Date   
Re: Powering that QCX: DC-DC Converters

Jack Brabham - KZ5A
 

Dave,

The regulator I picked up for this project  was ebay 382557154364, you have to take into account the poor translation into English in the ads... but this one appears to do what I want.  The BMS I'm looking at is ebay 312123044794.  There are a gazillion BMS's on ebay , I could probably find a smaller one.

This project is sort of a "warm-up" for the upcoming QSX.   When I get a QSX I intend to do  a full SOTA build with it.  My new QTH in Capitan. NM is surrounded by several 9000 to 12,000 ft peaks. There are 13 SOTA Summits within 25 km.  A few of these are reachable by Jeep (I'm too old for much mountain hiking) and I want to do some SOTA activations on RTTY and the digital modes.

73 Jack KZ5A










On 3/26/2019 8:18 AM, Dave & Ruth Haring wrote:
Jack, please provide more info about the buck-boost as well as bms... that his my question about using a 12V pack...

Thanks in advance, Dave

On Tue, Mar 26, 2019, 10:06 Jack Brabham - KZ5A <kz5a@...> wrote:
Dave,

I'm taking a slightly different approach to the same problem.    I'm planning on building my QCX 20 in a bigger box with internal batteries. (also audio AGC, a speaker, and an amp to drive it...but that's another story).

I'm using a 3x3 cell li-Ion battery pack with a nominal voltage of ~11 VDC.  This feeds a little 2A Buck-Boost regulator that will (in theory) keep the QCX steady at 16V over a wide range of input voltages.

The battery pack has a BMS (battery management system) module that protects the batteries from over-charge etc.  Both of these modules are in the < $5 category.

This approach allows the radio batteries to charge from the shack 13.8 V at home and also supports a directly connected 12V solar cell.   The BMS will manage the battery charging and the BBR protects the radio so no separate "solar cell controller" is needed.

Basically with the BB regulator feeding the QCX, any source of DC from 6V to 20+V should provide a steady Vcc at what ever voltage desired. 

In looking for these look for "automatic" BB regulators, apparently there are some that don't switch from buck to boost mode on the fly.

I am expecting the little regulator to need some minor output filtering to get rid of RF switching artifacts, so that's  something I'll check into when I get it assembled.

73 Jack KZ5A




On 3/26/2019 6:54 AM, Dave & Ruth Haring wrote:
I want to take my QCX on hikes (day trips or overnighters), and am thinking about batteries and output power. I'd really like to run on 14V, but want to keep costs modest. So I thought about battery packs for portable tools, which sit unused when I'm hiking...

18 and 20V are most common now, but 12V is easy to get. I'm wondering about the use of buck converters to drop from say 18 to 14V. And of course, boost converters to go from 12 to 14V.

Yes, I know it's not much dB or S-unit wise. But... when running low power and probably with a compromise antenna, I'd rather maximize it; not make it worse.

Here are the questions:

1. I see lots of offerings on E-Bay and Amazon. How in the world do you have confidence that the products are reasonable and likely to meet my needs, besides proper V-in, V-out, and amperage? Even if I use something else for a high voltage pack (see #2), this will be important because of the availability of small 12V  batteries...

2. What are some other ways to provide ~14V, hopefully with the theme of re-purposing existing stuff? I can strap on an extra cell or two and make my own NiCd pack, but that makes charging more annoying. Others? Maybe diode drops from an 18V pack should be considered, as it's not much less efficient that way than a buck converter and there isn't the possible switcher noise to contend with.

thanks in advance,

Dave N3AC



Re: How to support coax in inverted-V setup?

geoff M0ORE
 

DON'T use silicon sealer intended for bathroom use that smells of acetic acid. It will corrode the copper very quickly.


