Hi Jim, Yes, got to keep busy. I have been collecting parts for a 3-1000Z amplifier. I know life is short and it will end some day without warning so I should do what I can while I can. Thanks for keeping in touch.
Great explanation of isolating the Icom from your other gear for control. The ONLY comment I would make is you might want to put a clamp diode across the relay coil to quench the back EMF when the relay is de-energized so you don't get a big high voltage spike on the radio that is driving the relay coil. IE, the diode anode to the Icom's "output" and the cathode on the +12V from the power supply. Good to see you again! I hope you are doing good. Take care and see you again soon!
I totally agree and finally did that, put the diode across the relay coil. I should know better. I remember long ago I build some kind of 2N2222 transistor relay circuit that had a relay across it and it shorted immediately on the first actuation of the relay. I think I changed the transistor only to have it happen again. Then I kind of figured it out. It would really be ironic to use a larger relay and have a 300+ volt spike destroy the tranceiver when I am trying to save it... 🙂
Thanks for showing this in detail - I was about to build one, then I ran across an Ameritron ARB-704, for a good price. It does the same job with a MOSFET, so there is no delay. My setup doesn't need any more than one switched output, but it would be easy to add more. Cheers,
I have to assume there are some robust ports in these most of the new radios or they would be constantly blasted by experimenters. As mention in the video, vintage equipment may be switching AC, including line voltage or DC up to 150 volts or so. I use these relay boxes on everything to make sure and the delay is a few mS so, I have never had an issue there. Thanks for your comments. 73
As mentioned in a comment below, it would be good-practice to add a diode across the relay coil. The cathode of the diode goes to the plus (+) side of the relay and the anode to the negative (-) side of the relay. What this does is suppress (basically shorts) the collapsing magnetic field that is emitted back into the SEND circuit when the contact in the iCom 7300, or whatever radio you are using, opens. Even a small coil can emit a large spike voltage when the voltage across it is removed. It is good practice to add this snubbing diode to DC relay coils. The diode would not be used directly on an AC relay coil. An AC relay coil would use an RC circuit to suppress the collapsing back-EMF. 73 WA4QGA
Did you consider putting a silicon diode across the relay coil so that when the coil de-energizes the reverse emf is shunted? Otherwise the 7300 could see quite a large voltage spike. 73!
How tubes you amplifier? 833a ? How Ua? ,how power output? И вообще сама коробочка классная, в ней можно было и блок питания разместить и секвенсор сделать
How tubes you amplifier? 833a? How Ua? ,how power output? And in general, the box itself is cool, it was possible to place a power supply and a sequencer in it. I have other videos on the 833A amplifier that may help. th-cam.com/video/ySxk9EOWdJg/w-d-xo.html th-cam.com/video/mbaYUkZlMsw/w-d-xo.html
I built one of these type boxes over a decade ago. It's always a good insurance policy. 👍 Do you have any experience in building one to key multiple amps, either singly or together? I'd like to build one that can do more than one, but aren't sure how to keep the keying circuit electrically isolated between the amps. I don't mean like an optoisolator, but with simple diodes. I'm sure it would be relatively easy, but unsure if there's enough isolation between all the keying circuits...
One of the reasons I wire up all the contacts on the relay is so I can control different amplifiers at the same time. I just have the amplifiers off that I do not want to be initialized. The only device that I can think of at the moment that needs a N/O contact is the Collins R-390. I have one box wired with the 12V present at all times on an RCA jack to power other units. It can get complicated with all the cables running around the room but you can do it.
I never had a SB-220 but I just checked the schematic and see it has 120 VDC on the relay coil to the SEND connection. They do this by utilizing the bias supply and not having to provide another voltage just for the antenna (ANT), (SEND) relay. 120 VDC should blast the new rigs a good one. I know many people use a foot switch for their amplifier but this relay box will make it safe to connect vintage devices to modern equipment. 73 and thanks for your comments.
@@ElPasoTubeAmps Yelp tried both they seem to work had 757 yaesue it took relay out so I just got older rig still have to key I was going to put soft start but my tech pass there's a couple tech s here in Florida but miles away
I’m glad your still keeping busy my friend
Hi Jim,
Yes, got to keep busy. I have been collecting parts for a 3-1000Z amplifier. I know life is short and it will end some day without warning so I should do
what I can while I can. Thanks for keeping in touch.
