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DMR Radio / DMR use in conflict situations
Last post by DL1DBY - Today at 09:25:47 am
Watching videos about global political conflicts, it seems that DMR radios are widely used by combatants, which is interesting.

In Syria the government forces uses Hytera radios, the Russian armed forces often use Baofeng RD-5R. I guess they use their own repeaters. The insurgents in Idlib province also prefer Hytera, though the government claims that NATO made encrypted communications equipment is also used.

In Venezuela the government forces use Baofeng DM-1801/GD-77, whereas the U.S. sponsored invaders recently preferred Motorola XRP3500, according to Venezuelan government sources.

So DMR radios should also be very useful in SHTF situations, especially in closed user groups with encryption (I have not used encryption so far, as it is illegal for Hams).

Best regards
Dieter
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Digital Modes / A kind of WhatApp for HF
Last post by DL1DBY - Today at 08:36:37 am
As I agree with Gil, that having to haul around a notebook, a digital mode interface, the TRX and lots of battery power is very inconvenient in a SHTF situation, I have found something that could be attractive, if it works properly:

There is an Android app made by a russian ham called "HF Pager" or "КВ пейжер" that allows short messages like text or GPS positions (with WhatsApp like functionality like Goggle Maps support) using only an HF transceiver and a smartphone. According to one YouTube video it seems to be sufficient to hold the TRX microphone to the speaker of the smartphone and the smartphone micro to the TRX speaker, as the transmit tones are in the SSB audio channel range. It should also work on FM and even C4FM. The only downside is that the price of the app is somewhat steep with 10 Euros.

Nonetheless I like to experiment with it.

Here is a video on this topic (please excuse the bad quality and the horrible music in the video, it is not my video):

https://www.youtube.com/watch?v=biAKjvsxUMU&t=780s

Here is another video in which they use a specially made TRX for this app (though it will work with any TRX):

https://www.youtube.com/watch?v=Sji85hL2tuc

The last video is by RA3TLB who BTW has an excellent Youtube channel (I use autotranslate closed captions because my russian is too bad). Apart from Gil's and OH8STN's channels it is one of my favorite Ham Radio related channels.

Best regards
Dieter
3
Quote from: nofake on June 04, 2020, 02:25:51 pmI am looking for the service manual for the Icom ic251E and the wire diagram for the mutek frontend board.

1. Free download here (PDF): https://www.manualslib.com/products/Icom-Ic-251e-3963801.html

2. Check pages 12-19 in this PDF about "ICOM IC-251E + MUTEK BOARD":
https://worldradiohistory.com/UK/Amateur-Radio/Amateur-Radio-1983-07.pdf

I didn't succeed in finding the Mutek circuit diagram for you. I found these phrases at more than one site, probably what you didn't do?:

Quote from: undefined(1) FRONT PANEL

  • Remove four retaining screws and top cover.
  • Remove four retaining screws and bottom cover, disconnecting the speaker.
  • If you have a Mutek front end board fitted remove it now. MAKE NOTE OF THE CONNECTIONS TO IT! ***WRITE IT DOWN***
  • Remove the four front panel frame screws
  • disconnect the wiriing harness and remove the front panel. NOTE WHERE ALL THE PLUGS GO! ***WRITE IT DOWN***
  • Locate the orange wire linking the mode switch and the board behind the power control potentiometer.
  • Desolder it from it's present position on the mode switch and move it to the common side of the switch. That completes the front panel mod.
This example from: http://www.pa7es.nl/All_ICOM_mods.pdf

Put this exact search phrase (with quotation marks) into Google:
"If you have a Mutek front end board fitted remove it now"
Check the hits, even the picture hits, maybe something there will yield what you need. Good luck!
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Hello,

I am looking for the service manual for the Icom ic251E and the wire diagram for the mutek frontend board.
I had a problem with the mutek board and took it out without making pictures or schematic of the wires, and now i have nothing on the recieving end.
Can anyone help me with this problem.

73
ON3TVA
5
New To Radio / Re: Favourite band for Morse (...
Last post by bkmoore - June 03, 2020, 01:06:06 pm
You can't go wrong starting on 40m. Most slow speed CW is between 7.050 and 7.060 or above 7.110 MHz.
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Antennas / Re: Unum for 72 ohm coax
Last post by Nigel - June 03, 2020, 12:25:10 pm
Thanks Gil! Will wind at 9:1 and see how it goes with the SDR and HW8.
Nigel
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Antennas / Re: Unum for 72 ohm coax
Last post by gil - June 03, 2020, 04:17:39 am
Hello,

Given the variations of impedance of random wires, I don't think it would make much of a difference...

Gil.
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New To Radio / Re: Favourite band for Morse (...
Last post by gil - June 03, 2020, 04:16:37 am
Hello,

40m is a great choice, and as your only band, go for it!
I do like 30m but because there are no contests there and no voice ops, and also because I already have a bunch of 40m radios...

Gil.
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New To Radio / Favourite band for Morse (and ...
Last post by captainsemtex - June 02, 2020, 08:51:31 pm
I'm not new to Amateur Radio... but am new to HF. I'm currently learning Morse Code and plan to order the new QRP Labs QCX+ kit and matching 50W PA.

But which band to choose?

My default choice is 40m because I know there are some slow Morse stations there but what would you suggest please?

73 Ian
10
Antennas / Unum for 72 ohm coax
Last post by Nigel - June 02, 2020, 06:04:34 pm
Am I right in assuming that 7 windings instead of 9 would be a better match for a random length end fed wire antenna using a 72 ohm coax feed? E.g. 7:1 instead of 9:1.
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