On 3/26/2019 3:32 PM, Im Scuba wrote:
Hello Jim,  I realize this is a bit of a dated post,  but wanted to share. I recently built a 'center insulator' for my QCX 40, made from 1.5" OFC and flat end caps, SO239, stainless hardware for the legs of antenna, and a zinc eye bolt in the top. My plans are a flat top low dipole at 7' in the back yard, but wanted the ability to hang it up high for possible portable work. All holes were sealed with silicone, and internals soldered & used heat shrink where applicable. It was a little tough to  get it all together, but for literally 8 dollars in parts, I think it's tough to beat. Some photos below.
Used ring terminals from so239 to stainless as well. And the wire used was some romex scrap. Once everything was test fit properly, PVC cemented it together, let it fully cure 24 hours, then siliconed the joints for a bit more protection. Overkill for me, as I dont plan on leaving the antenna up when not in use. (In theory anyways hihi)

Re: Powering that QCX: DC-DC Converters

Steve in Okinawa
 

Today i made the second field outing with my QCX40, primarily to test a new inverted-L setup before going full SOTA this weekend. After trying several power options, including power tool battery (heavy!) and a buck converter with a nifty V-mA display (unreliable), I'm happy with 4 18650 cells. I get 15.5 volts that the QCX seems to like, putting out nearly 5 watts. They last many hours, and while they do take some time to recharge, the pack is small and light. An inline fuse is the only addition. Incidentally, my QCX seems unusually tolerant of high vswrs. Maybe due to Hans' personal touch.

Re: Balloon breaking previous records U3B-25

HF
 

Hi Dave,
I fully agree with you that the meteorological radiosonde balloons and payloads are a vastly larger contribution to the planet's pollution load than the balloons we're discussing here.  In addition to lodging complaints to NOAA and EC as citizens, hams might be able to contribute to a technical contribution to reduce the problem.  If RDF beacons were added to these balloon payloads and the design were adjusted to somehow keep the balloon material together as shreds rather than fragments, then a maybe sport of sorts could develop in which people search for, find, and retrieve them as an RDF exercise.  I'll think about how I might contact someone who is involved in this aspect of meteorology for a discussion.
Cheers,
Halden VE7UTS

Re: How to support coax in inverted-V setup?

Steve Raas - N2JDQ - FN13DD
 

Hello Jim,  I realize this is a bit of a dated post,  but wanted to share. I recently built a 'center insulator' for my QCX 40, made from 1.5" OFC and flat end caps, SO239, stainless hardware for the legs of antenna, and a zinc eye bolt in the top. My plans are a flat top low dipole at 7' in the back yard, but wanted the ability to hang it up high for possible portable work. All holes were sealed with silicone, and internals soldered & used heat shrink where applicable. It was a little tough to  get it all together, but for literally 8 dollars in parts, I think it's tough to beat. Some photos below.
Used ring terminals from so239 to stainless as well. And the wire used was some romex scrap. Once everything was test fit properly, PVC cemented it together, let it fully cure 24 hours, then siliconed the joints for a bit more protection. Overkill for me, as I dont plan on leaving the antenna up when not in use. (In theory anyways hihi)

Re: Balloon breaking previous records U3B-25

HF
 

Hi Joe,
I also don't wish to impose my personal balance point (I like the way you articulate this) regarding littering on others in this forum.  I appreciate having this discussion about where we personally experience that balance point and what sort of things tend to shift it.  Furthermore, the discussion raises awareness of the issue and may stimulate further thoughtful contributions from other forum members.  It's unfortunate that it triggers anger in some readers, but I think it is a fair topic for this forum as long as we continue to refrain from telling anyone else what to do.
Cheers,
Halden VE7UTS

Re: Balloon breaking previous records U3B-25

HF
 

Hi Dave,
Thanks for the mass data on the tripole vs trap dipole options.  If the 7.5m element had a trap in it, it would get a little shorter for resonance because of the inductance of the LC trap that's below resonance, as you mention.  But that's a very small mass reduction and 0.3 grams is a big mass addition!  If it were to be pursued, one way to tune it would be to set it up on a regular transmitter with a feedline to the SWR meter or antenna analyzer, hung out in the open as high as possible.  Once the trap location and overall length are set, transfer it to the balloon transmitter.  I've done something similar to this when making parasitic elements from wire for a Bird-Yagi-Uda where the wire for the parasitic element is different from the material used for the DE.  I tuned it as a dipole at the approximate height where the BYU would be installed, then added and subtracted 5% from the length to make the director and reflector.
Cheers
Halden VE7UTS

