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1 | Original Projects and Builds / Other Builds and Projects / Re: 7591 Amp Build (from Rowe/AMI R-4359) on: May 29th, 2023, 8:57am |
Started by Administrator | Post by Administrator | |
In my last post, I stated that this project was "essentially" complete. Now I will demonstrate why I didn't just say "compete". After some use, and testing, I decided that I was not happy with the VFD (Vacuum Fluorescent Display) Spectrum analyzer that I had purchase and installed in this amplifier. Here are some specific complaints I had about the VFD SA:
After some research of available bare VFD SA boards available on AliExpress, I found out the board I had bought was essentially "counterfeit", or a poor quality version of a board known as "AK2515". On big hint is that the knock-off, or poor quality VFD's do not even specify a frequency range in the AliExpress advertising. But even "real" AK2515 boards still have the clock mode. A little more research lead me to this unit from Douk Audio: ![]() This unit does have a full set of advertised specifications. It does not have a clock mode, and while there is no question that Douk Audio is still a "Chi-Fi" company, I at least trust them to have a little better quality than most of the other Chinese vendors. The board still needed some connector modifications, and I had to drill a new hole in one of the support brackets, I was able to install the Douk Audio VFD into the amplifier without too much difficulty. The new display is slightly larger, and noticeably brighter and "bolder" than the previous one. I will point out that I still consider all of these to be highly inaccurate for actually measuring audio frequency -- especially in stereo display mode. First, there are 25 bars, and there is no "blank spot" or skipped bar in stereo mode. This means that the left channel has 12 bands and the right channel has 13 bands. Furthermore, these displays don't actually have an analog filter for each band. They use a microprocessor to do DSP and scan the display. The result of all of the above is that even if the same pure sine wave signal is fed into both channels, the left and right channels will not display the same levels at the same band anyplace in the audio spectrum. That said they still provide a visually interesting visualization of the music, and they have to the bright, and attractive color that only VFD's can provide. |
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2 | Linuxslate.com Reviews & Commentary / Review Discussions / Re: Unbranded Chinese Pocket Geiger Counter on: May 12th, 2023, 9:44am |
Started by Administrator | Post by Administrator | |
UPDATE: There already seems to be a newer version of this Geiger Counter/Ionizing Radiation Detector. Look carefully at the ads for the following Changes:
I strongly recommend purchasing this new version over the version I reviewed. I am not aware of any software/display changes at this time. If you have additional information on this new version, or would like to send me a complimentary unit for review, please send me an email at "john" at this domain (linuxslate.com). |
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3 | Linuxslate.com Reviews & Commentary / Review Discussions / Re: Mini Review DOLCOM GP328 PLUS and discussion on: May 3rd, 2023, 2:00pm |
Started by Administrator | Post by Administrator | |
I have a few more comments about my DOLCOM GP328 PLUS. Continued from the 1st Post Pros:
Cons:
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4 | Linuxslate.com Reviews & Commentary / Review Discussions / Re: Mini Review DOLCOM GP328 PLUS and discussion on: Apr 22nd, 2023, 9:49am |
Started by Administrator | Post by Administrator | |
I in the first post of this thread, I posted to following hypothetical question: Has this (cheap) old Cynic finally found the Chinese Radio that fits his needs? --- and The Answer is -- Yes. The DOLCOM GP328 PLUS is now my EDC (Every Day Carry) HT. My HamGeek FB-8, Reviewed Here, will go into my bin of things to sell at the next Hamfest. My Wouxun KG-UV9D Plus (See this thread about programming the Wouxun KG-UV9D Plus from a Linux PC) is a more serious, and more professional radio, but without USB charging, and given that the DOLCOM GP328 PLUS has all of the features I actually use, the Wouxun KG-UV9D Plus will probably just remain in a drawer, and eventually join the HamGeek FB-8 in my Hamfest display case. If you are a serious Ham operator looking for your main HT, you probably