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T/R Switch function Identification Please




 
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Author Topic: T/R Switch function Identification Please  (Read 285 times)
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KC3GMQ
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« on: August 13, 2017, 11:26:46 AM »

So I have a Hammarlund HQ-180, and when I got it the gentleman included the T/R Switch.  He said he had built it but was to old to remember what he did with the drawing or how it worked.  So I am posting it here to see if anyone wants to take on this task.  I am just not savvy enough yet to figure it out..  I can tell you if it is plugged into the transmitter 117vac mute power, it functions as a T/R switch.  What the switches and red light do,  I have no clue.  I did plug it in and the switches operate the relays, but I am still at a loss.  Thanks if you care to take this on.  Following posts are a bunch of pictures , hope they help
Dave
KC3GMQ


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* IMG_3252.JPG (912.06 KB, 2016x1512 - viewed 39 times.)

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KC3GMQ
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« Reply #1 on: August 13, 2017, 11:27:38 AM »

pictures


* IMG_3253.JPG (994.34 KB, 2016x1512 - viewed 50 times.)

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KC3GMQ
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« Reply #2 on: August 13, 2017, 11:28:09 AM »

pictures


* IMG_3256.JPG (909.09 KB, 2016x1512 - viewed 17 times.)

* IMG_3257.JPG (837.57 KB, 2016x1512 - viewed 12 times.)

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KC3GMQ
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« Reply #3 on: August 13, 2017, 11:28:40 AM »

pictures


* IMG_3259.JPG (753.86 KB, 2016x1512 - viewed 11 times.)

* IMG_3260.JPG (755.58 KB, 2016x1512 - viewed 9 times.)

* IMG_3261.JPG (729.77 KB, 2016x1512 - viewed 11 times.)
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KC3GMQ
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« Reply #4 on: August 13, 2017, 11:29:32 AM »

pictures


* IMG_3262.JPG (849.49 KB, 2016x1512 - viewed 8 times.)

* IMG_3263.JPG (882.48 KB, 2016x1512 - viewed 4 times.)

* IMG_3264.JPG (937.54 KB, 2016x1512 - viewed 10 times.)
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KC3GMQ
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« Reply #5 on: August 13, 2017, 11:29:59 AM »

pictures


* IMG_3265.JPG (910.33 KB, 2016x1512 - viewed 13 times.)

* IMG_3266.JPG (1031.2 KB, 2016x1512 - viewed 15 times.)
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KA2DZT
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« Reply #6 on: August 13, 2017, 08:56:53 PM »

Well, I looked at all the pictures.  you have a box with a lot of nice parts.

Power supply is probably the DC voltage to operate the relays.  Seems he bridged the terminals on one relay, most likely the one to connect the xmtr to the antenna.  Other relay most likely connects the receiver to antenna on receive and probably shorts the receiver line on xmit.  The other lone relay probably mutes the receiver.  So it would be closed on receive and open on xmit.

You'll have to study the wiring and back engineer the unit.  Otherwise strip it down and start over.

Fred
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KC3GMQ
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« Reply #7 on: August 13, 2017, 08:59:41 PM »

Thanks Fred,  It works fine without even plugging it into the wall outlet, so I was curious what all the other function is.  Ill work on it, thank you for the reply.

KC3GMQ
Dave
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Patrick J. / KD5OEI
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« Reply #8 on: August 13, 2017, 10:33:16 PM »

To me it is always an uplifting pleasure on a Saturday or Sunday afternoon to sit down at the workbench with a pipe and some pleasant music and trace out the schematic from something onto paper.
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MikeKE0ZUinkcmo
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« Reply #9 on: August 15, 2017, 07:13:22 AM »

Quote
... and trace out the schematic from something onto paper.
Agreed!
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W2PFY
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« Reply #10 on: August 15, 2017, 11:30:41 AM »

I would suggest you take out your ohm meter and start by taking measurements from the center contact of each SO 239 while flipping switches to see what switch does what from the
input SO-239 to the outputs of the others? If you don't have a meter a 1.5 volt battery and a bulb could accomplish the same result. The terminal strip is probably there to put a CW contact on a transmitter to ground or simply shorts the CW contact on the transmitter to ground therefore keying the transmitter to drive an amplifier etc. If you're going to use it on a regular basis, I would replace that electrolytic.

You may also want to test from the center pins of each SO 239 to ground to see if any are grounding out with a given switch position. Sometimes the connector to the receiver is grounded out when transmitting to avoid burning out the front end of a receiver because of too much RF on the connector.

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