Re: Powering that QCX: DC-DC Converters

Stephen VE6SVJ
 

Most 12V rechargeable batteries are over 13V when fully charged and drop voltage as they discharge... by the time a 12V runs at actual 12V, it is almost empty. In fact, for most of them, 11.7V is empty and you should not go below that or you will damage the battery. So when you talk about 14V batteries, presumably you mean ones which are almost 16V when fully charged an empty around 13.5V ? Considering the influence of ground planes, antenna height and band conditions, I would worry less about battery voltage and just go with common 12V ones... it will be much easier to find chargers and replacements. My SOTA friends recommend LiPo batteries, which I have not tried myself, but it does seem like my SLAB's are heavier and don't last as long as their LiPo's. SOTA guys are probably the best to ask for advice on batteries and working portable, so replacing my SLAB's with LiPo's are high on my Christmas list... and 12V seems to be the standard, give or take a Volt depending on charge level.

73,

Stephen.
VE6SVJ


On Tue, 26 Mar 2019 at 06:54, Dave & Ruth Haring <dcharing@...> wrote:
I want to take my QCX on hikes (day trips or overnighters), and am thinking about batteries and output power. I'd really like to run on 14V, but want to keep costs modest. So I thought about battery packs for portable tools, which sit unused when I'm hiking...

18 and 20V are most common now, but 12V is easy to get. I'm wondering about the use of buck converters to drop from say 18 to 14V. And of course, boost converters to go from 12 to 14V.

Yes, I know it's not much dB or S-unit wise. But... when running low power and probably with a compromise antenna, I'd rather maximize it; not make it worse.

Here are the questions:

1. I see lots of offerings on E-Bay and Amazon. How in the world do you have confidence that the products are reasonable and likely to meet my needs, besides proper V-in, V-out, and amperage? Even if I use something else for a high voltage pack (see #2), this will be important because of the availability of small 12V  batteries...

2. What are some other ways to provide ~14V, hopefully with the theme of re-purposing existing stuff? I can strap on an extra cell or two and make my own NiCd pack, but that makes charging more annoying. Others? Maybe diode drops from an 18V pack should be considered, as it's not much less efficient that way than a buck converter and there isn't the possible switcher noise to contend with.

thanks in advance,

Dave N3AC

Re: Balloon breaking previous records U3B-25

Joe Street
 

Well thank you Halden for your perspective and I'm glad I'm not alone.  I do feel both sides of the issue believe me.  I am as much a technogeek as a lover of our surroundings.  I am not surprised that the discussion turns so quickly to a rationale for what is being done, afterall there has been a rational for most of what we have done before, good and bad in this world.  The idea of simply dividing the size of the balloon into the size of the earth doesn't really wash with me, just ask anyone who has done much climbing about how often they find litter in the high places (and I'm not talking about spent cylinders and gear that spoiled rich people neglect to pack out) and you may be surprised.  The high places seem to rake the atmosphere for whatever is borne aloft. I guess I feel strongly about it because the high country is kind of sacred to me.  Being a glider pilot I have seen all manner of things flying in thermals but never a weather or amateur balloon.  Myself I couldn't come up with any rationale for engaging in this aspect of our hobby but then again I wouldn't throw a message in a bottle into the sea or float a truckload of rubber ducks down a river but my personal balance point between being the information seeker and being the nature lover I can't impose on others.  I only wanted to make a suggestion to consider another perspective.

