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1500 questions
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2 answers

Can anyone identify this military radio?

Hoping someone can identify the following military radio. I spotted it at the curb and decided to make it a land-fill diversion project...
radiorabid
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5 answers

Why a capacitor is needed in Fuchs antenna?

I tried to understand the physics of Fuchs antenna and there is one thing that I don't quite understand. This is probably a very silly question, but I spent a lot of time looking for an answer (books, online) and didn't manage to find it. Modern…
Aleksander Alekseev - R2AUK
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6 answers

EFHW works only on one band - what am I missing?

I tried to build a multiband EFHW antenna as described in articles by PA3HHO, PD7MMA, G0KYA and many others. I decided to start with a short 40/20/(15?)/10 meters version without any loading coils. Surprisingly, no matter what I tried I didn't…
Aleksander Alekseev - R2AUK
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5
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3 answers

Heathkit SB-102 Plate Current out of control

I bought a "technician special" Heathkit SB-102 transceiver. Everything seems to work well until I attach a dummy load and try to go through the "initial tune up" procedure in the manual. At the point where I switch the "Mode" to "Tune", instead of…
Zeiss Ikon
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2 answers

Why is my calculation for added length of coax for a double cross antenna different to everyone else's?

I'm an amateur amateur radio enthusiast finally building my own antenna, and have decided on a double cross antenna, with the goal of pulling data from NOAA satellites. Four coax cables, two of length x, and two of length x+λ/4. For 137 MHz, the…
zeph
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2 answers

Better SWR bandwidth

Good day, I have a Kenwood TS-480HT with a Wolfriver coil and a stainless steel whip in my car. I find that on 40 meters I can get the SWR at around 1.4 (using an MFJ 269) at 7.1000 MHz. But the SWR goes high (2.5 to 3.0) very quickly if I go closer…
Danny
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1 answer

How should two loopstick antennas be placed w.r.t each other to maximize transmission?

An engineer working in the RF industry told me something which left me very confused: He said that a pair of emitter-receiver beacons get the clearest signal when loopstick antennas in the receiver and the emitter are parallel. That is, when both…
Dugas
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3 answers

Why does no one use a Buddipole as an Inverted V?

I have been looking at the Buddipole, and I've seen the most popular configuration is as a standard dipole with the arms parallel to the ground. I've also seen it configured as an upright V, as well as configured in a sloped condition. But I haven't…
SandPiper
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2 answers

How do I interpret the FCC ground conductivity map files?

The FCC has .seq files that show ground conductivity which it makes available for download. Unfortunately, there doesn't appear to be any documentation that comes with the files, or even headers. I can make an educated guess that there are two…
user3486184
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4 answers

How does a receiver know the exact frequency in the channel to "listen to"?

I am reading about how radio communication works and I have an unanswered question. We have wideband channels with 25kHz of radio spectrum. The transmitter modulates a signal and sends it. The receiver that captures that particular channel and…
kkris1983
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3 answers

Feeding a folded dipole

Can I feed a folded dipole constructed of hollow tubing by threading coax through the element to create both an impedance transformation and balun? I have fed coax through the tubing of the dipole from a point opposite the feed point and soldered…
R Johnson
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1 answer

Can I use CHIRP for programming a Baofeng DM-5R?

I can't find my Baofeng DM-5R in the CHIRP list of supported radios. I've been told that I should try by telling CHIRP to assume a different radio from the DM-5R - perhaps the UV-5R!? Do you know if this is a feasible option? I am able to manually…
Phil Carter
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3 answers

Only noise, no signals whatsoever on HF

Last night there was a power outage at home. I was able to see a LOT of stations on 20M (FT8). As soon power returned, all of them disappeared. You can see in the waterfall very clearly when power returned: The odd thing is, noise is around 7 here…
hjf
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3 answers

What is the proper way to electrically wire in a loading coil to a vertical antenna?

I am trying to put together a vertical pole style antenna with a loading coil housed at the base using a plan very similar to the one described in this ARRL article. I am trying to understand how to electrically wire it though. For convenience, the…
SandPiper
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1 answer

Is a gradual power-up recommended for non tube based radios?

It used to be that if you wanted to power up an old tube radio, you'd use a variac and gradually bring up the line voltage to avoid damage to the radio. Is this needed or suggested for transformer powered semiconductor radios that have been sitting…
Adam Davis
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