SW-3B-QRP-CW-TRX

Interesting to see the power falling off steadily with supply voltage, I suppose the usual reason for a cliff-edge sensitivity to voltage is an internal regulator requiring some minimum input voltage. The freq synth would normally require stable dc supply? Either there is no such requirement or the output of the regulator is below 6v. Good design for battery operated gear. Field experience or a local monitor would indicate whether there is any fall in quality of signal, chirp etc as the voltage falls.
73 Andrew VK1DA/VK2UH

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MTR-3B vs. SW-3B seems to be a popular topic. I’ve summarized in the table below the main differences between the two. Each radio has unique features, so the bottom line is that there is no clear winner.

EDIT: Updates based on feedback below.

Model MTR-3B SW-3B
Manufacturer LNR Precision Venus Information Technology
Price 299.99 USD 188 USD
Bands 40/30/20 40/30/20
Size 96x64x25mm 104x71x25mm (+15mm protuding knobs)
Weight 125g 180g
RX/TX current 20/700mA 40/800mA
Control Buttons - no protuding knobs Knobs
RF gain control None Yes
Audio output Fixed to 420mV rms with ALC Adjustable
Clock Yes - on digital display None
Frequency memories 1 starting freq. per band 8 per band
Code memories 3 memories, 63 chars each, allowing CQ SOTA Callsign memory for CQ - no CQ SOTA possible
SSB RX No Yes - cross mode possible
Tuning Via menu By turning off/on and simulating straight key
Keyer speed change Via buttons w/ screen display feedback Via key w/ audible feedback
Code visual feedback Yes - on digital display None
S-Meter No Yes
Supply 6 to 12V 8 to 15V
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Useful comparison. As you correctly say, it depends upon what you want. Both are likely to be very similar in terms of RF performance. Does the MTR has proper AGC?

Nice comparison table.

One correction: the MTR-3B does have frequency memories - you can set the starting frequency for each band, so it technically has 1 memory per band.

The MTR does in fact have ALC. This circuit limits the audio output level to about 420 mV rms.

Thanks,

-Josh

Thanks - I’ve made updates to the table.

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Yes but the price is not the same…

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Are there any experiences with the SW-3B, especially using it for SOTA? For example, is the receiver good (enough)?

Axel, DF1ET

See the previous posts.

Hi Richard,
I mean, what are the experiences when using the SW-3B portable, preferable for SOTA. Especially, is the RX sufficient?

You wrote “It works fine. All these simple radios are pretty similar”. Could you add some details? Maybe something about the receiver, and if you compared it with a certain other rig?

Axel, DF1ET

Hi Axel, all these simple radios are very similar in design so the RX is the pretty much the same as an HB-1B, the MTR radios, the Elecraft KX1 etc. Perfectly adequate for SOTA.

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I’ve had my SW-3B on a number of activations and find the receiver more than adequate. At home, side by side with my Elecraft K-3 the sensitivities are indistinguishable, by ear at least. I don’t think the receiver has sufficient filtering for a crowded contest band, but otherwise nice sounding and the separate RF and AF gain controls are nice.

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Sounds really good. Thank you for your answers!

Axel, DF1ET

I received my new SW-3B a few weeks ago. I haven’t had a chance to test it at a summit. Maybe this weekend…
I was able to make a few test QSOs from my house. Seems like a good fit. Its CW filter seems narrow enough. Maybe better than my FT817 with a 500 Hz filter.
It needs to be tested in the field. But first impressions are very positive.

Juan, EA1AER

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Hi Juan, thank you for sharing your impressions, really valuable for me!

Axel, DF1ET

I take the liberty to request the happy owners of SW-3b’s - Richard mentioned in his video on YT that the power plug is untypical. What is meant by this? Do you know the size and if this is available in Europe at all?

Thank you…

It’s the same size as the FT817 power plug.

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Here they write about the ft817 plug, there are also dimensions given. They say, that the following plug fits to ft817:

https://funkbasis.de/viewtopic.php?t=45396

Click on the link even if it says error page.

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Oh, great! 1.7/4.0 same as in Mountain Toppers.

Thanks Richard and Axel. Now I need to try to convince myself I don’t need this trx…
The resistance keeps being fainter and fainter… :slight_smile:

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You definitely don’t NEED it - but clearly you want it! I like mine. I had an MTR but I hated the user interface: for me the SW-3B was a good compromise. I have an FT-817 and a KX-2 as well as other h/b radios. They are all fun in their own way.

PS: NEED is the word I use when discussing new purchases with my wife.

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Even the manual states 4.0/1.7 mm. reichelt.de (if this helps) has 3 types of this.

Axel

https://www.reichelt.de/hohlstecker-c7488.html?GROUPID=7488&GROUPID=7488&GROUPID=7488&SHOW=1&SID=94Wu8iCawQATUAAEdLY8c614119da0ede828a24f3e762540b350b&&r=1

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