Albrecht AE 2990 multimode CB/HAM handheld

I knew it existed but never met one: a 10m multimode handheld. Meet the Albrecht AE 2990 AFS. The same hardware is sold under other brand names. I will not do a complete review, I will document what I haven't found in my online searches about this radio.

It can be configured to work on CB (multi-country) or 10/12m HAM bands. The procedure is documented online and, unless you want to "lock" the change, no soldering is needed. I configured it on HAM bands. Note that there is no configuration that covers from 24.890 to 29.600 MHz. The widest band can be achieved in mode 3 or 4, but it doesn't cover 12 meters.

Finest tuning is in 500 Hz steps within a 10 kHz "channel", with a RIT that covers about +/- 1 kHz. As outlined by others, there is no indication of RIT "zero", which forces you to guess when you are properly tuned to someone calling CQ in SSB.

The stock antenna is a little more than a dummy load. It will not get you further than a couple of km, let alone a DX. So I quickly assembled a 1/4 wave vertical to have a 20 km QSO with a friend. The external antenna was useful to understand that the full RF gain should be used with the rubber duckie, while you should set it one step below max when using better performers. Using full RF gain with an external antenna in my case brought S5 noise and distorted signals.

SSB transmission. I had read somewhere to reduce mic gain to improve modulation. Unfortunately a lower mic gain also means a lower P.E.P. (output power). Going to full mic gain and speaking very close to the radio increased my signal from S1 to S3.

The DC power socket looks like 4.0x1.7 mm, positive centre, but I find it unreliable. Unfortunately the user manual does not mention the right size.

I think that in order to get the best from this radio you need an external antenna and the help of propagation Gods. With a longer whip antenna it could suffice for HF SOTA purposes with local contacts, if you have enough friends at home that will work you.

UV-3R Plus fading display

I got a second-hand-new Baofeng UV-3R Plus and it shows a problem that has not been documented (or I use the wrong search keywords): the LCD display fades out. The longer it stays still, the more it fades out.

See this example about 10 seconds "in":

Fading display on Baofeng UV-3R Plus

 

Top line displays "RADIO" and bottom line is "108.000". Also the display is reacting slowly to any change at 25°C room temperature.

I am not an expert in LCDs and their hardware drivers so I ask if there could be a fix? Or what is the cause of this effect. Given the planned application of this radio and the long queue of projects I will not try a fix myself, unless I am directed to the right spot.

Friedrichshafen 2025: sadness

The largest(?) European(?) German HAM fair for 2025 is over. As in the past, I have planned to limit my fair time to one day but this year I might have needed more hours. Even though the number of exhibitors was apparently lower, the flea market was full of quality stuff.

I perceived a lower number of visitors: even on Thursday evening downtown there were not so many HAMs to be seen wandering on the lake shore/promenade. In contrast, with fewer people walking around it was easier to get close to each table and study the stuff for sale. Maybe there were even less exhibitors than last year and there was more room to walk around.

I spotted the usual Asian guy buying large tubes in quantity but I haven't tried to speak to him.

I skipped tables with microwave stuff, and there were quite a few. So, what did I bring home?

• A board with 8x IV-6 VFD tubes from the Bulgarian guys (also on eBay)
• A set of plastic screwdrivers for tuning RF circuits
• A small Bosch loudspeaker, because it's nice
• A box of HC-6/U XTALs to play with tubes (I bought 1540 kHz then the whole lot) 
• A couple 12 Vdc to 340 Vac 4 mA booster "black box", meant for driving CFL lamps
  

 and for the heavy stuff ...

• An HP 4270A Capacitance Bridge with Nixies

We would have tried the HP 4270A that night at home but we lacked the AC power cord. We checked around the flat and there were no IEC C13 cables so we just unscrewed top+bottom  covers to have a peek inside. It is al almost all-analog device and the service manual is available online, just in case!

