Thanks to all the chasers today, specially Barry N1EU and Richard N4EX for the DX QSOs…made my day.
Story and pics at:
http://m0hdf.blogspot.co.uk/2014/07/mtr-v2-sn-370-sota-dx-activation-debut.html
Vy 73s de Angel M0HDF / EA2ECG
In reply to M0HDF:
Nice to see another MTR on the air!
(Jealous)
Tried listening but nothing heard here except the chasers!
73
Pete
In reply to G4ISJ:
Pete, the conditions were not very good yesterday and you might have been in the skip zone.
By the way, which battery do you use with your MTR? The alcaline 9V batteries seem to go down quickly!! I am tempted to go with a LiPo 12V.
vy 73s
Angel
In reply to M0HDF:
Congrats, Angel, for the successful kit assembly and sota activation.
Best 73 de Guru - EA2IF (AM02IF in these days)
In reply to M0HDF:
Hi Angel,
I’ve been using a 3S 11.1v LiPo with my MTR v2. Fully charged its about 12.6v so I run it down to about 12v using my K3, watching the voltage display on the radio.
73
Roger MW0IDX
In reply to M0HDF:
I recently invested in a 370mAh 3S LiPo for my first edition MTR. I made up a dedicated power lead with a 1N4001 diode in series. This setup has been working well for me, I’m showing 4.5w output with fully charged battery on both 40m & 20m. The battery seems to easily cope with my activations, plenty of energy left at the end. The battery is not much different in size to a PP3/MN1604 9V block.
For longer activations, I have a 1000mAh 2S LiPo which seems to last forever! Again this is quite small in size and I still get a useful 2.4w output from the MTR.
73, Colin
Roger, Colin
Thanks for the comments. I am thinking a 3S LiPo 1000mah is the way to go. It should have plenty of juice - my activations are not that long. I might measure my TX current draw to do some basic calcs, I need to search for a web page I saw on the qrp reflector a while back to do that.
My MTR draws 45mA on RX, - close enough to the typical published value.
I have seen the zippy 3s 1000mah for about £12 inc, delivery.
I also seen the special chargers in amazon, about £25-40. Time to invest in one of them. It should also be able to handle my Li-Ion pack for the HB1B, so I will be able to take the battery outside of the rig and the 9v Battery for my 2m Kenwood TH-22E.
I probably need a bunch of connector adaptors too.
73s
Angel
Ps. Guru - thx fer comments. enjoy Galicia and the seafood, good luck with your night contacts.
In reply to M0HDF:
1000mAh 3S should be ample. Some guys have been running their MTRs at above 12V seemingly with no ill effects. I think the key is to have a very good load. A resonant dipole should meet this requirement. I only ever use dipoles cut for band of use. I think you’d have to be careful with end feds etc.
Maybe the best way to go is to carry a 9V battery with you and use it just for powering the rig whilst adjusting the antenna match. I guess you could also use the ‘tune’ function provided on the 3 band MTRs to reduce stress on the PA. The two band MTRs don’t have a low power tune function.
I use a cheap charger from my local model shop, it will charge 2s and 3s LiPo’s. I think it was £11.
73,
Colin
In reply to M1BUU:
Sorry late getting here after working silly hours!
I use 1000mAh 3S lipos but they’re overkill for most of my activations.
A 2 day trip with 5 summits used less than 1/2 the capacity of one pack.
I’m awaiting a friend putting in an order to HobbyKing to add a couple of these
350mAh 3S for me.
It will reduce my pack weight by 42gms!
73
Pete
In reply to G4ISJ:
Thanks Pete. I put my order on Tuesday night for a charger and a Zippy compact 3S 1000mAh 35-45C. Plenty of juice, probably more than needed by what you say.- 92gr!!
Need now a XT60 connector to build a jumper cable between the battery and MTR.
73
Angel
In reply to M0HDF:
Need now a XT60 connector to build a jumper cable between the battery
and MTR.
I get mine from the www.componentshop.co.uk/
http://www.componentshop.co.uk/leads-and-connectors/connectors/xt60-xt90-connector.html
Pete
In reply to G4ISJ:
Thanks Pete. I put my order on Tuesday night for a charger and a Zippy compact 3S 1000mAh 35-45C. Plenty of juice, probably more than needed by what you say.- 92gr!!
Need now a XT60 connector to build a jumper cable between the battery and MTR.
73
Angel
In reply to M0HDF:
Need now a XT60 connector to build a jumper cable between the battery
and MTR.
I always cut the existing connectors off (one wire at a time!!!) and replace with Powerpoles.
73
Richard G3CWI
By accident, rather than by design, I standardized on Deans connectors.
My 3S 370mAh battery and custom power lead including diode and 1A fuse weighs 54g. My power lead is a bit on the heavy side at 15g but I had the heavy gauge twin wire to hand.
Colin
Thanks for the suggestions. I have here some choice to standardise…
Colin, I understand you use the diode to drop the voltage below 12V and polarity protection. Do you have a part number or spec?
Richard, what sort of capacitor did you use to do the audio gain mod? I got a electrolitic one, not sure it is the right type.
73
Angel
In reply to M0HDF:
10u 16V electrolytic. Google the datasheet LM386 for which way round it goes - can’t recall.
73 Richard
In reply to M0HDF:
Any silicon diode should be fine 1N400x series for example. You should see a drop of around 0.8V when drawing a few hundred milliamps (tx). You probably won’t see much drop in voltage when the battery has no load.
Don’t use a Schottky diode as these have very low forward voltage drop. Schottky diodes work well for reverse supply protection in QRP rigs in normal circumstances, 1N5818 for example.
73, Colin
Colin, How did you fit the diode to the dc supply wire? In line Fuse holder?
Regarding the increase audio gain mod that Richard proposed.
I am in two minds about this. On one hand, I observed on my last activation that the audio was kind of low-ish on 20 and specially 17. On the other hand, I have used it at home and got very loud audio on contests and loud stations. (Hearing blast!)
I have been using my iPhone headphones.
I know that the mtr v2 has a circuit to clip the audio, but the limit seems too high with my headphones.
An inline volume control with the headphones might be necessary.
Another observation, with the attenuator on, you can hardly hear anything. - there seems to be a lot of attenuation.
Any thoughts?
73
Angel