Tunnel diode source

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Re: Tunnel diode source

Post by Admin on Thu Feb 23, 2017 11:29 pm

Hi Ivan,
I believe I know the cause of the spurious signals. The whole lash-up was a large birdsnest, just to test the diode. If I shorted the coil then they remained - so the excessive inductances of the wiring were forced in to oscillation. The original coil had little effect since it was a relatively high impedance and my diode driver circuit simply shorted it out.

But by reducing the wires and matching the diode's impedance to the coil it all worked beautifully. I have a lovely clean signal, despite the fact they are switching devices.

I used a voltage divider from a 1.4V cell. Now I have the digital voltmeter I see the voltage is about 160mV and the diode current is about 6mA.

the AEY11 I used in the 60s had a much higher impedance and was not capable of more than a few uW. But this device is dissipating around 1mW, although I suspect that the measurement instrument could be affecting the diode.

> ... have little time to test them. I hope it will turn better soon.       
I know exactly how you feel. I feel that my life has been dictated over the past few years an in November I decided that it going to stop. There are so many things I want to do but I always seemed to have my private life full with "haftas". All my tst equipment had to go, analyser, generators, the lot!

Anyway, I am really grateful to you for the advice you gave me, and I shall take care now that I know they are switching diodes. I think I smell a few new projects coming on. I just need to finish the GDO with all the coils, then the light-box, then a decent bench PSU.

Thank you once more for your help. I seem to be learning and re-learning a lot these days. Hope you have a nice weekend.

Very best regards from Harry - SM0VPO

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Re: Tunnel diode source

Post by Ivan on Thu Feb 23, 2017 7:21 am

Hi Harry,
the spurii may be caused by the fact that these diodes are switching, not amplifier type. I found and ordered some amplifier ones (3I101A), too. They are more rare and more expensive, of course. I am angry I have little time to test them. I hope it will turn better soon.
GaAs has bigger speed of carriers than germanium and silicon, so these TDs may work up to microwaves.

I am glad I could help you a bit.
VBR from Ivan

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Re: Tunnel diode source

Post by Admin on Wed Feb 22, 2017 5:52 pm

Ivan wrote:Hi Harry,
the polarity according to the datasheet is:




Be careful not to exceed the maximum current during experiments.

BR from Ivan

Hi Ivan,
I have received the diodes and just done a few experiments.
Unlike the diodes I used to get in the late 60's, these seem to draw a bit of current. I gradually increased the current until it hit 130mV
As soon as I got the voltage to 0.13V it "sort-of" started to oscillate.

The diode puts a relly heavy load on the tuned circuit and it generates from DC-to-Light. Using the cenrre-tap (GDO2-coil :-) it gave out fewer frequencies, but they were still spurious.

So I coupled the diode to a 10% tapping on the coil and presto !!  A lovely clean 17MHz, and quite a bit of power there, well over a milli-Watt :-)  Now I shall go up in frequency and see what it will do.

Thank you VERY much, you were a tremendous help to me. I should have played more with these when I had the opportunity. But I suppose it is just to get to know the component.

Very best regards from Harry - SM0VPO

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Re: Tunnel diode source

Post by Admin on Thu Feb 09, 2017 4:44 pm

Thank you very much Ivan,
A closer look at the drawing you posted in the previous message also identifies the cathode and anode
Komod#¤%&
Anod#¤%&
So everything is great.

One of the links in the questions about lambda diodes was written in Danish, and I found that I could pick out all the technical words and work out the other with little effort. When I saw the specification in Russian it was easy to pick out the relevant data. It seems that technical documents are easy to read in many languages if you have a technical background  Smile

Thank you very much for all your help. Much appreciated.

Very best regards from Harry - SM0VPO (JO89WO)

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Re: Tunnel diode source

Post by Ivan on Thu Feb 09, 2017 7:32 am

Hi Harry,
I must apologize myself. I am quite fluent in Russian. The "azbuka" (sometimes called "cyrilics") is no problem for me. Therefore I often forget it is not so easy for other people. Drop me a message if you need translation of some datasheet etc.

