Questions tagged [hf]

The frequency range 3-30 MHz. HF radio waves often propagate by bouncing off the ionosphere, allowing communication between continents. This tag may also be used for questions about the 160 meter band (1.8 MHz), which while not HF is often referred to as such due to its similar propagation.

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6.765 - 6.795 MHz ISM band for prototype testing

Not strictly a ham radio question, but I figure this is the most knowledgable community to ask. This question pertains to Canada, specifically. If I were wanting to build a prototype for a commercial ...
Jordan's user avatar
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2 votes
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What is the best way to ground a whip antenna in a hotel room?

We have a 102" CB whip antenna cut for 10 meters. We're staying in a hotel and trying to figure out the best way to ground this antenna. Right now we're using a pile of wires on the floor, but we'...
kj7rrv's user avatar
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2 votes
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What could cause an Icom IC-756 Pro II to suddenly stop transmitting?

My HF radio (Icom IC-756 Pro II) suddenly won't receive or transmit. I recorded the sound it makes when receiving and uploaded it to https://w7bkg.org/wiki/File:Radio_Issue.wav . It sounds the same on ...
kj7rrv's user avatar
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1 vote
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How do I test if three turns are better than 4 turns?

I built a class ab amplifier kit to use with my qrp radio. 2 watts in creates 50+ out. This was the pa 70 amplifier kit. It is a kit with no instructions, but a whole suite of internet videos and ...
Jeffrey Edward Messikian's user avatar
1 vote
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Need help in the fabrication of an UHF power amplifier

I recently decided to conceive a 10W class 446MHz amplifier. I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier : SKY65162 to amplify the signal to ...
Wireless Learning's user avatar
1 vote
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66 views

HobbyPCB IQ32 SDR Data modes cable?

has anyone DIY datamodes cable for HobbyPCB IQ32 SDR ? Im thinking of using SPKR/MIC/PTT port and expose it either towards external USB soundcard (or USB soundcard stick), or directly to laptop USB. ...
Vladimir Ivkovic's user avatar
1 vote
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120 views

HF propagation prediction using machine learning

Anyone out there know of or developed s/w to predict HF conditions using ML?
KG6ZIC's user avatar
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1 vote
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Parasitic inductance of relay contacts

I need to switch a bank of filters operating on bands from about 2MHz to 30MHz. The parasitic series inductance of the relay contact system will have an effect on the performance of my system. ...
Brian K1LI's user avatar
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homebrew t match atu issues

my homemade tmatch atu is ok on 80+40m but seems too have too mutch inductance on the bands above 40m,it has a 50mm/20cm roller coaster,i have a 40m doublet+ 4-1 balun+ common mode choke fitted in the ...
paul .a larner's user avatar
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50 Ohm Active Termination

I'm looking for a circuit topology that has unity gain, a 50 Ohm resistive input impedance, a 50 Ohm resistive output impedance, and here is the kicker, at least 60 dBm OIP3 over a 2 - 30 MHz HF ...
W6DSR's user avatar
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