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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 18th Oct 2021, 8:00 pm   #1
Paul Smith
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Smile Datong UC-1 HF/VHF Converter.

Hi.

Thank you for allowing me to use this site.

I bought a Datong UC-1 HF/VHF receiver converter, IF out 28-30 MHz also 144-146 Mhz. The VHF is working very well but HF is very poor even with my RF sig gen. I have all the basic info from the Datong archives. I think maybe it has been flashed with a transmitter and this has caused damage to the HF side. Any info would be very helpful. I would like to get it up and running as I use it on RX on my 28-30 MHz receiver.

Thanks for looking, Paul M0KBD. 73's.

Last edited by Station X; 18th Oct 2021 at 8:27 pm. Reason: Readbility.
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Old 19th Oct 2021, 12:20 am   #2
Julesomega
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Default Re: Datong UC-1 HF/VHF Converter.

Isn't it supposed to convert HF to the 2m band? Is it the same unit as this?
https://www.radiomuseum.org/r/datong..._converte.html
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Old 19th Oct 2021, 12:44 am   #3
Bazz4CQJ
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Default Re: Datong UC-1 HF/VHF Converter.

My recollection is that Datong were very fond of using 40673 dual gate MOSFETs and it was certainly very easy to send those to an early grave. Never seen a piece of kit like that before.

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Old 19th Oct 2021, 6:22 am   #4
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Default Re: Datong UC-1 HF/VHF Converter.

The UC-1 is rather special. The up conversion is actually performed by a parametric amplifier! It uses varactor diodes as pumped, fast, variable capacitors. The local oscillator pumps the diodes and varies the resonant frequency of a tank. You get frequency mixing, but you also get gain. The gain being proportional to the frequency up-conversion ratio according to the Manley-Rowe law. Around the varactor circuit there have to be resonators at both input and output frequencies as you'd expect, but there also needs to be an idler tank at an image frequency to make it work.

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Old 19th Oct 2021, 8:40 am   #5
Paul Smith
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Default Re: Datong UC-1 HF/VHF Converter.

HI.

Thank you everyone for the use of the forum, now a member.

The Datong UC-1's IF output is both 28-30 MHz and 144-146 MHz. I will have a look at the components and look various site for replacements. The unit was built in the 1970's. I also have 2 times Datong VLF converters and an FL3 filter unit.

I operate a Kenwood TS2000X but love vintage radio equipment. Long live the AR88.

73's Paul M0KBD.
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Old 19th Oct 2021, 12:21 pm   #6
G4BZI Roger
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Default Re: Datong UC-1 HF/VHF Converter.

Hi Paul,

If you Google "Datong archive" you will find a site that has info on the UC1 as well as many other Datong products. The HF input to the UC1 uses a dual FET - type E430 (Siliconix?) - not sure where you'd find a spare though if it has failed!
Good luck.
Roger
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Old 20th Oct 2021, 4:15 am   #7
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Default Re: Datong UC-1 HF/VHF Converter.

Quote:
Originally Posted by Radio Wrangler View Post
The UC-1 is rather special. The up conversion is actually performed by a parametric amplifier! It uses varactor diodes as pumped, fast, variable capacitors. The local oscillator pumps the diodes and varies the resonant frequency of a tank. You get frequency mixing, but you also get gain. The gain being proportional to the frequency up-conversion ratio according to the Manley-Rowe law. Around the varactor circuit there have to be resonators at both input and output frequencies as you'd expect, but there also needs to be an idler tank at an image frequency to make it work.

David
Ah, that old trick

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Old 25th Oct 2021, 1:08 pm   #8
Paul Smith
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Default Re: Datong UC-1 HF/VHF Converter.

hi thanks for the info on this datong uc 1 hf/vhf converter i dont have the test gear to sort out the hf side and geting the parts but it works great on 144 all mode with my mono band 28/30 mhz as for receiving the 28/30 mhz will scan all day and it is a much better than any other 144 converters thank you for all your replys stay safe paul m0kbd 73s
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