aren't (should not be) looking at $40 off-brand radios. If, however you are looking for a broad receive HT to have in your car, truck, backpack or pocket, and you may, on occasion slip off into the GMRS bands, business bands, or other places*, this radio will fit the bill -- and not a lot of bills. It would also make a great gift or incentive for a young person to study and get their ham license. *Operating this or any transmitting device outside of the bands you are licensed to transmit on is illegal. Setting a radio that is not FCC approved for GMRS, FRS, or specific business bands to those frequencies, and then transmitting is also illegal regardless of license. This radio did not come with any FCC markings, and thus could be confiscated in the United States regardless of use or non-use. This radio must only be used by a licensed ham, and must be use responsibly. |
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5 | Linuxslate.com Reviews & Commentary / Review Discussions / Re: Ailunce HS2/Radioddity QR20/Q900 SDR Transceiv on: Apr 19th, 2023, 8:37pm |
Started by Administrator | Post by Administrator | |
Quick Firmware Test Results. Note: Check back on this page for updates as I use the FW. I just wanted to post something quickly. I installed the latest Firmware on the Guohe Electronics Download page as of this writing. Link: HW3.0&4.0 SW 3.4.0.rar. Resulting Archive: SW3_4_0.zip Date (as listed in the log file mentioned in the previous post): 2023.4.16 Observations:
More Observation after Trying FW 3.4.0:
NOTE: This is a website devoted to Open Source Software. If Guohe Electronics would release the source code for this radio under and appropriate Open Source License, the developer community could probably fix most of these issues in a day. We would also likely have dozens of additional apps for this radio -- for example aircraft ADS-B Tracking. Note that open source code for decoding is already available for decoding ADS-B signals. |
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6 | Linuxslate.com Reviews & Commentary / Review Discussions / Re: Ailunce HS2/Radioddity QR20/Q900 SDR Transceiv on: Apr 19th, 2023, 7:45pm |
Started by Administrator | Post by Administrator | |
NEW Firmwares Again, there seem to be new firmwares on the Guohe Electronics Download page. Version 3.1.4 dated 22 August 2022 seems to have been removed. I have reported the fact that some (but not all) of the previous FW versions seem to disappear. Although the link you click to get the FW files Says e.g. "HW3.0 SW 3.3.2.rar", the resulting file is actually a .zip file. Again, the zip contains only the raw binary FW-NEW.bin file -- No release notes, instructions, etc. There is also a Q900-FW-V3 log.rar, which in this case does result in a .rar file being downloaded. This archive contains only a .txt file. The contents of this log file is listed here: Code: Date: 2023.4.16 FW-V3.4.0 1. Fix the issue of insufficient frequency offset in NFM mode. Date: 2023.3.20 FW-V3.3.2 1. Fix incorrect DMR call boot mode. 2. Add MPU6050 drive. 3. Fix the problem that the channel cannot be saved. 4. Add write channel function. 5. Add DMR setup menu shortcut keys 6. Support direct frequency operation and relay operation in DMR mode. 6. Increase compatibility with Hytera and Motorola interphones. Date: February 22, 2022 FW-V3.1.8 1. Solve the problem of insufficient NFM mode downward adjustment system. 2. Add mouse drive, mouse can be used as encoder. 3. Increase GPS data output through serial port. 4. Resolve channel storage data errors. Date: February 22, 2022 FW-V3.1.4 1. Solve the problem of insufficient NFM mode downward adjustment system. 2. Add an AFO interface to output different audio in different modes for easy access to external speakers. Date: 2022.6.7 1. Switch Bluetooth input to headset audio, and when Bluetooth FT8 is enabled, the speaker can be turned off to play FT8 without affecting each other. Date: 2022.5.4 FW-V3.1.1 1. Solve the transmission frequency offset problem. 2. Open the user calibration interface to provide frequency, voltage, and S-meter calibration. 3. Solve the problem of no sub tone in NFM mode transmission. 4. Add new local oscillator driver support. Note that the links refer to a HW3.0&4.0 SW 3.4.0.rar. [Emphasis added]. As of this writing, I do not understand the reference to a HW 4.0. Note that a previous Firmware incremented my HW version from 2.0 to 3.0, so I am assuming that one or both of the latest FW's will change the HW version to 4.0. However, some advertising does mention different actual hardware versions. I will try the available Firmwares, and report any significant findings. |