BR from Ivan

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Re: Tunnel diode source

Post by Ivan on Thu Feb 09, 2017 7:14 am

Hi Harry,
the polarity according to the datasheet is:




Be careful not to exceed the maximum current during experiments.

BR from Ivan

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Re: Tunnel diode source

Post by Admin on Wed Feb 08, 2017 6:19 pm

Hi Ivan,
Yes, I saw the specification. Although the Russian was was a bit difficult to read, I understood the mA and pf bits.

The thing to do is to give them a try. To be honest I am not really interested in frequencies above 450MHz, so I believe that they will do the job ok, especially if I can keep the impedances low. The only thing I cannot decipher is which terminal is which, but that is not a problem. It is just to give it a "suck it and see".

I would be surprised if the advert I replied to is still there. They had only five lots, three sold, then I ordered the last two lots.

Very best regards from Harry

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Re: Tunnel diode source

Post by Ivan on Wed Feb 08, 2017 7:43 am

Hi Harry,
every seller gives additional information according to his taste, of course. The offer I have used probably disappeared after my shopping, as I also bought his last lots. I saved the datasheet prior to closing the offer.
The AI301G has the biggest capacity in the AI301 line of types. This may limit its maximum working frequency. AI301A would be better...

BR from Ivan

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TD Datasheet

Post by Admin on Tue Feb 07, 2017 5:57 pm

Hi Ivan,
The link I saw had very little information, other than AI301G with 10 per packet. 5 packets; 3 sold, so I bought the other two. Perhaps I missed something; this brain seems to have a mind of it's own  Wink
VBR Harry

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TD datasheet

Post by Ivan on Tue Feb 07, 2017 6:42 am

Hi Harry,
what exact type did you buy? The seller I made my purchase at had an original short datasheet scanned on his page. I will try to find data for you, too.
GaAs tunnel diodes should work up to microwaves. 145 MHz should be no problem.

BR from Ivan

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Re: Tunnel diode source

Post by Admin on Mon Feb 06, 2017 4:58 pm

Hi Ivan,

I have just ordered 20 pieces myself and created an account on e-bay :-)
Thank you very much for the tip. I shall look forward to testing them out - hope they can work at 145MHz.
Do you by any chance have a datasheet for them?

BR Harry

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Re: Tunnel diode source

Post by Admin on Mon Feb 06, 2017 4:30 pm

Hi Ivan,
Yes, I must have missed something. Did you buy from a company? or was it private 1-off sale?


For USD19 I will certainly buy those ASAP. that is just wat I want, and a better price than I had hoped for. Do you have a link? Perhaps i can simply search for AI301G GaAs tunnel diodes. I did search Ebay for "tunnel diode" and you know what I saw.


But thank you very much for the response. I will look into that later this evening.
Very best regards from Harry

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Tunnel diodes

Post by Ivan on Mon Feb 06, 2017 8:00 am

Hi Harry,
you must have missed something. Do not be afraid of Russian NOS from military surplus, as their quality was severely observed during the manufacturing process. I have bought 20 pcs (2 lots per 10 pcs) of AI301G GaAs tunnel diodes on eBay for 19,34 USD incl. postage to Czechia just a while ago. I hope they will be better than your 78L05 Suspect .

VBR from Ivan OK1SIP

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Re: Tunnel diode source

Post by Admin on Sun Feb 05, 2017 12:40 pm

PS - I found another source of the 1N3149 but one diode is $13 plus $13.50 postage. But that's only 26.50 for one device.
/H

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Tunnel diode source

Post by Admin on Sun Feb 05, 2017 12:26 pm

Does anyone know where I can get tunnel diodes at a reasonable price.

I found one 1N3149A (50mA) on e-bay at $6 but the company wants $22 for postage. If I try to Google for tunnel diodes then I just get loads of datasheets.

I did find one diode in Russia, but they want $80 for it.

BR Harry

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