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Author Topic: Side tone generation.  (Read 2857 times)
N8NSN
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« on: June 22, 2013, 05:45:54 PM »

Setting up old boat anchor stations is one of my latest passions. Recently picked up a few things. A DX 60A, HG10, and HR10 (rebuilding the xmtr from PS to PA, slowly) and having fun with it. Replaced some caps and a bad sensitivity pot in the SX-71 (plays flawlessly, now). Picked up an all original (no mods) Knight T-150A -for sixteen dollars- at Dayton AND IT WORKS, with some slight frequency instability issues (may eventually become diligent in finding resolve to this lil drifter) Have heard ALL the T-150A xmtrs drift, but there are remedies... Have it paired with a Hammarlund HQ-110. It's just FUN to run these old glow boxes... So here comes my question:

I want to find a circuit to build that'll provide side tone. I built a great T/R relay with an old Leach 4PDT  115VAC relay. She switches the antennas, as well as provides switching the SB-1000 into active... Easy enough... The way I've been getting side tone is with a receiver tuned in to my TX freq, with no antenna hooked to it. OK, to the RX goes into standby on the HQ-110 while xmtr active... I use bug keys 90% of the time, and a straight key to foster along new CW ops not able to cruise 25<35 WPM... So, would like to build a circuit to put between the key and xmtr. As you might have guessed, if your familiar with the circuitry in many boat anchors- the voltage in the key jack circuit represenyts a challenge. Tried to modify a practice code oscillator into the key line, but the voltage in the keyline made the oscillator go berzerk. As well the induced voltage drop of having a devise in the key line made the VFO even more unstable. So there it is. Any good ideas that would be inexpensive and not require degrading the original circuitry of either the xmtr or rcvr? Was thinking perhaps a very broadbanded (no freq tuning required) unit that could be set near the xmtr and receive enough "rfi" to generate some sort of tone. Like the old 500 mw cb walkie talkies that received all 23 channels at one time, and transmitted on ch 14... Just looking for a way to eliminate a potential excessive front end overload on the hf rcvr that's been being used, should one ever forget to remove the antenna from it. Thanks in advanced.

Jimmie
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G3RZP
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« Reply #1 on: June 23, 2013, 12:08:46 AM »

Use a relay to key the tx, and another set of contacts on it to key an audio oscillator driving a small speaker. If you want headphones, a third changeover set of contacts to switch the headphones between rx and sidetone osc.
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N8NSN
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« Reply #2 on: June 23, 2013, 04:51:48 AM »

Interesting epiphany this morning... Optocouplers are coming to mind. Isolating that key-line voltage...

A friend of mine, also a ham, suggested an old heathkit hd1410(?) keyer...
The ridiculous price these go for now has me thinking it'd be unwise to pay that price for something that's going to be gutted (most likely).
No need for the iambic features, nor the "relatively useless" clunky, iambic paddles features of a 1410 keyer... Just need the tone (for the bugs or straight keys) isolated from the 28volts(?) riding through the key jack line.

Before going on a seemingly endless google search, sifting through page after page of irrelevant "information" weaved into mountains of cheap, sub-standard junk being peddled (sighs) thought coming here and asking if any one built something like  this could steer my thoughts inthe right direction or even better yet, email a schematic of a "simple & inexpensive" circuit.
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KD8IIC
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« Reply #3 on: June 26, 2013, 05:39:22 AM »

 What did you come up with there Jim? I'd be interested in applying side tone to my trusty Ranger without having to use an outboard keyer to do it with...Thanks for the thread!  73 from lane n8aft. Smiley
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KE3WD
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« Reply #4 on: June 26, 2013, 07:42:33 AM »

I lived thru that era, mostly thru my Elmer's shacks, as I was a mere lad with hornrimmed glasses and briefcase at the time, but here is what I remember: 

Some very few CW ops would parallel the old tube driven Code Oscillator with the key in such fashion that the key operated both the Code Oscillator and the Transmitter and that was their sidetone. 

But it may not have been the preferred. 

Back in the day of the boatanchors, we didn't use Sidetone Oscillators per se, for the most part, we also used actual Receive circuits of our signals for CW monitoring. 