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7 | Linuxslate.com Reviews & Commentary / Review Discussions / Re: Mini Review DOLCOM GP328 PLUS and discussion on: Apr 16th, 2023, 12:36pm |
Started by Administrator | Post by Administrator | |
DOLCOM GP328 PLUS RF Power Output Testing Test Set-up: DOLCOM GP328 ----> Female SMA to Female SMA adapter ----> Male SMA to Male SMA jumper cable ----> 60 DB SMA attenuator ----> RF Explorer High-Z Input RF Explorer set to appropriate band, Offset DB set to +60. An on-line calculator is used to convert the dbm value observed on the RF Explorer to Watts. NOTE: Unit operating from a source of 5VDC applied to the USB-C port on the battery. Results will be lower if the unit is just running from the battery. NOTE: The Advertising references "TX Power:10W/8W/5W adjustable". The results I got did not support this advertising claim. The User's Manual supplied with the radio states "Transmitting part -- Output Power 5-10W". I should note that rated output power from HT's is often not attained unless the unit is operated from an external source of power. I am not aware of a "battery eliminator" or +12VDC connection for this radio. Also, the User's Manual states "The whole part -- Rated Voltage -- DC7.4V(battery). If the unit is capable of running at e.g. 12VDC, higher output power may be observed. Measurements: VHF (2M Band 144MHz): Code: Low: 31.0 dbm = 1.26 W Med: 34.0 dbm = 2.50 W High: 36.5 dbm = 5.00 W VHF (1.25M Band 220Mhz ): Code: Low: 19.0 dbm = 0.08 W Med: 19.0 dbm = 0.08 W High: 19.0 dbm = 0.08 WThis isn't a typo or a cut and paste error. I got the same low readings regardless of TX Power setting. This essentially means that the DOLCOM GP328 does not transmit on the 220 MHz band. I did not test all frequencies/bands, but the DOLCOM GP328 should not be expected to function as a transmitter outside of the 2M / 144MHz or 0.70M / 440Mhz ham bands. UHF (0.70M Band 440Mhz): Code: Low: 29.5 dbm = 0.89 W Med: 32.0 dbm = 1.58 W High: 34.5 dbm = 2.82 W |
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8 | Linuxslate.com Reviews & Commentary / Review Discussions / Mini Review DOLCOM GP328 PLUS and discussion on: Apr 15th, 2023, 4:40pm |
Started by Administrator | Post by Administrator | |
Mini Review and Discussion thread for the Dolcom GP328 PLUS - Another low-priced Ham Radio HT (Handheld Transceiver - Walkie-Talkie) DOLCOM GP328 PLUS ![]() Has this (cheap) old Cynic finally found the Chinese Radio that fits his needs? I'll update this later, but for now, here's a quick list of Pros and Cons: Pros:
Cons:
Please check back soon. I will update this post with actual power output measurements, and other info about this radio. If you would like to ask a question or if you have this radio, please register email "john" at this domain. This domain is "linuxslate.com". I will manually create an account for you. |
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9 | Original Projects and Builds / Other Builds and Projects / Re: Poor Man's version of the Monster GO DJ on: Apr 10th, 2023, 3:01pm |
Started by Administrator | Post by Administrator | |
So I keep learning about other similar products. In addition to the 2 Technical Pro Products described here, I have discovered a number of others. What I will describe here are all similar in at least the basic form factor. They are rack mountable Dual MP3 players/mixers. As far as I know of this writing, they all fit in a 3U rack space, but are also designed to be operated just laying flat on a table. They are likely intended as a "drop-in replacement" for the control head of older Dual CD Players, but of course not needing the separate (also rack mount) Dual CD Player (Drives). It's not my intention to single out a particular product, but I am going to use the PYLE-PRO PDJ480UM as most typical of these products. It is pictured here: ![]() PYLE-PRO PDJ480UM Photo from Pyle Website PYLE-PRO PDJ480UM The same product (although unbranded) seems to be available from Chinese manufactures/vendors listed simply as "DJ Controller, Supports USB and SD Card Player". I have also seen what appears to be the same product branded as the "UC3". Numark DDS This one appears slightly more elegant than the other products mentioned here. It has a single Color display in the center. Pyle-Pro PDJ450U Pro DJ Media Player Controller Another Pyle branded product, and