Sega Master System II power supply

I was testing some Sega Master System 2 vintage game consoles with a friend and we couldn't get a signal out of them. I used a portable TV with analog tuning to look for the RF signal and nothing. So we tried a different antenna cable, checked the wallwart output, cross-checked with a C64.... Then we found the original Sega PSU and .... OPS! ... SMS2 uses the "Japanese" polarity with (+) on the outer ring and (-) on the tip.

A cold shiver hit us: had we fried all three consoles? Were they already cooked (probably)? Regardless we tried with the right PSU and the signal was there on UHF channel 36 (about 603 MHz)!!

The good news is that Sega used a polarity reversal trick of some kind, but they forgot to put a "power on" LED. The required voltage is 9V.

Happy retroconsoling!

HF portable June 2025

Last Tuesday I had the chance to spend a couple of hours outside in a location where I could do some portable QRP HF. The setup is my usual FT817, end-fed thrown over a tree branch, homemade tuner and CW paddle.

Many flies joined me on the table and many mosquitoes enjoyed my ankles. I had 3 QSOs on 20m, a local friend, a French station in CW and a Belgian in SSB.

I might want to change the capacitor in the EFHW tuner and use a more robust box since the antenna wire pulls quite hard. Weight is not an issue since this location is 50m from the parking lot.

 

 

DC plug for some Yaesu radios

I am not sure the Internet has already found out, but some Yaesu radios share the same DC plug size. In my case I discovered that I can power/recharge a VX-8E (VX-8R) handheld with the FT-817 DC cable. The polarity is also the same, with +/positive in the inner contact.

If I wanted to make a spare cable equivalent to Yaesu E-DC-6, the plug size is 4.0x1.7 mm and it is easily available from multiple sources.

I have also noticed that the universal laptop power supply I own, with exchangable heads and several output voltages, has a compatible plug. Althought it might not be an RF-friendly power source, it offers a way to recharge the radio battery. Make sure to set the voltage to 12V.

Edit.  You know what? Looks like Yaesu loved that DC barrel size, and it was used also on VXA-210 and VXA-220 aeronautical handhelds. Just look for E-DC-6 and see it yourself how many devices.

Not only that, even the Albrecht AE 2990 10/11/12m all-mode handheld uses the 4.0x1.7 mm barrel connector! Or something very similar not documented, but this one works.

Linux on an Intel DG35EC motherboard

Intel DG35EC was (is?) a PC motherboard for Core2 Duo/Quad processor with embedded support for Serial ATA (SATA), PCI Express, Ethernet and USB while still providing support for 3.5" floppy disk drive, IDE hard disks and PCI. Let's not forget PS/2 keyboard and mouse, parallel port and RS-232 (not exposed on the case).

This is probably the last generation of motherboards to support 3.5" FDD, so it is one of the fastest options for a machine that bridges "both worlds". In my case it sits in a minitower case with enough room to swap disks and expansion cards.

It happily boots from FDD, IDE, SATA, USB, network.

Since the primary use of this machine should be to read old disks I preferred to have a form of Linux, to stay away from viruses and have native support for various partition types. The datasheet states that it supports Microsoft Windows.

I booted it with Ubuntu 24 and, even if the MoBo is from 16 years ago, everything worked just fine. I went ahead with installation on a SATA disk. No boot. I've tried every combination of BIOS settings and no, it just sat with a blinking cursor.

Then I plugged an IDE HDD that had Linux on it. Made it the primary boot option and - boom - it booted. So I tried a fresh install on an IDE disk and ... no boot.

In my the experiments to get it boot Linux I had disabled network boot. This switch even broke the boot process of the pre-installed Win7 SATA. WTH!!.

To boot an Intel DG35EC motherboard on Linux my options are (YMMV):

• live CD or USB
• install on HDD but leave bootloader on FDD, USB or CD 
• install on HDD on another computer and move the disk (not tried with a fresh install)
  

Besides this little quirk, it is a fine machine (give it as much DDR2 memory as you can afford, of course). There is "dd" for Windows too which is enough for imaging floppy disks.