Best regards
Joe ve3vxo


On Mon, Mar 25, 2019 at 8:23 PM HF via Groups.Io <incorridge=yahoo.com@groups.io> wrote:

Hi Joe and others

I am pleased to read that other hams are concerned, as I am, about the garbage problem to which disposable radio balloons contribute.  Thank you, Joe, for raising the issue.

Yes, it's unlikely that a human will encounter one of 29% the radio balloons that falls on land.  However, that doesn't mean it's not garbage or not bad.  Humans are not the only creatures on this planet who are harmed by humans' garbage.  Furthermore, I do not discount the other 71% of the balloons that become garbage in the ocean either.  Yes, the components of the circuit will decompose in perhaps hundreds of years, but only the exposed metals will decompose within the first few years in the ocean.  The circuit board, ICs, and other components will probably last longer than we will.  The mylar balloon will not decompose rapidly in the ocean.  It will last a long time and would probably kill a creature if ingested.  It will become part of the ocean plastic crisis.  See http://plastic-pollution.org/ for an introduction and links to other articles describing various facets of the crisis.

To me, launching a radio balloon is equivalent to throwing the equivalent amount of garbage into the sea or forest.  Rationalizing it as a tiny amount of garbage relative to the enormity of the global garbage problem doesn't satisfy me.  On the other hand, I am eager to participate in this part of the ham radio hobby once I learn a bit more and Hans introduces the U3B.

When I accidentally lose a piece of garbage to the wind while hiking and am unable to retrieve it, I make a special effort to pick up at least that much trash on my way back.  Similarly, I have considered coupling a personal effort to pick up ocean trash or a donation to https://www.theoceancleanup.com/ or https://oceanconservancy.org/  to a future balloon launch.  Still, I'm not quite comfortable with this either, as it reeks of "emissions trading".

I would welcome further discussion and exploration on how we can continue these high-altitude propagation and metrology experiments while contributing to environmental solutions rather than being part of the problem.

Halden VE7UTS

Re: Powering that QCX: DC-DC Converters

Dave N3AC
 

Jack, please provide more info about the buck-boost as well as bms... that his my question about using a 12V pack...

Thanks in advance, Dave


On Tue, Mar 26, 2019, 10:06 Jack Brabham - KZ5A <kz5a@...> wrote:
Dave,

I'm taking a slightly different approach to the same problem.    I'm planning on building my QCX 20 in a bigger box with internal batteries. (also audio AGC, a speaker, and an amp to drive it...but that's another story).

I'm using a 3x3 cell li-Ion battery pack with a nominal voltage of ~11 VDC.  This feeds a little 2A Buck-Boost regulator that will (in theory) keep the QCX steady at 16V over a wide range of input voltages.

The battery pack has a BMS (battery management system) module that protects the batteries from over-charge etc.  Both of these modules are in the < $5 category.

This approach allows the radio batteries to charge from the shack 13.8 V at home and also supports a directly connected 12V solar cell.   The BMS will manage the battery charging and the BBR protects the radio so no separate "solar cell controller" is needed.

Basically with the BB regulator feeding the QCX, any source of DC from 6V to 20+V should provide a steady Vcc at what ever voltage desired. 

In looking for these look for "automatic" BB regulators, apparently there are some that don't switch from buck to boost mode on the fly.

I am expecting the little regulator to need some minor output filtering to get rid of RF switching artifacts, so that's  something I'll check into when I get it assembled.

73 Jack KZ5A




On 3/26/2019 6:54 AM, Dave & Ruth Haring wrote:
I want to take my QCX on hikes (day trips or overnighters), and am thinking about batteries and output power. I'd really like to run on 14V, but want to keep costs modest. So I thought about battery packs for portable tools, which sit unused when I'm hiking...

18 and 20V are most common now, but 12V is easy to get. I'm wondering about the use of buck converters to drop from say 18 to 14V. And of course, boost converters to go from 12 to 14V.

Yes, I know it's not much dB or S-unit wise. But... when running low power and probably with a compromise antenna, I'd rather maximize it; not make it worse.