like the Numark DDS, it has a single screen in the center. The same product seems to be sold as the T&W International Audio Co.,Ltd SDJ-1000US as well as possibly other identities via various Chinese Vendors. The next several products seem to be the same device with different cosmetics and branding: American Audio SDJ2 JB USB 900 (JBSystems) Citronic MPSD-2 OMNITRONIC MMP-1 SD/USB UD999 (Unbranded) The UD966 (Also Unbranded) seems similar. Another one is the American Audio SDJ1 / SKP Pro Audio USD-2010 / DJ Tech S1. The same device may also appear with additional names/branding. Note that these devices are just dual players with separate outputs. They do not have mixers, faders, tone controls or Mic inputs. I am leaving them on this list because they are similar devices. Note that this list only contains self-contained units that do not include or attach to CD players. Many Dual CD players/controllers will play MP3 files burned on to a CD. This list would be much longer if I added those. (Note reference to my Numark Mix Deck Express referenced earlier in this thread. I also have a Gemini Dual CD player with remote head.) It is very possible that all of the devices listed on this page are obsolete, although some seem to be available. Note that none of these devices seem to have nearly the sophistication of the Go DJ / Go DJ Plus, such as the spinning record animation or waveform displays. None of these devices are portable/battery powered. Note also that newer, high end devices, such as the Denon DJ Prime Go are not on this list. I consider them to be in "Their own class" (and I'm sure Denon would not want the DJ Prime Go on a list with $150 obsolete products). The Denon DJ Prime Go was mentioned early in the thread. If you have any additional information about the devices mentioned here, or other similar Dual USB/SD players, please email "John" at this domain, and request registration. |
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10 | Original Projects and Builds / Other Builds and Projects / Re: Malachite DSP - SDR Radio Receiver on: Apr 6th, 2023, 10:00am |
Started by Administrator | Post by Administrator | |
New Firmware and other updates to my Malachite DSP - SDR Radio Receiver Contents: 1. Firmware FW_1_10d.d 2. Battery Issues FW_1_10d.d As mentioned previously, It seems Firmware Development for this radio has slowed or stopped. If one follows the links provided in previous posts, and clicks on the "Прошивки(FIRMWARE)", one will end up getting only a text file. This text file contains a link to a Google Drive location, and in that location, one will find a file "Malahit_FW_1_10d.rar" (Not FW_1_10c) and an update Change Log. Inside the RAR file is only the file Malahit_FW_1_10d.hex. Being the brave soul that I am -- and willing to risk my radio for all users everywhere, I downloaded and installed this Malahit_FW_1_10d. What did I do specifically? (Detailed instructions) -- Assumes Linux, but should be similar on other platforms:
I'll post comments on this latest (last?) firmware after I have had more time with it. Battery Issues I had another problem with my Malachite DSP - SDR Radio Receiver. These radios drain the battery over time unless the radio has a hardware battery disconnect switch. The drain is much worse on the "Test" or Unregistered firmwares, but it is present on all FW versions. Over time, this will drain the battery, and there is no low voltage cut-off. Draining a Lithium Ion/Lithium Polymer battery below ~3.3VDC is very bad for the battery, and possibly dangerous. I noticed that my Malachite DSP - SDR Radio was not holding a charge very well at all. I opened the case, and was amazed to find a VERY puffed battery. There is also the possibility that these radios (at least the Chinese clones) are over charging the batteries or charging them at too high a rate. I replaced the battery (4000mah) with a 8000mah battery. Note that at a given charge rate specification (e.g. "1C"), an 8000mah battery can be charged at twice the current of a 4000mah. So in general, a lager capacity battery is going to be more tolerant of "hard" charging than a smaller battery. Suggestions:
I would also like to note that a very similar battery arrangement in My "Poor Man's Go DJ" has not puffed at all despite being subject to a much higher load, and much more frequent use. This is what leads me to believe that the Malachite DSP - SDR Radio is charging the battery in a way that is not good for it. |
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