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7 votes
Accepted

How to reduce VFO sensitivity to the hand capacitance?

As mentioned in the comment by henryflower, make sure that the shaft (and thus the frame) of the variable capacitor are grounded. You need to use rubber mounting grommets around the screws which bolt ...
Andrew's user avatar
  • 3,685
6 votes

Repairing a Tecsun PL-660

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 ...
vincenzo's user avatar
5 votes

Faulty MFJ-259 - meter hits end stop on power up

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 ...
imabug's user avatar
  • 689
5 votes

Repairing a Tecsun PL-660

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 ...
SDsolar's user avatar
  • 2,089
5 votes
Accepted

BF-F8HP radios do not receive on 2m unless menu is open

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 ...
rclocher3's user avatar
  • 9,222
4 votes

What causes my direct conversion 80m receiver to receive AM broadcasts?

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 ($|f_\text{RF}-f_\text{local oscillator}|$, ...
Marcus Müller's user avatar
4 votes

Squelch never seems to "open the gate" on Wouxun KG-UV9D

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 ...
Kevin Reid AG6YO's user avatar
  • 24.6k
4 votes

The amplifier does not work for hack rf one

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 ...
Radio Blogs's user avatar
4 votes

How to reduce VFO sensitivity to the hand capacitance?

Circuit looks OK. Note that the highest impedance point in this circuit is near the box open end. RF voltage here is highest in this oscillator, and is susceptible to coupling out the top. A shield ...
glen_geek's user avatar
  • 931
3 votes
Accepted

Connecting a Katsumi Elekey EK-150 to my transceiver

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 ...
Edward Anderson's user avatar
3 votes
Accepted

The amplifier does not work for hack rf one

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, ...
hobbs - KC2G's user avatar
  • 12.4k
3 votes

Erratic behavior on Baofeng UV-5R Plus

It seems to me that you have a bad radio, that is to say a radio with one or more faults in it. You shouldn't be getting the sensation of a shock or heat, and those are possible indications of a ...
rclocher3's user avatar
  • 9,222
3 votes

Why does my transmitter spam the SDR waterfall with this strange pattern?

This is not strange at all. But depends on the transmitter, transmit power level, receiver, and the how close the two antenna's are situated. Electronic circuits are linear only over a certain finite ...
hotpaw2's user avatar
  • 13.3k
2 votes

Baofeng UV82-HX charger problem

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 ...
user5922's user avatar
2 votes

Signal generator giving DC output?

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 ...
rclocher3's user avatar
  • 9,222
2 votes

Issue with Icom R-71A

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 ...
PeterH's user avatar
  • 311
2 votes

Yaesu G-5400B rotator controller problem

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.
kadri TA1D's user avatar
2 votes
Accepted

Kenwood TH-D72 Freeze on Splash Screen

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 ...
Glenn W9IQ's user avatar
  • 18.6k
2 votes
Accepted

Yaesu FT-991A: FM and C4FM modes don't work on HF bands

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 ...
Aleksander Alekseev - R2AUK's user avatar
2 votes

Yaesu FT-817 Won't transmit Dig, SSB or CW

Menu option for ssb filter (38?) should be "off", if no filter.
Joe Shmoe's user avatar
2 votes

What causes my direct conversion 80m receiver to receive AM broadcasts?

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 ...
比尔盖子's user avatar
2 votes
Accepted

Simple AM Radio Troubleshooting

I'm not sure how to give proper credit but I figured it out with your help. I'd like to thank all of you for helping me. It really means a lot even though it was a bit rough. Don't push away newcomers....
Derpy's user avatar
  • 95
2 votes

Kenwood TS 520 S Meter accidentally run without an antenna connected

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 ...
user10489's user avatar
  • 6,320
2 votes

Connecting a Katsumi Elekey EK-150 to my transceiver

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 ...
rclocher3's user avatar
  • 9,222
2 votes

Where can I find a service manual for the TECSUN PL-660 to replace the failed circuit board flex cable myself?

Try this link and check if it is what you are searching for: https://elektrotanya.com/tecsum_pl-660_schematic.pdf/download.html Note: Google Safe Browsing deems this site as 'No unsafe content found'. ...
essential555's user avatar
2 votes
Accepted

Why is IC-7300 transmitting at zero power in "Rig" split mode with WSJT-X and FT8?

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 ...
QuantumMechanic's user avatar
2 votes

Erratic behavior on Baofeng UV-5R Plus

I think you have a loose wire in there somewhere. It's probably the ground or center lead between antenna and amplifier. The bursts of static might be from the wire making contact or not, or contact ...
Jack0220's user avatar
  • 373
2 votes

Did I brick my Yaesu ft-780r

The manual for this radio is quite helpful in that it has a theory of operation, block diagram and complete schematics in it. This radio doesn't have non-volatile memory, so simply removing all power ...
John's user avatar
  • 156

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