Here are the questions:

1. I see lots of offerings on E-Bay and Amazon. How in the world do you have confidence that the products are reasonable and likely to meet my needs, besides proper V-in, V-out, and amperage? Even if I use something else for a high voltage pack (see #2), this will be important because of the availability of small 12V  batteries...

2. What are some other ways to provide ~14V, hopefully with the theme of re-purposing existing stuff? I can strap on an extra cell or two and make my own NiCd pack, but that makes charging more annoying. Others? Maybe diode drops from an 18V pack should be considered, as it's not much less efficient that way than a buck converter and there isn't the possible switcher noise to contend with.

thanks in advance,

Dave N3AC


Re: Balloon breaking previous records U3B-25

ve3smf
 

Citizen Science:  I have enjoyed the discussion and information on the amateur radio balloon experiments that are being conducted.  For the past few days the conversation around the breakfast and supper table has been the amateur radio balloon flights and the data they have been generating.  I am in awe of the dedication and resourcefulness of the amateur radio community and the “Citizen Scientist” approaches that are being used.  The mixture of amateur radio, data telemetry and live time internet access to the data is just what is needed to assist the current and upcoming Citizen Scientists to understand the world around them.  These events use so many of the aspects of the STEM curriculum in Science, Technology, Engineering and Mathematics (STEM). 

Using the STEM approach is the best way to develop and maintain the collaboration between the current and emerging Citizen Scientists.  These projects help to ask many questions, stimulate academic debate and focus on the importance of Citizen Scientist observations and working collaboratively with others to solve problems.  Just imagine if this sort of data on the jet stream had been collected by Citizen Scientists for the last thirty years.  We would now have definitive data on the location and relative speeds of the jet stream.  This would have provided the solid information on the changes in the jet stream and the effects of global climate change. This sort of Citizen Scientist research is amazing, just as the annual bird surveys that have been conducted for decades by volunteers all over the world.  I thank those involved in these projects for their dedication.

Regards

Stuart VE3SMF

Re: Powering that QCX: DC-DC Converters

Jack Brabham - KZ5A
 

Dave,

I'm taking a slightly different approach to the same problem.    I'm planning on building my QCX 20 in a bigger box with internal batteries. (also audio AGC, a speaker, and an amp to drive it...but that's another story).

I'm using a 3x3 cell li-Ion battery pack with a nominal voltage of ~11 VDC.  This feeds a little 2A Buck-Boost regulator that will (in theory) keep the QCX steady at 16V over a wide range of input voltages.

The battery pack has a BMS (battery management system) module that protects the batteries from over-charge etc.  Both of these modules are in the < $5 category.

This approach allows the radio batteries to charge from the shack 13.8 V at home and also supports a directly connected 12V solar cell.   The BMS will manage the battery charging and the BBR protects the radio so no separate "solar cell controller" is needed.

Basically with the BB regulator feeding the QCX, any source of DC from 6V to 20+V should provide a steady Vcc at what ever voltage desired. 

In looking for these look for "automatic" BB regulators, apparently there are some that don't switch from buck to boost mode on the fly.

I am expecting the little regulator to need some minor output filtering to get rid of RF switching artifacts, so that's  something I'll check into when I get it assembled.

73 Jack KZ5A




On 3/26/2019 6:54 AM, Dave & Ruth Haring wrote:
I want to take my QCX on hikes (day trips or overnighters), and am thinking about batteries and output power. I'd really like to run on 14V, but want to keep costs modest. So I thought about battery packs for portable tools, which sit unused when I'm hiking...

18 and 20V are most common now, but 12V is easy to get. I'm wondering about the use of buck converters to drop from say 18 to 14V. And of course, boost converters to go from 12 to 14V.

Yes, I know it's not much dB or S-unit wise. But... when running low power and probably with a compromise antenna, I'd rather maximize it; not make it worse.

