What I don’t like about the USB battery + regulator is there are too many things to fail or make RF hash. You have a regulator going from the internal lithium battery to 5V, then another to go from 5V to 12V.
3S LiPo has no regulators. If you want to charge your phone then get a bigger 3S LiPo and wire up an automotive type charger (12V to 5V). If the regulator isn’t RF quiet, you can charge your phone when you aren’t playing radio. If the regulator fails then you can’t charge your phone, but your radio will still work.
When I go on backpacking trips I generally snag some first activations that are not possible as day trips. I’d hate to miss out on those because of a blown regulator!
Thanks for the feedback. How do you make sure that a fully charged 3s Lipo like you are using does not exceed the 12v maximum on the MTR? I know they are rated for 11.1v but I’ve read that fully charged they can peak above 12v. Seems like adding a voltage regulator would cause the same RF noise issues that you pointed out in my current setup (the cable has a Drok voltage step up/down regulator inside it).
Also, I would be curious what kind of runtimes you’ve found with that 800 mah battery? The stripped down nature of a small 450 mAh 3s Lipo system does appeal to me.
I used to just turn my charger off when the battery reached 12V, the battery will still be about 93% full. However, I don’t really worry anymore. I find that the battery drops back to around 12V overniight through self discharge anyway. Just make sure your antenna is a good match.
73 Matt
I don’t worry about it. Fully charged 3S is 12.6V hot off the charger. Hasn’t blown up my MTR yet, and I know a lot of others who have been using 3S with MTR for years with no issues. So long as your SWR is reasonable I don’t believe there is any danger. If you do blow the finals, they can easily be replaced for a couple of dollars… the PA FETs are BS170s.
When they say don’t run on ‘12V’ I think they mean a typical 12V ham radio type power supply, which is usually 13.8V.
As for runtime on the 800mah… summer 2018 I used it on a 7 day backpacking trip that included 6 activations. Each activation was 30-45 mins of actively calling CQ or working chasers. The pack was at something like 11.4V when I got home, so it still had a good amount of capacity remaining.
Bonjour Jo, @F5NFB
N’oubliez pas de mettre votre prénom quand vous postez
La batterie dont vous parlez est livrée avec tous les adaptateurs nécessaires mais le cordon prévu pour alimenter un TX (prises jaunes) fonctionne avec un FT-817nd, un QCX et d’autres sûrement …
Cette batterie est extrêmement costaud mais si vous faites de l’écoute cela ne va pas convenir il faut qu’il y ait une consommation (TX ou autres) sinon elle repasse en mode standby (veille).
Voilà si vous voulez en savoir plus contactez @F4VPX Filipe qui l’utilise couramment (120 QSO de moyenne par activation)
There have been recent discussions elsewhere about the efficiency of the MTR3b:
I wasn’t quite sure where to post this, but here goes. As many already know, I toured Europe for a month and only got back last Friday. I took my MTR3b as it is lightweight and goes in the motorcycle topbox very nicely. Just like last year, I took 4 18650 lithium cells and a buck converter to get the voltage down to under 12V. When I set off, the cells were fully charged and the total pack voltage was 16.4, as you would expect. I just checked today, and after 4 weeks on the road the total pack voltage is now 14.5V. So each cell has lost just 0.48V. Here are all the activations I managed:
I make it 32 activations and 514 QSOs. Unfortunately, the freq up button has got intermittent, so I have written to LNR precision to try and get a part number for a replacement. I have ordered an SW3B to try out and see if I prefer it. However, if I can fix the button issue, I will definitely be holding onto the MTR3b.
73 de OE6FEG
Matt
Hi Matt,
Thanks for sharing, impressive low current draw in your extensive testing!
Very well done.
I guess you didn’t experienced any RF noise while using the buck converter?
I use 3 x 18650 LiIon cells to power my MTR 3B. These cells are about 4 years old and I use them only about 2 or 3 times per year as I more frequently use other rigs and batteries when portable.
What surprises me is that these 18650’s show very little voltage drop even when I store them without any maintenance charge along the years!
My MTR-5B has an intermittent UP button but it hasn’t got serious enough forme to replace the button yet!
I have a 1Hz resolution GPS locked frequency counter now, so I could do with doing an alignment of the MTR-5B whilst it’s stripped down for button replacement. My frequency is annoyingly some 10s of Hz off, caused by using the 10Hz resolution counter I had previously.
Give me a shout if you would like me to put a switch or two in the post.
I have the 2 MTR4BV2’s and 2 SW3B’s (spare radio fetish!!!)
I love both models but if I could only keep one I’d chose the Venus SW3B.
Reason(s)
Much more resistant to stray RFI from my logging device (phone)
RF/AF GAIN or on older collector models GIAN!
Tuning much quicker with knob.
Wider voltage range.
Ports out of sides (my preference)
Much cheaper
The MTR4BV2 does have slightly better filtering and is a awesome transceiver as well. The new model MTR which I am anxious to get might pull the MTR ahead of the SW3B.
I don’t have a KX-2 —-yet (argued by some as the best) but the MTR filter is on par with the 705 or perhaps even better.
I’m taking it out for the first time tomorrow, just with a Turnigy nano-tech 460 mAh battery. The service from DHL was very quick and convenient; no waiting 4 weeks for the radio to get through customs as with the postal service. I will be interested to see how it compares to the MTR3b. Certainly, a tuning knob will be nice. I found the CQ memory a bit small, unless I have misread the instructions.
Hi Colin,
thank you very much, the switches arrived yesterday. 4 was very generous of you, I now have plenty of spares. After much work with the solder sucker, braid and old component leads, I got the switch in and the MTR3b back together. It now works perfectly and I am left with only one problem: which one do I take?
quand vous postez 
