[Amps] Simple question

[StephenTetorka@cs.com]

Hello David:

Kindly accept my apology for apparently upseting you with my "Simple question" in the Subject window.

I have no reason to dislike you and I stand better informed on such protocols from your helpful reply - thank you.

My wish to keep this particular transformer is for the simple reason that it is circa 1930 which is the vintage of AM tranmitter I am gathering parts to make...( 227's in the speech section + 849 moded tube + 204 final using Hesing modulation.)

I am striving to use as many contemporary components as is practical - and affordable - in my circumstance.

>From another point of view, my nature is such that I would not discard the unit as it would provide me the opportunity to re-wind it...very much as a Ham in 1930 would consider doing too.

Thank you and the other kind folks in this fine group for assisting me in this endeavor.

Warm regards to all,
Steve
WA2TAK





David Kirkby <david.kirkby at onetel.net> wrote:

>StephenTetorka at cs.com wrote:
>> Hi guys:
>> 
>> I have a vintage filament xmfr.
>> 
>> Voltages are a little high without load...and making allowance for 120 in 
>> place of 110 ...and there is evidence of repair and sign of past leaking resin.
>> 
>> What the 'recommended' way to work up a full load - 10 Amps - to see if this 
>> bugger can handle it?
>> 
>> Tnx,
>> Steve
>> WA2TAK
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>> 
>> 
>Can I make a simple suggestion - you pick a more appropriate title. Why 
>not "testing filament transformer" or something like that? Then people 
>will not have to read things they know nothing about. Archives can be 
>searched in a sensible manner etc.
>
>Personally, given its condition I would try to get another and throw it.
>
>(At this point you really don't like me!!)
>
>Now to answer your question.
>
>The best test is going to be to find what the *maximum* heater current 
>will be. That will not be the normal one, but worst case - i.e. look at 
>the data sheet. Then get a resistor and load it up.
>
>R = Volts/current.
>
>Power = voltage * current.
>
>Given the power, which is likely to be 50-100W, it will need cooling. A 
>100W resistor will need a heat sink. But I'm pretty sure a bucket of 
>water would do fine. I have not tested it I must admit, but unless it 
>boils around the resistor, which is most unlikely at that power, I think 
>that would be fine. The resistor would not get too hot.
>
>If you have a decent heat sink to screw it to, then all the better. But 
>for test purposes only, water will do. At that resistance, which will 
>only be an Ohm or so, you need to be careful about lead resistance, so 
>take that into account. Short the DVM leads and subtract whatever you 
>get from the resistance you measure.
>
>Water is a bit conductive, but it will have negligable effect on a 1 Ohm 
>ore so resistor. If it was 100k or more, then perhaps so.
>
>If you have a decent 4-wire meter, then it will be much more accurate, 
>but I doubt you have that.
>
>But personally I would throw the transformer. If it shows sign of repair 
>and leaking resin, I suspect it has been overloaded at some point. You 
>have no idea how much damage it has done. It might work today, but next 
>month it might be another story. If heater current gets removed from a 
>tube, it is unlikely to do it a lot of good if running at full output.
>
>-- 
>David Kirkby,
>G8WRB
>
>Please check out http://www.g8wrb.org/
>of if you live in Essex http://www.southminster-branch-line.org.uk/
>
>
>