Here are the questions:

1. I see lots of offerings on E-Bay and Amazon. How in the world do you have confidence that the products are reasonable and likely to meet my needs, besides proper V-in, V-out, and amperage? Even if I use something else for a high voltage pack (see #2), this will be important because of the availability of small 12V  batteries...

2. What are some other ways to provide ~14V, hopefully with the theme of re-purposing existing stuff? I can strap on an extra cell or two and make my own NiCd pack, but that makes charging more annoying. Others? Maybe diode drops from an 18V pack should be considered, as it's not much less efficient that way than a buck converter and there isn't the possible switcher noise to contend with.

thanks in advance,

Dave N3AC


Re: QCX QSO Party 25th March 2019 #qcx #qrp-dx

N3MNT
 

Attached is a beta of a Custom Contest file for QCX QSO Party for anyone logging in N1MM+ .  Rename the file QCX and add to the custom contest folder of N1MM+.  If the other station is running a QCX insert Y or YES into the QCX field ( last field).  Leave blank if other station not running QCX. If you follow this procedure, the program will score correctly.  Note : I have not found a way to prevent the program from auto filling sent RST so you will need to select the field and edit.  I am trying to get answers from developer, but N1MM+ as a contest logging program and speed is king.  I will post updates here when available.

Re: Ultimate3S third party GPS module with no 1PPS #gps

Bela Mucs <mucsb@...>
 

Even more: would U3S work without 1PPS signal? Only only the freq calibration would fail? 

Re: QCX QSO Party 25th March 2019 #qcx #qrp-dx

G4GIR
 

Hi Don
 
I found the same when looking on 30m, then I checked the rules, Only 80,40 & 20 mtrs are included!
Hi  Hi
 
CU next time with a lot of luck.
 
72
 
Ian G4GIR
 
 
 
 

From: Don
Sent: Tuesday, March 26, 2019 12:19 PM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] QCX QSO Party 25th March 2019 #qcx #qrp-dx
 
Whopping three contacts in first time slot, all with QCX-40 as nothing heard with QCX-30 in any of the three time slots.
Thanks to K1RAQ, K4XL and W1BV, none of whom were QCX as far as I know. 
Not much of a "score", but three times better than last month! (SMILE)
Antennas: Stealth, black, after-dark-only vertical and 33 foot 9:1 Unun wire. (Vertical works far better but antenna restrictions here).
Really impressed with the engineering behind these amazing little radios but even Hans can't make propagation better.
See you next month.
Thanks & 73,
... Don K3RLL (FL)

Ultimate3S third party GPS module with no 1PPS #gps

Bela Mucs <mucsb@...>
 

I would like to use a regular (GT-340 FW) Details Here gps module wiht U3S. 
This module has no 1PPS output and can provide both TTL and RS232 signals. 

Does anyone has an experience with this kind of third party modules? What if I connect to the RS232 pins? Would the ATmega328 survive the -+12V input?

Cheers, Béla

Re: Powering that QCX: DC-DC Converters

jjpurdum
 

I'm building a Morse Code Tutor for my FDIM talk, and I'm using a buck converter so that it can be run off a battery pack or a "cigarette lighter", and I'm expecting input voltages anywhere from 13.8V down to 6V, so I'm using one of those cheap buck converters from eBay:


We put it on a scope and it's pretty noisy, but not important for my use. For yours, it would be. We added a filter to it and that knocked almost all of the noise down to an acceptable level for RF work This one's rated at 2W without heat sink. This one costs about $3 and is from a domestic supplier (eBay #322365871574).

This one looks heftier and is rated at 5A and is pretty cheap at 5 for $10. I don't know how it performs, however.

Also, stay away from BC's that use a Phillips head screw adjustment for the voltage. My experience is that, if you look at it wrong, that screw pops off.

Jack, W8TEE


On Tuesday, March 26, 2019, 8:54:43 AM EDT, Dave & Ruth Haring <dcharing@...> wrote:


I want to take my QCX on hikes (day trips or overnighters), and am thinking about batteries and output power. I'd really like to run on 14V, but want to keep costs modest. So I thought about battery packs for portable tools, which sit unused when I'm hiking...

