[TenTec] 9420 PS Problem

[Rick W]

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 at earthlink.net>
>To: Rick W <ve7tk at yahoo.ca>; Discussion of Ten-Tec Equipment <tentec at 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 at karinya.net>
>>> To: Discussion of Ten-Tec Equipment<tentec at contesting.com>
>>> Cc: d.e.warnick at comcast.net; Rick W<ve7tk at 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
>>>
>>>
>>>
>> _______________________________________________
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>> TenTec at contesting.com
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>>
>
>
>