12

It doesn't sound like you're doing anything wrong. Most likely, you are simply only hearing strong stations; broadcasters put much more power into their transmissions than amateurs are legally allowed to, so you can hear them over a much wider range. Advice on the practice of listening: For finding signals, first of all, always use SSB. Even if it's the ...


10

I did a bit more reading, and it seems that the new version of the firmware meant I needed to use a different chirp profile. The solution that worked for me was to find a factory image from a radio with the firmware version I have (which Chirp reported), then import my channels via csv, and clone that resulting image onto the radio.


6

I signed up here just to reply to this great (the only one I could find on the internet) question/experience that helped me with an identical problem. I was so close to giving up when I read this thread and went to examine the component that looks like a coin battery (as the original poster described) and having owned a sucking hakko soldering gun, i ...


6

Without any radio shack tools? Connect a bulb to the antenna output to indicate RF. Two times 12 volt 5 Watt in series (rear light of car bulb) can indicate RF. Reduce RF power before hitting the TX-button. Problem is similar (looking) to the problem with an IC-720 that I owned. Reason was the rotary switch used for the band pass switching. Poor contacts. ...


5

While the other answer is quite detailed, this one is much shorter and specific: I purchased and installed an aluminum RF shield for the dongle. The noise floor is significantly lower as a result! I was able to drop it even further by adding a ferrite bead to the USB cable. (I was already using a 10' extension to get it away from the computer.) Update: ...


5

“Sensitivity” isn't all that well-defined. Insofar as it is, you might as well just think in terms of noise, because there is always a noise floor and it's always what determines the weakest signal you can receive. The most direct way to deal with noise is to make the signal stronger than the noise. This means improving your antenna: making it more ...


5

Tecsun is very similar to Baofeng in that anybody selling them expects a certain number of DOAs and other failures. They already know that QA on those rigs is directly reflected in the price. In the past I have had good success with getting vendors of like this to replace the radio body (no battery or antenna) simply by writing to them. I have gotten ...


5

No power light could just be a burned out bulb or dead LED (I have a 259B...don't recall if the power button ever lit up). If you don't have anything connected to the antenna connector, then it's perfectly normal for the SWR meter needle to go all the way to the right because it's indicating a high SWR. Put a 50 ohm dummy load on the analyzer and see what ...


4

It might be harmonics of the oscillator, as you suppose, but it also might be that any mixer doesn't only produce the difference frequency of its two inputs ($|f_\text{RF}-f_\text{local oscillator}|$, here), but also higher-order intermodulation products (like $|2f_\text{RF}-f_\text{LO}|$ and $|f_\text{RF}-2f_\text{LO}|$). I think I've posted multiple ...


4

I'm not familiar with the exact behavior of that model of radio (and the manual was not very helpful), but a possible explanation in general is that you have CTCSS/DCS squelch enabled, and the repeater is not using the same tone/code. However, for this to match the observed behavior it would have to be the case that a squelch setting of '0' disables tone ...


4

HackRF has three amplifiers in the receive section. The first is a low noise amplifier (LNA) with fixed gain of 14 dB. The second is an Intermediate Frequency (IF) LNA with gain that varies from 0 to 40 dB. Finally, the baseband amplifier gain can be varied from 0 to 62 dB. On the transmit side, there are two amplifiers. The first is an IF LNA with gain that ...


3

While I wouldn't rule out old capacitors or whatnot, if it's anything like some of the radios I've played with through the years, the solution might be a simple mechanical one: can you open it up enough so that you can hold the dial from moving while gently nudging the linkage from the FM circuit tuning mechanism until it lines up?


3

I took it apart and found a transistor that had been blown apart, pictured below (the black one with its metal innards showing), likely from a scenario described by @rclocher3. This is the NPN transistor that supplies voltage to the blue PNP transistor and should be switching based on its base input but instead is supplying a constant 5V. No surprise there, ...


3

The most likely scenario is that all four radios have the same problem. It's possible that the problem is a manufacturing defect, but that's unlikely, especially if you got the radios from different sources. It doesn't sound like a hardware problem, because the radios hear fine when the menu is open, so the problem sounds like a firmware or configuration ...