Great explanation of isolating the Icom from your other gear for control.
The ONLY comment I would make is you might want to put a clamp diode across the relay coil to quench the back EMF when the relay is de-energized so you don't get a big high voltage spike on the radio that is driving the relay coil.
IE, the diode anode to the Icom's "output" and the cathode on the +12V from the power supply.
Good to see you again! I hope you are doing good.
Take care and see you again soon!
I totally agree and finally did that, put the diode across the relay coil. I should know better. I remember long ago I build some kind of 2N2222 transistor relay circuit that had a relay across it and it shorted immediately on the first actuation of the relay. I think I changed the transistor only to have it happen again. Then I kind of figured it out. It would really be ironic to use a larger relay and have a 300+ volt spike destroy the tranceiver when I am trying to save it... 🙂
Thanks for showing this in detail - I was about to build one, then I ran across an Ameritron ARB-704, for a good price. It does the same job with a MOSFET, so there is no delay. My setup doesn't need any more than one switched output, but it would be easy to add more. Cheers,
I have to assume there are some robust ports in these most of the new radios or they would be constantly blasted by experimenters. As mention in the video, vintage equipment may be switching AC, including line voltage or DC up to 150 volts or so. I use these relay boxes on everything to make sure and the delay is a few mS so, I have never had an issue there. Thanks for your comments. 73
Really nice job on the build and the explanation! You saved me a lot of time. I want to add another device to my PTT on my 7300! 73. Ed-W8EDW
As mentioned in a comment below, it would be good-practice to add a diode across the relay coil. The cathode of the diode goes to the plus (+) side of the relay and the anode to the negative (-) side of the relay. What this does is suppress (basically shorts) the collapsing magnetic field that is emitted back into the SEND circuit when the contact in the iCom 7300, or whatever radio you are using, opens. Even a small coil can emit a large spike voltage when the voltage across it is removed. It is good practice to add this snubbing diode to DC relay coils. The diode would not be used directly on an AC relay coil. An AC relay coil would use an RC circuit to suppress the collapsing back-EMF. 73 WA4QGA
Did you consider putting a silicon diode across the relay coil so that when the coil de-energizes the reverse emf is shunted? Otherwise the 7300 could see quite a large voltage spike. 73!
You are right - I forgot it but it will be in there today - Thank You... 73
How tubes you amplifier? 833a ? How Ua? ,how power output? И вообще сама коробочка классная, в ней можно было и блок питания разместить и секвенсор сделать
How tubes you amplifier? 833a? How Ua? ,how power output? And in general, the box itself is cool, it was possible to place a power supply and a sequencer in it.
I have other videos on the 833A amplifier that may help.
th-cam.com/video/ySxk9EOWdJg/w-d-xo.html
th-cam.com/video/mbaYUkZlMsw/w-d-xo.html
I built one of these type boxes over a decade ago. It's always a good insurance policy. 👍
Do you have any experience in building one to key multiple amps, either singly or together? I'd like to build one that can do more than one, but aren't sure how to keep the keying circuit electrically isolated between the amps. I don't mean like an optoisolator, but with simple diodes.
I'm sure it would be relatively easy, but unsure if there's enough isolation between all the keying circuits...
One of the reasons I wire up all the contacts on the relay is so I can control different amplifiers at the same time. I just have the amplifiers off that I do not want to be initialized. The only device that I can think of at the moment that needs a N/O contact is the Collins R-390. I have one box wired with the 12V present at all times on an RCA jack to power other units. It can get complicated with all the cables running around the room but you can do it.
Needs old drake kenwood or yaesue broke couple newer rigs on sb220 had replaced relays in them finally i got foot switch then never any problems
I never had a SB-220 but I just checked the schematic and see it has 120 VDC on the relay coil to the SEND connection. They do this by utilizing the bias supply and not having to provide another voltage just for the antenna (ANT), (SEND) relay. 120 VDC should blast the new rigs a good one. I know many people use a foot switch for their amplifier but this relay box will make it safe to connect vintage devices to modern equipment. 73 and thanks for your comments.
@@ElPasoTubeAmps Yelp tried both they seem to work had 757 yaesue it took relay out so I just got older rig still have to key I was going to put soft start but my tech pass there's a couple tech s here in Florida but miles away
My uncle had something like this