There are rather easy and inexpensive ways to achieve that, also back in the day were magazine articles with construction of these things, some as simple actually as a crystal set type of broadband nearfield monitor driving the cans. 

This actually had its benefits over the synthetically derived sidetone. 

You were always monitoring your own signal in realtime. 

That meant that you not only had a way to hear the characters you were sending and keep an eye on your fist, you also were monitoring the health and condition of your transmitters signal in the real at the same time.  Often an advantage with those old rigs, key chirp and other problems instantly known by the operator rather than relying on another operator to tell you about that during QSO. 

73
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WB6BYU
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« Reply #5 on: June 26, 2013, 12:11:29 PM »

I tried a number of options for my Novice rig.  Finally rigged it up with a keying relay
powered from the AC filament voltage, and it had enough of a hum to it that I could
follow my keying.

Later I was visiting a friend with a Swan 500 who wanted a sidetone:  we dug into the
parts box and wired up a transistor multivibrator circuit connected across the same
key, but using diodes in series with each circuit so one side didn't key the other.  This
actually worked quite well as long as both circuits used the same polarity.  A 100V 1A
silicon diode is fine with most grid-block keying circuits, though 400V might be safer with
cathode keying.

The only problem is if you forget to turn on the transmitter - you still hear the sidetone
and think you are sending.  I got a phone call one day as a Novice from a local ham who
wondered why I couldn't hear his signal.  (As it turns out, his "75 watt crystal controlled
transmitter" was a Swan 400 with a VFO, also used on 11m under the callsign "Tumbleweed".)
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KE3WD
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« Reply #6 on: June 26, 2013, 01:47:49 PM »

I found out back then that the use of my Dow Key relay between xmtr and rcvr could be unwired such that the secondary relay did not throw my rcvr into stby - and thus my rcvr could be used as my CW monitor. 

Addition of a SPST switch on that line made it easy to turn off and on. 


73
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VE1GA
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« Reply #7 on: June 26, 2013, 07:43:20 PM »

In addition to several excellent suggestions already presented I recall having built a number of multivibrator circuits that were triggered by an RF pickup (piece of insulated wire) placed near the tank circuit of the transmitter. Built those in whatever little box was available and used a 9 volt battery for power. Don't ever recall having to replace a battery. This was back in the 1966-68 era. I'm reasonably sure the circuit was published in one or more of the amateur journals of the day ... 73, CQ, HR, QST

I actually preferred and used the method described by KE3WD through my Viking Adventurer, DX-60 and Ranger days. Even though it presents its own set of difficulties, there is nothing better than monitoring your actual transmitter. Those days were over when a Hallicrafters SR-160 arrived on scene and replaced that earlier gear.

The recent acquisition of a Ranger II (an attempt to recover lost youth?) may change things again! I particularly like the excellent suggestion of G3RZP.

73, Leigh



 
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N8NSN
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« Reply #8 on: June 26, 2013, 07:44:44 PM »



There are rather easy and inexpensive ways to achieve that, also back in the day were magazine articles with construction of these things, some as simple actually as a crystal set type of broadband nearfield monitor driving the cans. 

This actually had its benefits over the synthetically derived sidetone. 

You were always monitoring your own signal in realtime. 

That meant that you not only had a way to hear the characters you were sending and keep an eye on your fist, you also were monitoring the health and condition of your transmitters signal in the real at the same time.  Often an advantage with those old rigs, key chirp and other problems instantly known by the operator rather than relying on another operator to tell you about that during QSO. 

73

This is exactly what I want to do. I've used an old HD-1410 keyer with some hybrid rigs and a few transistor rigs; none of which had voltage on the key line... A Heathkit HD-1410 may dislike the keyline voltages just like the oscillator I had in parallel...

And... Hello Lane. Have to catch up on the 7110 some time. Heard you on there Monday, but was elbow deep in a project & couldn't call.
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KD8IIC
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« Reply #9 on: June 27, 2013, 07:48:03 AM »

  FB Jim! Thanks for listenin'...The photo-coupler idea is great. Those are used to interface the functions in my 5 remote controlled locomotives..Yes, 1:1 scale railroading.
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