Note. I tried forcing the bootloader either on MBR or UEFI and nothing worked. The BIOS does not mention UEFI but it is probably using something very similar as Linux doesn't fall back to MBR.

Note: I tried the same on a DG33BU motherboard and didn't get further, only slower because of the Celeron processor. Most likely all these DG3x motherboards don't support Linux boot after installation.

PABX Excelltel MK-208 recapped

New look for the MK-208

This was an easy fix, on an easy to rework PCB. I replaced the five largest electrolytic capacitors in the MK-208 PABX, even if three of them were still within spec. This 3€(2025) repair restored a crystal clear analog line so the PABX can go into service. I have also drilled free-hand some holes above the 7805 area to let warm air escape.

Phone to phone works. I am after at least one working fax machine and a computer with modem to host the other end. A 1980's BBS will be last.

Electrolytic capacitors in the power supply circuit.

PABX Excelltel MK-208 recap

The (Excelltel) MK-208 PABX (and alike) is a modern local telephone analog exchange for small offices. "Modern" because it was built after 2010, which is strange since plain old PSTN analog phones were already declining in favor of VoIP. "Small offices" because it features up to 2 incoming lines and 8 internal branches. There is a whole series of these PABX with different combinations of incoming vs branches line, and they all fit in the same case. 

MK-208 boards

Why did I buy such a thing? Because I want to be able to recreate an analog telephone line that can ring those old phones, run a BBS, transport a FAX, all natively without passing through VoIP codecs. This is going to be used in a public interactive exhibition. With 8 branches of the MK-208 there can be up to 4 simultaneous calls.

The PABX has a nice case and its weight might induce you to think it is metallic for heatinking purposes. As it will turn out, it's not.

The PABX powers up and the green status LED blinks. This is normal, whereas you would expect a solid light. I connected two phones, they rang and communicated but the line was extremely noisy. No, not the kind of noise caused by a rusty connector. It was a strong hum. Ouch. The hum/noise increased when I picked up the second phone. Ouch ouch. But there is hope: it might be a problem in the internal power supply, even if a poorly designed product would not the THAT bad (and the Internet would be full of bad reviews, which is not).

Let's look inside. The nice heatsink-shaped case is made of plastic, thick, but plastic. The power supply area is easy to locate, with the transformer and the regulator heatsink in good sight. Needless to say, there are three bulging electrolytic capacitors. This unit is 10 years old, it might have been in service non-stop for 8 years. Probably it gets quite hot as there is no fan and the slots for air cooling are very small (to my under experienced eye).

Close-up on failed capacitors.

I will replace the failed capacitors and those that were subject to too much heat. If this fixes the hum, I will also drill holes in the case right above the power supply area to provide a well needed escape to hot air. In between the two I should measure the temperature inside to confirm that extra holes actually help.

 

Motorola MicroTAC GSM battery pinout (incomplete)

A colleague has given me two Motorola GSM phones, a d460 and an International 8700. According to timestamps on the battery packs, they were used in 1998-2001. 

All three battery packs had no output, of course, but helpful + and - signs mark where energy would enter the mobile phone. This allowed me to use an external power supply and confirm the devices work.

Why not trying to recharge their battery packs? These "MicroTAC" battery packs have connections both on the inner side, to the phone, and on the outer side, to the desk charger. I probed around with the multimeter and found the common ground between front and back.

With nothing to loose I set the power supply to 7.2V and started probing around: soon enough the Li-ion battery pack started taking current. What's even better is that it keeps the charge and powers the mobile phone!

For future reference, here is the incomplete pinout for Motorola MicroTAC SNN batteries:

Motorola MicroTAC battery pinout

The pinout depicted in the picture above should apply to these models:

SNN 4027
SNN 4058
SNN 4102
SNN 4132
SNN 4239
SNN 4259
SNN 4263
SNN 4283
SNN 4310
SNN 4314
SNN 4340
SNN 4346
SNN 4383
SNN 4458
SNN 4467
SNN 4612
SNN 4836

As usual, fiddle with these batteries at your own complete risk, even if you know what you are doing.