[R-390] ER article for R390A SS regulator

[Cecil Acuff]

Kielbasa works great as a regulator...the natural oils allow the sine waves to slide around easily to keep the current flow consistent.  Allow the oscillators to operate friction free too so stability is greatly improved.  Any excess can be used on the gear train to allow that easy one finger tuning feel we all love.

In south Louisiana they substitute Boudin.  Why you think Nolan was always killing deer in the parking lot those many years back...he used Boudin being a self respecting southern Louisianan.

Cecil
K5DL

Purveyor of dead horses and such..

Sent using lubricated electrons.

> On Apr 11, 2016, at 10:09 AM, Barry <n4buq at knology.net> wrote:
> 
> I have two basic questions regarding 3TF7s and the R390.
> 
> 1. If I understand the ballast operation correctly, when the voltage changes, the current through the circuit changes.  The ballast reacts to that change and the voltage drop across it changes to bring the current back to 300 mA.  Is that correct?  If so, how quickly does the ballast react to get the current back to its specified value?
> 
> 2 (and this one might get me kicked off the list).  Are there solid-state (FET, etc.) replacements for the oscillator tubes that would eliminate the need to regulate any filament voltages?
> 
> Thanks,
> Barry - N4BUQ
> 
> ----- Original Message -----
>> From: "Tisha Hayes" <tisha.hayes at gmail.com>
>> To: "R390A" <r-390 at mailman.qth.net>
>> Sent: Monday, April 11, 2016 9:56:18 AM
>> Subject: Re: [R-390] ER article for R390A SS regulator
>> 
>> When the radio was used in RTTY service while being powered from fairly
>> unstable electric generators it could get drifty enough that the op would
>> need to be constantly tweaking the frequency on a bank of receivers as line
>> voltages went up and down. It made perfect sense to stabilize heater
>> current the BFO and PTO tubes through the use of a ballast tube in series
>> with the tube filaments.
>> 
>> It may be that most radios that are out there today are not going to be
>> operating from a small generator in RTTY service. For those applications
>> maybe it is just fine to use a dropping resistor or another tube filament
>> in series to just keep the bulbs lit.
>> 
>> The 3FT7 is not a perfect solution; as has been said, it is a fairly
>> fragile tube that is getting pretty rare and expensive and there are
>> alternative approaches we can take to further reduce the heat and
>> electrical load inside of the radio.
>> 
>> Any linear device; like a resistor or an LM series regulator is going to
>> need to contend with heat dissipation as the voltage drop is going to be
>> translated in to thermal energy. The difference in voltage between both
>> sides of the device is the voltage drop, times the current (good 'ol ohms
>> law) equals electrical watts that is the same as thermal watts.
>> 
>> If you use a very tiny switching converter as the "sigmapert" device made
>> by Dr. Kurt Schmid the total current goes down because of the conversion in
>> the supply. The heat dissipation drops down to around 1 watt as the
>> converter efficiency is 94%. It is not a magical device, it contains a
>> small commercially made switching regulator with a few other peripheral
>> components for AC to DC rectification and some caps. It does require an
>> additional connection to chassis ground; either by attaching a ground lead
>> to what looks like an anode at the top of the metallic tube shaped device
>> or by running a ground wire to pin #1 of the tube socket. Pin #1 is not
>> used by the 3FT7 tube so if you later decide to pull the solid state
>> converter and put in an old 3FT7 it does not cause a problem.
>> 
>> I have one in my primary R-390A and it has been there for a few years now.
>> It does not run warm and has been reliable. If I feel any guilt I can
>> always pop in a 3FT7 as I have a few spares that I am saving as investment
>> properties to resell to 'yall when the prices climb to $200 each.
>> 
>> *Ms. Tisha Hayes, AA4HA*
>> *"*There are many who live in the mountains and behave as if they were in
>> **the
>> town; they are wasting their time.*
>> * It is possible to be a solitary in one's mind while living in a crowd;
>> and it is possible for those who are **solitary to live in the crowd of
>> their own thoughts.*"*
>> **-Amma Syncletica of Alexandria**
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