18 and 20V are most common now, but 12V is easy to get. I'm wondering about the use of buck converters to drop from say 18 to 14V. And of course, boost converters to go from 12 to 14V.

Yes, I know it's not much dB or S-unit wise. But... when running low power and probably with a compromise antenna, I'd rather maximize it; not make it worse.

Here are the questions:

1. I see lots of offerings on E-Bay and Amazon. How in the world do you have confidence that the products are reasonable and likely to meet my needs, besides proper V-in, V-out, and amperage? Even if I use something else for a high voltage pack (see #2), this will be important because of the availability of small 12V  batteries...

2. What are some other ways to provide ~14V, hopefully with the theme of re-purposing existing stuff? I can strap on an extra cell or two and make my own NiCd pack, but that makes charging more annoying. Others? Maybe diode drops from an 18V pack should be considered, as it's not much less efficient that way than a buck converter and there isn't the possible switcher noise to contend with.

thanks in advance,

Dave N3AC

Re: IQ balance trimmer potentiometer issue #alignment

James Daldry W4JED
 

Hi, Alan

Sorry to be a bearer of bad news, but NO 2 pins on R27 are joined. The function of the pot is to raise the level of one input while simultaneously lowering the other, stopping when they are identical. You can't get a null unless the ends of the pot are wired identically. Either there's a solder string on the bottom or maybe a wire clipping trapped under the pot. I suppose it could be a shorted pot, but the odds are awfully small.

73

Jim W4JED

On 3/26/19 4:05 AM, Alan G4ZFQ wrote:

I found that R27 has 0 ohms from pin 1 to 2 and around 300 from pin 2 to 3. I assume this should not be zero ohms
But it should. If you look at the schematic you will see that pins 1 and 2 are joined. The control is used as a variable resistor, not a potentiometer.
As others say remake solder joints even if they look good, check voltages.

73 Alan G4ZFQ

Powering that QCX: DC-DC Converters

Dave N3AC
 

I want to take my QCX on hikes (day trips or overnighters), and am thinking about batteries and output power. I'd really like to run on 14V, but want to keep costs modest. So I thought about battery packs for portable tools, which sit unused when I'm hiking...

18 and 20V are most common now, but 12V is easy to get. I'm wondering about the use of buck converters to drop from say 18 to 14V. And of course, boost converters to go from 12 to 14V.

Yes, I know it's not much dB or S-unit wise. But... when running low power and probably with a compromise antenna, I'd rather maximize it; not make it worse.

Here are the questions:

1. I see lots of offerings on E-Bay and Amazon. How in the world do you have confidence that the products are reasonable and likely to meet my needs, besides proper V-in, V-out, and amperage? Even if I use something else for a high voltage pack (see #2), this will be important because of the availability of small 12V  batteries...

2. What are some other ways to provide ~14V, hopefully with the theme of re-purposing existing stuff? I can strap on an extra cell or two and make my own NiCd pack, but that makes charging more annoying. Others? Maybe diode drops from an 18V pack should be considered, as it's not much less efficient that way than a buck converter and there isn't the possible switcher noise to contend with.

thanks in advance,

Dave N3AC

Re: IQ balance trimmer potentiometer issue #alignment

SkipF, NT1G <skip.flem@...>
 

Looks like a three lead pot to me...


On Tue, Mar 26, 2019, 4:05 AM Alan G4ZFQ <alan4alan@...> wrote:

> I found that R27 has 0 ohms from pin 1 to 2 and around 300
> from pin 2 to 3. I assume this should not be zero ohms

But it should. If you look at the schematic you will see that pins 1 and
2 are joined. The control is used as a variable resistor, not a
potentiometer.
As others say remake solder joints even if they look good, check voltages.

73 Alan G4ZFQ