Heathkit HD1416 Code Practice Oscillator Diagram Request

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Heathkit HD1416 Code Practice Oscillator Diagram Request

Postby ys1rs » Tue Oct 25, 2011 12:34 am

Hi guys.

Can someone kindly provide me with a better scan of the Heathkit HD1416 Code Practice Oscillator circuit? I have one found on the internet but the resolution is so low that you can not see the values of the capacitors and resistors.

I know, in this modern days you could build one using integrated circuits like the 555 timer, (in fact I assembled a small one made by Ramsey many years ago) etc. but I am the old "Retro" type of guy who enjoys the mellow sine wave sound from old circuits rather than the square or sawtooth signal from modern circuits.

Thanks in advance.
This photo is from N4MW's Code Practice Oscillator Museum.
He has got the best collection I've seen IMHO. (Visit his page at www.n4mw.com):

Image

Rob.
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Postby PA1FOX » Tue Oct 25, 2011 2:16 pm

Hi Rob,

I think that

http://www.k7jrl.com/pub/manuals/hk/www ... 416SCH.JPG

should give you a schematic clear enough.

Regards,

Alex - PA1FOX
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Postby ys1rs » Tue Oct 25, 2011 6:08 pm

Yes, it is very crisp clear indeed.
Thank you very much.

I have found and bought all the required parts.
Again thanks.

Rob.
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Postby PA1FOX » Tue Oct 25, 2011 6:40 pm

No problem Rob.

Just a tip how I found it. I searched the model number in Google but in Google Image mode. Apart from quite a few pictures of the device like your photo, there were also a few schematics of which this one was quite clear.

Good luck with the project as well as using it!

73,

Alex - PA1FOX
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Heathkit HD1416 Code Practice Oscillator Diagram

Postby KC9LIF » Tue Nov 01, 2011 10:17 pm

Rob,

What transistors are you using for the Code Oscillator? Will general purpose NPN Transistors work for all three or do you need something special?

Thanks,

73,

Kent KC9LIF
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Postby ys1rs » Tue Nov 01, 2011 10:29 pm

The NTE123AP is the one I am using as a replacement for all three.

Works fine.

Rob.
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Postby G0KZZ » Sat Nov 05, 2011 10:44 am

Hi all

I have one of those code practice oscillators in kit form... I'm torn between building it (so as to use it), and keeping it as it is (seems a shame to spoil a piece of Radio history).

Oh the pain, the pain of it all... 8)


Best 73, Mark.
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Postby ys1rs » Mon Nov 07, 2011 4:57 pm

G0KZZ wrote:Hi all

I have one of those code practice oscillators in kit form... I'm torn between building it (so as to use it), and keeping it as it is (seems a shame to spoil a piece of Radio history).

Oh the pain, the pain of it all... 8)


Best 73, Mark.


Mark... I would love to be in your situation...
...and chose from the following:

Option 1: Keep it there as an investment and sell it in 20 years from now to a collector.
Option 2: make one like mine (which is the same circuit with same components) and keep yours un-assembled
Option 3: keep it un-assembled and take pics of each component and share them with all of us.
Option 4: Assemble it and enjoy it as it was the original purpose of its existence.



Rob.
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Postby G0KZZ » Mon Nov 07, 2011 11:55 pm

Hiya Rob

OK, so now I will make you feel really sick!

I not only have a kit (unbuilt), but I also have an assembled one too 8)

When I first bought the kit I wanted to build it so as to use it for Morse practice. While I was flipping coins to decide whether or not to build it another one (already assembled) came up for grabs.

So I ended up with the best of both worlds :D

Another twist of fate meant that I payed a lot less for the units than they originally sold for... (put that revolver down Rob!) :D


73, Mark.
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Postby ys1rs » Tue Nov 08, 2011 6:15 am

G0KZZ wrote:Hiya Rob

So I ended up with the best of both worlds :D

Another twist of fate meant that I payed a lot less for the units than they originally sold for... (put that revolver down Rob!) :D


73, Mark.


:x My goodness. I would have been green of envy before. Good I was able to build my own. :lol:

At present upgrading mine from square type of signal (multivibrator astable) to full sine wave type.

Yeap. In your case... keep it unassembled and sell it in 20 years. 8)

Rob
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Postby G0KZZ » Thu Nov 17, 2011 10:28 pm

I took a couple of quick snaps of the oscillators.

The first one is the HD-1416A Kit, with box, manual, and all the bits. They even supplied a practice key, so no excuses! :wink:

Image


The second one is a HD-1416 (non 'A' version). The main difference visible when you see them is that the 1416 is a blue/grey colour, whereas the 1416A is more brown in colour (doesn't show up very well in these images).

Image


I still say 10/10 for you totally homebrew one though Rob... Anyone can buy a kit but scratch building takes a whole lot more skill.


Best 73, Mark.
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Postby ys1rs » Fri Nov 18, 2011 1:24 am

I like the A version more. Color preference.

Nice pictures and glad you have a small treasure there in the box.
You know what is really unique on those? is the speaker. The speaker is a 45 ohms one. I have looked for those and couldn't find one.
I am starting to believe those are like hen's teeth.

Rob.
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Postby G0KZZ » Fri Nov 18, 2011 8:05 am

Hiya Rob

You can get 45 Ohm speakers here in the UK from Farnell Electronics. In the USA they can be found on the Newark Electronics web site (Newark is US version of Farnell).

Go to: http://www.newark.com

In the product search box (at the top of the page) type "45OHM speaker" and click the 'find' button.

And there you go!

Although one of them is showing out of stock at the moment the other one shows a stock level of 6, and they are $5.57 each.

The UK site Farnell also shows 6 in stock, but it does say that this is US stock levels so it looks like they are showing their US sister site's stock.

Another US site I found was WALLCO Industrial Electronics:
http://www.wallcoinc.com/Calrad_20_301_3_45_ohm_Speaker_p/wal22-20-301.htm

If you can't get those then you could use some of the old WW2 headphone speakers. Although they can be anything up to 1000 Ohm or so impedance, they work just as well and are easier to find.

Another trick I've used in the past is to use an interstage transformer from an old transistor radio (normally found on radios with push-pull audio amplifiers), these tend to have a high and low impedance connections. Just connect the high impedance side to your practice oscillator output, and the low impedance side to your 8 Ohm or 4 Ohm speaker. The transformer steps the impedance down quite well.

In a real bind I've even used small mains PSU transformers, connecting what would have been the primary (mains) side to the circuit, and the secondary winding (output) to the speaker. Again, very simple but it does work. I've even used that dodge when buiding crystal radios that needed high impedance 'phones, but where I only had low impedance hi-fi ones available.


Best 73, Mark.
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