Just a quick thank you to everyone and this supportive community for their help. I am now sorted…and broke 
I will post pictures when the bits arrive.
4 Likes
Not at all - we still use Miles, Pints and other sensible measures. My HF antennas are measured in Chains!
My son (who is quite a bit younger than Andy) uses feet and inches and struggles with those funny metric measures (maybe that is why it takes so long to investigate road traffic incidents in the North 
)
1 Like
Andy
Could get worse. I distinctly remember working with a builder’s son when we lived in Ireland. He was brought up on metric - but his much older dad - also a builder - had explained and sometimes used inches. This the lad understood but really could not or would not grasp the complications of the likes of ⅚". and other fractions of an inch.
Working on a job together we compromised sometimes when it suited us - eg. ‘‘That needs to be 3" 4mm long’’- a combination of inches and MM 
-
Datasheet ?? Ha Ha Ha ! We’re talking about Chinese units here - no datasheets accessible to mere mortals.
I have noticed that here in Germany you can get some wood beam dimensions that seem rather strange in their metric values but when you convert them to imperial they make more sense - so “3.5 metres of 6” x 4" beam please" makes absolute sense! My guess is that as these beams are often used to replace ones in old houses that were built using imperial measurements, so they need to be able to provide beams cut to the same dimentions!
HNY everyone - Ed.
Makes sense Ed. Most of our measurements, now of course metric, were direct conversions of our old imperial system.
Most do specify what switcher they use actually. For you, read the item description && read the datasheet.
1 Like
No datasheet for the $3/4 boards on eBay! OK, you could buy one, see what chip it uses and then get the datasheet from the chip manufacturer but whether the board has been built to the suggested design from the manufacturer… My thought is that the ones that have been built to manufacturers specs are often RF quiet while others aren’t.
As far as my experience goes, it’s a lottery whether you get a good one or a bad one. Even between batches components may have been missed off the board to save 1 cent.
But if someone on the web wants to review the buck/boost boards and list the good ones, good luck to then as once published the board design has changed and the old board is often no longer available.
Just checked on the Hobbyking site and I noticed that these batteries were still in stock:
You could connect 2 in series to give you 13.2V nominal. Or 2 in series and 2 parallel to give you more capacity. I also noticed that the 8.4Ah are also still in stock:
73 de OE6FEG
Matt
I know I saw someone using tool batteries with a modified charger to be able to link it to the radio. But I wondered if anyone has tried one of these, as tool batteries are easy to come by.
https://www.ebay.co.uk/itm/14-4V-18V-Li-ion-Battery-Adapter-Wire-Cable-Connect-Output-Tool-For-Makita-Bosch-/363191776394?_trksid=p2349624.m46890.l49292
I use buck converters a lot and certainly have never had anyone complain about noise across the bands. My converters have all used 100KHz as the switching frequency. I had one hooked up to my KX3 and checked it out on the panadapter: the harmonic was very low level, even with the RX antenna right next to the TX antenna. However, this could be different for different radios. I am thinking about buying a Tiny SA to investigate precisely this phenomena.
73 de OE6FEG
Matt
They did have a 2000mAh 2s1p in stock when I looked when this thread started. Two of those would have been where I started and maybe add another pair later on nad that’s what I suggested back at the start. The LiPo ship has sailed and I don’t want to buy more. I have two elderly packs I use still to power transverters etc. or 18650 LiIon cells where I have recovered them from free laptop packs. Judicious harvesting of cells has produced 15 of them at 1800mAh and 2400mAh. Fine for an 817 barefoot or my QCX when it comes.
The 8400mAH pack is 120WH and so you can’t take it on a plane with you. Hey Matt… do you remember when you could fly for SOTA expeditions 
Hi Matt,
When the noise occurs, it’s in your receiver normally, I’ve never heard of the noise getting onto the transmitted signal. I had them where the noise level on 40 & 20m has gone up by 3 S-points or more.
On an earlier homebrew portable HF amplifier, I only switched the boost convertor in when I went to transmit, so that it wasn’t running when I was on receive.
73 Ed.
It can be a real issue. Some radios were very poor for it. I may be wrong but I think the Icom IC910 was troubled badly by PSU noise in the transmitter.
Oh, that’s interesting. Most of the converters I use are very quiet in the RX. I think I read on this forum somewhere, that you can get a harmonic on your TX, even when there is no RX noise. That’s what would be interesting to investigate to my mind. Quiet buck converters are easy enough to come by. I can buy you one in Neuhold (Graz) and post it to you if you want.
73 Matt
Thanks for the offer Matt, But I also have a supply of good units, just I can’t say to someone “order from this website” and expect them to get the same quality. From an actual retailer is something else of course, although at the moment, they are all closed here because of COVID.
In my portable supply I built an LMxxx circuit to reduce the voltage so no chance of noise from that solution - just power converted to heat when the voltage is dropped.
73 Ed.
This is probably twice the capacity you need, but seems to be a bargain.
73
Fraser
1 Like
Great price, but a bit big. Would be good in the car.
I think you’re really taking pot luck with these buck converters. There are just so many different ones available, and they are continually changing. On the other hand, they are very cheap, so no big loss if they are noisy. Best way is to just dive in and hope for the best.
73 de OE6FEG
1 Like
Does anyone have a link to a reliable one in the UK?