Listening to FM broadcast with HAM IT UP

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danielSDR
Posts: 3
Joined: Sun Nov 10, 2019 8:03 pm

Listening to FM broadcast with HAM IT UP

Post by danielSDR » Sun Nov 10, 2019 8:07 pm

I have a Nooelec sdr and a Ham It Upconverter installed and working (on linux)

If I bypass the Upconverter I can receive FM radio strations no problem example : 101.7 FM

If I go through the Ham It Up as I take it I should add 125mhz to the 101.7 which is 226.7Mhz but there is nothing there...

Any help would be apreciated.

Thank you

alanzfq
Posts: 66
Joined: Thu Oct 04, 2018 11:18 am

Re: Listening to FM broadcast with HAM IT UP

Post by alanzfq » Mon Nov 11, 2019 7:41 am

Any good converter would have a LPF in front of it. No VHF.
Alan

danielSDR
Posts: 3
Joined: Sun Nov 10, 2019 8:03 pm

Re: Listening to FM broadcast with HAM IT UP

Post by danielSDR » Tue Nov 12, 2019 1:12 am

I don't understand your reply...

Aussie Susan
Posts: 37
Joined: Sun Jul 31, 2016 1:55 am

Re: Listening to FM broadcast with HAM IT UP

Post by Aussie Susan » Tue Nov 12, 2019 1:56 am

When you mix two signals together, you get the sum and the difference as a result. A Low Pass Filter (LPF) will remove the sum (which will be the higher frequency) and leave the lower one.
The two signals that the 'Ham It Up' will be mixing are the 125MHz local oscillator signal and the incoming MF/HF signal which can be 30MHz and below. Therefore, assuming a 30MHz signal the two output signals will be at 85MHz and 155MHz. Now the lower frequency is in the bottom end of the FM range of frequencies while the higher is in the middle of nowhere. However the LPF will remove the that higher frequency (to some extent) and leave you with the 85MHz signal.
Looking at (say) the 20 meter band which has a frequency of around 14MHz, the sum and difference frequencies will be 111MHz and 139MHz. Again you want the lower frequency which is just a little above the FM band but if you have an SDR then it will handle that for you.
The secret is in the name of your device: 'Ham it Up' - the 'Up' refers to it being an up-converter that moves lower frequencies to a higher frequency range.
Susan

alanzfq
Posts: 66
Joined: Thu Oct 04, 2018 11:18 am

Re: Listening to FM broadcast with HAM IT UP

Post by alanzfq » Tue Nov 12, 2019 8:52 am

Putting it simply. (Well trying!)

A LPF (A Low Pass Filter ) is inside the converter.
Normally it will be just after the antenna socket, greatly reducing signals above 30MHz from reaching the mixer.
You do not want to hear signals above 30MHz when you use the converter. You would hear both HF and any corresponding VHF signal at the same time.
The LPF stops VHF signals, to receive VHF the converter has to be switched out so you receive VHF directly.
It seems your "HAM IT UP " is working well.
Alan

danielSDR
Posts: 3
Joined: Sun Nov 10, 2019 8:03 pm

Re: Listening to FM broadcast with HAM IT UP

Post by danielSDR » Tue Nov 12, 2019 1:38 pm

Thanks

aurgathor
Posts: 84
Joined: Wed Apr 25, 2018 8:14 am

Re: Listening to FM broadcast with HAM IT UP

Post by aurgathor » Wed Nov 13, 2019 5:59 pm

As per https://www.nooelec.com/store/ham-it-up.html :
"Frequency capability of 100kHz-65MHz in upconvert mode"
and the FM band is well above 65 MHz.

While I haven't seem one, I bet there is a 65 MHz low pass filter on the ham-it-up's input, and that should explain why it's not working on the way you expect it to work. You could get a mixer from Pasternack or some other place and they could work that way because they don't have a filter unless you add one.

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