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E/R switch in a T-UG8 stand??

Cutlass327

Well-Known Member
May 1, 2016
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NE Ohio
Anyone have any idea on what that is for? I tried searching, but no luck. The only hit I found the answer was the same as if you crossed a rhino and an elephant... :coffee:
 

Dmans

Sr. Member
Jan 22, 2017
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E/R switch=Electronic or Relay switching.
Most tube type radios used relay TX/RX switching. Newer transistorized radios used electronic TX/RX switching almost exclusively.

See page 2 of the pdf. Although a Turner diagram, the same info is applicable to Astatic.

73
David
 

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Handy Andy

Do Your Research First, Then Decide...
Apr 23, 2018
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Well, a long time ago, in an Office Far Far away...

A group of Engineers got together and formed a new foundation for Radios in which the Freedom of bad contacts and poor performance was replaced by...

More bad performance and poor contacts...

Which then they realized it wasn't their fault and so they produced a lengthy tutorial set of Books and introduced us to their lives of Relay Or Not - Here We Come.

E = Electronic, being that the Radio uses SOLID STATE (Read Transistors) to switch RX and TX functions...
R = Relay - being the OLDER style radio that uses a RELAY to handle all the Switching RX and TX functions...

One type, "R" required only two wires and Ground was usually one of them - it simply let the Relay coil switch the RX to TX and Back again once you unkeyed the Mike.

Other type required at LEAST two wires with optional 3rd one for Speaker return (Ground) to let the Radio use a series of Transistors to toggle RX or TX...

The CAUTIONS between the two?

Relay may have wiring Hazardous voltages on the other side of that Switch inside the radio - which may or may not travel back to you....

Transistor - was more sensitive to "static" discharges and due to the nature of the way they were built - oftentimes failed when exposed to high static voltages that could damage the Base of the device and prevent the radio from switching over. That condition was solved later when the Keying circuit was better isolated from excessive static discharges using Buffer Resistor and Divider networks as well as Semiconductor Diodes to offset or shunt spikes so they can sent harmlessly to Ground.

Perhaps...
More than you needed to know, and there is MORE out there...Do you - really need to know?
 

Handy Andy

Do Your Research First, Then Decide...
Apr 23, 2018
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Bingo!
upload_2020-3-31_15-39-0.png
That's the one!

Just so you know, your typical switch used in todays (Read NEWER) models used a DPDT (or Dual Pole Double Throw) you can use 3 contacts. One main (Center or Pole) with the other two Contacts being Normally Open And Normally Closed - so that when you engage the PTT (or the Lazy bar) One Contact opens and the Other contact closes on that same Pole.

The Relay one does that for you - in the older styles. And you only need a wire from the Coil of the Relay to Ground or If the Relay coil was grounded, you POWERED the Relay by taking power from the Radio - into that Relay Switch - thru the Mic Contacts and back into the radio to Turn on the Relay and force it to switch the contacts.

You can also wire up the Switching in the Mic SEPARATELY - because if you have the need for a Separate Relay to Turn on or Off the Transmitter (Read Your Amplifier) - one PAIR of contacts can and were used for handling the Radio - the R side then - switched on or off your Sweet Sixteen and 3/4-qutrs - work with me here...

You really didn't need the slide switch but you could use that extra set of contacts...

It's why I issued the "Caution" before - there used to be a Hi-Pot test to make sure the Relay did NOT send a high voltage spike or otherwise heavy current into and thru the Mic cord - it's an older "Double Insulated" U.L. Standard not too many people recognize these days (nor care).

There were times when people got poked even electrocuted by poor isolation from the Relay design in older Tube Amplifiers and Radio Transmitter equipment.
 
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Handy Andy

Do Your Research First, Then Decide...
Apr 23, 2018
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I had wondered about the large cord - almost twice the diameter of the T-UP9 cords and half the length, too.
Ever wonder why Relays oftentimes used a Diode across the Coil side?

Because of EMF the coil can produce - it's field used to draw in the Solenoid - also generates an EMF kickback. The Diode takes in that and tries to send it to ground so it does not Arc back at the Operator and his switching device - A.K.A - You'd be more A-static than usual...

Shorter wire for a similar reason, voltage drop as well as losses and EMF Hi-Pot pokes...
 
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Dmans

Sr. Member
Jan 22, 2017
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There were times when people got poked even electrocuted by poor isolation from the Relay design in older Tube Amplifiers and Radio Transmitter equipment.

My 4 year old used to like to touch many, many things. I nicknamed him "Fingers" at the time. Mostly it was harmless although sometimes less than desirable.
I was listening to my Browning one day without a mike plugged in and he found the 2 pin plug interesting. As he touched it, he let out a scream I can still hear in my head to this day. He has not forgotten that experience-today he is 30!

73
David
 

Redbeard U812

WDX-1030 / U812 South Texas
Jul 14, 2018
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That explains years ago a funny experience. Friend got a old tube type up and running. He looked like a mad scientist scrounging through draws and boxes.

Ah, ha! He said, and installed the missing tube. Now, we had been drinking, and his wife had gone inside with an attitude because we kept talking louder because she kept turning the radio louder.

He sent her away with a few unmentionables and we went back to setting up the radio. I admit, I'm very green in my knowledge. But he says that we should mix another and let this radio warm up. So we did, finished that round and poured another.

Feeling confident and quite fortified he walked over to key up. BAM! Second he keyed he went to doing a wierd dance, trying to put that lollipop back down. Unfortunately, he had to let go and it hit the floor.

After that, we called that radio HELLCRAFTER.
 

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