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Author Topic: UHF on a VHF Rig (updated)  (Read 4695 times)
VU2NAN
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« on: November 07, 2013, 10:18:32 AM »

Please do check this out.

http://nandustips.blogspot.in/2011/02/uhf-on-vhf-rig.html

73,

Nandu.
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AB9NZ
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« Reply #1 on: November 09, 2013, 06:10:57 PM »

What a beautiful little transverter! Thanks for sharing Nandu.
     73 de Tom AB9NZ
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VU2NAN
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« Reply #2 on: November 09, 2013, 08:49:37 PM »

Hi OM Tom,

Many thanks for the compliment.

73,

Nandu.
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G3RZP
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« Reply #3 on: November 10, 2013, 05:22:24 AM »

Just be careful that the radiation at 120MHz from the 70cms antenna - there will be some - doesn't give a problem for aircraft. Also, any strong FM BC stations in 94 - 96 MHz can mix with the 4th harmonic  and come out in 2m.
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VU2NAN
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« Reply #4 on: November 10, 2013, 11:11:48 PM »

Hi OM Peter,

Your point is well taken, but what would be the extent of unwanted radiation with the DC input to the oscillator being less than 70mW?

Many thanks.

73,

Nandu.
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G3RZP
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« Reply #5 on: November 11, 2013, 05:57:07 AM »

Depends on the 70cm antenna performance at 120 MHz - and its impedance at 120MHz and the leakage inductance of the tuned circuit etc. In Europe, all the receiver radiation is required to be -57dBm conducted to the antenna for frequencies below 1GHz. That probably means getting some 60dB of attenuation...

More of a problem is the FM broadcast breakthrough if there are strong local signals in 94 - 96 MHz - also breakthrough from DAB operating around 216 MHz.  Adding a quarter wave short circuit coax stub at 70cms across the input would help enormously - about 12cms would do it with solid polythene dielectric coax. It would help with radiation, too.
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VU2NAN
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« Reply #6 on: November 11, 2013, 06:50:26 AM »

Hi OM Peter,

Thank you very much for your inputs. They are eye opening!

73,

Nandu.
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G3RZP
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« Reply #7 on: November 11, 2013, 12:16:57 PM »

Nandu,

You are welcome! Good luck.

73


Peter G3RZP
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