Looking at my calculations (assuming 0.7 V drop on each diode):
(12.6 VAC * 1.414) - (2 * 0.7) = 16.4 VDC at the regulator.
When you add in any capacitor ripple I think this is pretty close to the
margin. I think you are right Carl. I need closer to 18 VDC at the regulator.
A 16 VAC transformer would give me 21.2 VDC and that is well within the specs
of the 7815.
I have found a dual primary (115/230 VAC) transformer with 8/16 VAC out at
5.4/2.7 amps (parallel/series ratings). The physical size is close to the
original (Digi-Key P.N. 237-1261-ND). Cost is $11.14 CAN plus shipping and
taxes.
73,
Rick
VE7TK
Website: http://www.ve7tk.com
>________________________________
> From: Carl Moreschi <n4py3@earthlink.net>
>To: Rick W <ve7tk@yahoo.ca>; Discussion of Ten-Tec Equipment
><tentec@contesting.com>
>Sent: Sunday, June 9, 2013 8:57:58 AM
>Subject: Re: [TenTec] 9420 PS Problem
>
>
>It's most likely at least 18 vac output on the transformer.
>
>Carl Moreschi N4PY
>121 Little Bell Dr.
>Hays, NC 28635
>www.n4py.com
>
>On 6/9/2013 11:10 AM, Rick W wrote:
>> Steve and Dave thanks for getting back on this.
>>
>> I was wondering if either of you knew the transformer output
>> specifications. I'm guessing it is around 12.6 VAC at perhaps 1 amp or so.
>> (The regulator is a 1-amp 7815.)
>>
>> It is an interesting design with the transformer on 24/7 while AC power is
>> applied. I shut off AC to all my supplies with a Master switch in the
>> station at the end of each day.
>>
>> Interesting that the T-T replacement is not an exact match. Digi-Key has
>> several in stock and their delivery time to my QTH is amazing. Just want to
>> be close to the original in voltage and current rating.
>>
>> Thanks for the surge suppressor tip bob. I'll look into it.
>>
>> 73,
>> Rick
>> VE7TK
>>
>> Website: http://www.ve7tk.com
>>
>>
>>
>>> ________________________________
>>> From: Steve Hunt<steve@karinya.net>
>>> To: Discussion of Ten-Tec Equipment<tentec@contesting.com>
>>> Cc: d.e.warnick@comcast.net; Rick W<ve7tk@yahoo.ca>
>>> Sent: Sunday, June 9, 2013 7:35:20 AM
>>> Subject: Re: [TenTec] 9420 PS Problem
>>>
>>>
>>>
>>> Mine failed 9 years ago and I fitted a £15 replacement from RS-Components
>>> here in UK. Not much help to you as the part is no longer available :(
>>>
>>> It's worth noting that transformer is powered 24x7x365 if you leave
>> the 9420 plugged in to a powered wall socket.
>>>
>>> Good luck in your search.
>>>
>>> Steve G3TXQ
>>>
>>>
>>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
>
>
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