[GreenKeys] Looking For Bits

[Lee Mushel]

Now, clearly understand that I'm not saying any one should any thing.   I am 
simply thinking out loud.   Going back to the 50's it was always generally 
accepted that you used a nominal 120 volt loop supply and you adjusted your 
series resistor to give 60 ma.   Those loop supplies were as basic as you 
can get so no one seemed to worry about .009 % regulation or some such 
silliness as that.   Then along came the Ham Radio magazine and that 
phenomenon called the transistor which usually was an MJE 340  and I recall 
that terminal unit designs then went as low as 12 VDC for the loop.   They 
seemed to work but I still think there were comments about the voltage 
should be 120.   I guess I concluded for myself that this was ham radio and 
no one was too picky about such things.   I guess I have concluded that as 
long as you have a machine and it is connected to some source, be it locally 
located or remote, and you see copy on the page or tape why not be happy?

Lee   K9WRU
----- Original Message ----- 
From: "Keelan Lightfoot" <keelan at mail.grenander.com>
To: "Green Keys" <greenkeys at mailman.qth.net>
Sent: Saturday, August 27, 2011 9:14 PM
Subject: Re: [GreenKeys] Looking For Bits


> This made me think of a more general question... My current loop supply 
> outputs somewhere around 70 VDC; is there any need to go to 135 VDC when 
> I'm running only local loops? As I understand it, the high voltage was 
> needed to overcome the adverse electrical characteristics of a long loop.
>
> The only anecdotal evidence I can provide is that my M28 and M32 both seem 
> more than happy operating on a 70 volt loop.
>
> - Keelan
>
> On 2011-08-27, at 8:10 PM, Keelan Lightfoot wrote:
>
>> 120V, 10VA-ish. A transformer with a few taps would be handy, as 160VDC 
>> seems a bit high for my liking. A 90V tap would give me somewhere in the 
>> range of 135VDC after rectification, which is more the level I am looking 
>> for.
>>
>> - Keelan
>
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