2

If your antenna is hanging down the side of the building that may be your very problem! Most DXing on HF is done on horizontal antennas. If yours is vertical then you be getting only a sliver sized cross section of the horizontal signals. The station you did pick up may be driving a vertical antenna. The cheapest way to test this is to put up a ...


2

Try reducing the power and see if that helps. If it lets you transmit longer then the battery needs to be replaced. If it shuts off right away at low power then you may have a bad final or other malfunction in the rig itself. If you suspect the battery after this test try to borrow one and see if it does the same thing rather than buy a new one. Unless ...


2

Multimeters are generally used to measure AC volts at line frequencies, i.e. 50/60 Hz, and yours is almost certainly not accurate at 1 GHz. Similarly your multimeter's DC volts setting is designed to measure static DC volts, not the DC bias of a 1 GHz signal. To sum up, your multimeter measurements are probably completely meaningless. If you want to see ...


2

I have just joined so have to answer instead of commenting (not enough reputation yet). I have one of these receivers and know a little about them (I have to say it performs excellently and is very nice to use). They are now fairly old so are a bit prone to dry solder joints and dry caps. There are quite a few plugs/ connectors that can occasionally give ...


2

I had the same issue. I adjust the Azimuth every day, then sometimes it fails between 15-20 degrees. Then I replaced the regulator with a new one. Now it is ok.


2

I assume you have extensively bench tested the kit and have not found any problems. Having several years of experience with high altitude radios in the Alps, I would suspect that you are getting static build-up on the antenna that is glitching the radio. A Polyphasor, or equivalent, to ground can mitigate static build up. Failing that, a couple of megohms ...


2

Everything works very well, but on some frequencies I hear loud AM broadcast stations. I think this is caused by harmonics from the VFO, but I am not sure. What you're possibly hearing is intermodulation distortions created by your receiver from the mixer and amplifier. A local AM broadcasting station has high radiated power, making the problem even worse. ...


2

After reverting MARS/CAP mod everything works as expected. I don't know whether the problem was caused by the mod per se or maybe just one of FCC cables was a little bit misplaced when the mod was made.


2

Menu option for ssb filter (38?) should be "off", if no filter.


2

Unless you tried to transmit without an antenna, it should be fine. If the radio is in receive mode without an antenna, it won't hurt it. But if you transmit without an antenna, especially at high power, the high SWR could damage the final amplifier in the radio.


2

In the keyer, PNP transistor Q4 should be on when the keyer is supposed to be keyed. I assume that the transceiver's key jack goes to a CMOS high-impedance input and has a pull-up resistor, and that the key jack's sleeve terminal is tied to ground. If all that is correct, and if the keyer is working correctly, then the positive output of the terminal ...


2

There are three receive gain stages in the HackRF one. Two of them are on the MAX2837 chip (the ones controlled by "LNA gain" and "VGA gain"), and the third is the MGA81563 preamp, which is either on (+14dB) or off (+0dB), and controlled by the "amp" toggle. You have indeed blown the MGA81563. I did the same thing to one of mine ...


2

Short version of the answer: VFO B was USB, not USB-D. After manually changing VFO B to USB-D it worked. Longer version: I went back to testing this again and finally noticed that the mode indicator was changing from USB-D to USB every time the WSJT-X keyed up the radio. Apparently telling WSJT-X to use data mode only ensures the radio is using data mode ...


1

SSB requires a signal from the microphone: only when you are talking there is a signal generated. For CW you need to connect a morse key or paddle to have output signal. When FM and AM are operational there is nothing wrong with your power amplifier. In case of a defect: check the microphone by listening to the AM or FM output signal and when that is ok and ...


1

FYI C4FM is not allowed below 29 Mhz. This is because it is a wide band modulation and uses more than the allowable bandwidth for HF band transmission. Straight FM is not allowed below 29 Mhz for the same reason.


1

That's an oddball receiver, employing a so-called Polyakov mixer. Its local oscillator is supposed to run at half the received frequency. For 80M, the local oscillator runs at about 1.8 MHz. The RF amplifier ahead of the mixer should be very linear...this one is biased weakly, and could easily distort when presented with strong input signals. This type ...


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