
going on is continuing to get worse ... Bottom line is, though I think they
are out of business anyway, avoid "Heritage" transformers. Whatever was
used, in my case, was junk. $300.00 wasted. 73 Dave N3DB
----- Original Message -----
From: "Gary Schafer" <garyschafer@comcast.net>
To: "'David Craig'" <davidhcraig@verizon.net>; "'Roger'"
<sub1@rogerhalstead.com>; <Gary@doctorgary.net>
Cc: <Amps@contesting.com>
Sent: Thursday, February 12, 2009 12:44 PM
Subject: Re: [Amps] Transformer heating (problem?)
> If you ran a drill thru the bolt holes you probably created a short from
> plate to plate in doing so.
>
> 73
> Gary K4FMX
>
>> -----Original Message-----
>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
>> Behalf Of David Craig
>> Sent: Thursday, February 12, 2009 2:07 AM
>> To: Roger; Gary@doctorgary.net
>> Cc: Amps@contesting.com
>> Subject: Re: [Amps] Transformer heating (problem?)
>>
>> It may well have been Roger- I can't tell for sure. One thing that
>> bothered me a LOT was that when redoing the E I core lamination thru
>> bolts,
>> some of the plates were not aligned properly- I had to grind/drill parts
>> of
>> the holes to get a teflon-insulated bolt thru it (and it was markedly
>> smaller than the actual core hole diameter). This is beginning to appear
>> more & more like a bad transformer design/assembly issue. 73 Dave
>>
>>
>> ----- Original Message -----
>> From: "Roger" <sub1@rogerhalstead.com>
>> To: <Gary@doctorgary.net>
>> Cc: <Amps@contesting.com>
>> Sent: Thursday, February 12, 2009 1:38 AM
>> Subject: Re: [Amps] Transformer heating (problem?)
>>
>>
>> >
>> >
>> > Gary Smith wrote:
>> >> I'm sure no expert, any chance the Iron's not built for 60Hz?
>> >>
>> >> Gary KA1J
>> >>
>> >>
>> > My question would be: has the transformer ever been fully disassembled?
>> > To me the original problem would have indicated this might be a strong
>> > possibility. I'm assuming this is the standard "E" frame with the
>> > laminations interleaved. If so it's possible the laminations may have
>> > been cleaned leaving them to make irregular contact with each other,
>> > causing some current loops, or aggravated historesis (sp?) loss.
>> >
>> > It's been over 40 years since I studied this stuff so I may be wrong.
>> >
>> > 73
>> >
>> > Roger (K8RI)
>> >>> Corollary to a previous issue with a B+ transformer I passed thru
>> >>> the group a while back, which before I repaired it had a current loop
>> >>> due to bad/no insulation on the core bolts. Transformer has a 240V
>> >>> primary, 2800-3000V secondary rated at 2 amp CCS. Is installed & in
>> use
>> >>> on a HB GS35b 6m amp. When "module" testing the amp the transformer
>> >>> taps met specs, measured with a Simpson 260. Calculations based on
>> >>> measurements then indicated a 12.5 to 1 ratio.
>> >>> Fast-forward to completed amp...After some occassional use (~30
>> >>> minutes of total operating time) am having the following "issues."
>> The
>> >>> 3000VAC secondary tap is now only putting out 2700VAC with line
>> voltage
>> >>> measured at 243VAC (240V mains line is 10 guage wire, a 10 ft run
>> from
>> >>> the breaker box & then 6 feet of 12 guage line to the amp...
>> >>> original
>> >>> measurement taken with same lines). The even more disconcerting
>> >>> problem is that after a couple hours of sitting at "idle" (amp on,
>> power
>> >>> to B+ but no RF) the transformer iron is getting hot- enough that you
>> >>> wouldn't want to keep your hand on it for long, and particularly so
>> near
>> >>> the left & right sides of the core. (Yes, I checked the plate meter &
>> no
>> >>> current thru tube, bias relay fine).
>> >>> Lamination bolts remain cold so no more current loop around the
>> >>> mounting brackets.... I am baffled as to why this thing is getting
>> hot
>> >>> just idling. There is no "bleeder" per se on the PS, just 6 x 220k
>> ohm
>> >>> Rs across each of twelve 450V caps in series. The only other
>> >>> constant
>> >>> current draw is a 5 MEG dropping R to the B+ meter. I am baffled as
>> to
>> >>> why the transformer laminations would get hot with almost no current
>> >>> draw, and am concerned that once I really work this thing out during
>> >>> a
>> >>> contest or Es opening the heat is going to short the secondaries.
>> >>> Any ideas as to what could be going on? Is this normal, or as I
>> am
>> >>> beginning to think, an 86 lb misdesigned piece of junk??? Any input
>> >>> appreciated.
>> >>>
>> >>> 73 Dave N3DB
>> >>>
>> >>
>> >> _______________________________________________
>> >> Amps mailing list
>> >> Amps@contesting.com
>> >> http://lists.contesting.com/mailman/listinfo/amps
>> >>
>> >>
>> > _______________________________________________
>> > Amps mailing list
>> > Amps@contesting.com
>> > http://lists.contesting.com/mailman/listinfo/amps
>> >
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|