Re: LDG AT-11MP : Replacement Meter Backlight Bulb
Sorry, guys.? Thought I was
downloading only the last two pages, not the whole document
(twice)!
My bad.
Kent
K9ZTV
On 4/14/2024 10:15 AM, G8JCF via
groups.io wrote:
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[Edited Message Follows]
Thank You MA, unfortunately that link is for the AT-11 which does
not have a meter unlike the AT-11MP, see attachment.
I do have the assembly manual for the AT-11MP, but that doesn't
have a parts list. I also have the schematic for the AT-11MP, but
that just says FWD and REV, see attachment.
Thank You
Peter - GM8JCF
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
I have the parts list which lists only
"meter."? Does not list a lamp.
SEE ATTACHED.
My suggestion is to either replace the LED or see if you can find
a replacement cross-needle meter with lamp attached.
73,
Kent
K9ZTV
On 4/14/2024 10:15 AM, G8JCF via
groups.io wrote:
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[Edited Message Follows]
Thank You MA, unfortunately that link is for the AT-11 which does
not have a meter unlike the AT-11MP, see attachment.
I do have the assembly manual for the AT-11MP, but that doesn't
have a parts list. I also have the schematic for the AT-11MP, but
that just says FWD and REV, see attachment.
Thank You
Peter - GM8JCF
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
Hi JD
I've replaced dial bulbs with white LEDs on a number of my older receivers, but that was fairly easy because the bulbs were quite large in comparison to the tiny little bulb inside the cross-needle meter, and so just using a white LED (3000K) with a series resistor, or in many cases buying an LED with an integrated resistor for 12V, 9V, or 6V was a simple fix, ie just "attach" the LED to the original bulb holder and solder the tails. Because of the way the tiny little bulb is fitted right inside the meter housing of the AT-11MP, I had hoped that I could find a 1:1 replacement, rather than doing a "DIY" fix, but it may be that the only solution is "DIY" fix :-)
Thanks everyone for the ideas & tips
Peter - GM8JCF
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
Yes indeed Ricke, that's probably what I am going to have to do unfortunately.
73
Peter - GM8JCF
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
Thank You MA, unfortunately that link is for the AT-11 which does not have a meter unlike the AT-11MP, see attachment.
I do have the assembly manual for the AT-11MP, but that doesn't have a parts list. I also have the schematic for the AT-11MP, but that just says FWD and REV, see attachment.
Thank You
Peter - GM8JCF
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
LEDs are a great fix. You need to know the voltage, AC or DC and voltage and select a proper resistor.
Also choose the color you want.
I have replaced the dial lamps in a fair number of radios with LEDs because they are often easier to obtain than filament bulbs and you can make them work with different voltages as well.?
Also if you look up or measure the voltage you can often find bulbs that are "close enough" on ebay, but also often from China so a wait is involved.
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
Another option is use a LED with a current limiting resistor appropriate for the voltage. A drop of hot glue or silicone sealant holds it in place yet allows future removal if needed. This assumes it is being fed with DC. I have been doing this on all my modern equipment as needed and I use a blue LED which looks nice, They also make white/clear LEDs
Ricke
AJ8V
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
The assembly manual has a schematic in the back with the parts list that may or may not be of help.
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
Thank you, it looks like A above, I'll see if I can get these parts over here
Thank You
Peter - GM8JCF
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Re: LDG AT-11MP : Replacement Meter Backlight Bulb
It looks a lot like the meters MFJ uses. Might be the same bulbs. Take a look at these. This is from page 85 of their current catalog. 
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LDG AT-11MP : Replacement Meter Backlight Bulb
Hi
After years of faithful service my LDG AT-11MP Backlight Meter Bulb has failed - I contacted LDG to ask if they knew of the part number for a replacement bulb, but unfortunately they couldn't help.? So I'm turning to the wisdom of the group that someone here can point me in the right direction, and very preferably (crossed fingers for luck) if there is an LED equivalent.
I've had a look at the meter bulb and it looks like a T5 286, but don't have a T5 286 to hand to actually compare physically unfortunately.
Thanks in advance
Peter - GM8JCF
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Re: RU-1:1 UNUN SWR behavior, Is this normal?
Addendum to my last post:
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Because I don't own an LDG RU-1-1 myself, I have so far only commented on the chosen design.
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The implementation shown in the photo shows at first glance 2 points which can have an unfavorable effect on the insertion VSWR.
These are, on the one hand, the long connecting wires on one side and the significant spread of the bifilar transmission line.
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Anyone interested in this topic could definitely find some suggestions for balun design and implementation in Owen Duffy's many publications, such as this one:
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?
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Re: RU-1:1 UNUN SWR behavior, Is this normal?
I don’t follow that logic nor do I believe that claim.? And I’ve never seen a situation needing such a crazy dual 50ohm feeder … I don’t ever recall any conversation of a 100-150 impedance ratio with a 1:1 choke. ?1:1 obviously means 50 ohms in and 50 ohms out! I’ve built lots of 1:1 chokes. I’ve never had one that was 2:1 at the top of tge 10m band.? Plus I think that choke looks more like amateur construction and is leaning into sloppy or questionable work.?
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Re: RU-1:1 UNUN SWR behavior, Is this normal?
I finally found a photo of this LDG-RU-1-1 on the web.
?
The transmission line design with bifilar wound wires is usually chosen for use on antennas with random and sometimes very high impedances (-> high voltages).
The impedance of such a transmission line is in the range of around 100-150 ohms, depending on the distance between the 2 bifilar wires, which is why a low insertion VSWR cannot be achieved with this design.
Baluns with this design are sometimes referred to as “tuner baluns” because the antenna tuner adjusts for the less-than-optimal insertion VSWR.
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A significant improvement can only be achieved by connecting 2 bisectionally attached bifilar transmission lines in parallel, because this halves the impedance (-> slightly more expensive products).
?
The question asked "Is this SWR behavior typical?" can therefore be clearly answered with YES.
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73, Heinz HB9BCB
?
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Re: RU-1:1 UNUN SWR behavior, Is this normal?
Doesnt ferrite mix mear some? weight in rolloff?
On Wednesday, April 10, 2024 at 10:51:49 PM EDT, Heinz Baertschi <heinz.baertschi@...> wrote:
"Normal" properties of a 1:1 Guanella Balun should be something like this...
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73, Heinz HB9BCB  
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Re: RU-1:1 UNUN SWR behavior, Is this normal?
"Normal" properties of a 1:1 Guanella Balun should be something like this...
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73, Heinz HB9BCB  
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Good evening sir……
Well, I do not usually wear the Pedestrian Mobile rig in parks.? I’m a retired and semi-disabled combat vet.? Army Doc warned me…. No more running or I’d need new knees…. But walking and bicycling were great.? I am 68 now.? So I built that backpack radio.? The antenna design work was most amusing.? It has a center-loaded tunable vertical whip about 10-ft tall.? None of this was done by calculation, it was all empirical testing on the air.
If you understand antenna resonance as when R=? but X=0, then start from there you quickly discover that body capacitance to the pack frame react to the antenna tuning and you need about 15% more length to off-set the capacitance.? The initial antenna length was set by using a Hustler MO-3 mobile mast with a telescoping whip on top.? This combination was set to resonate at 50.200 MHz.?
If you have ever experimented with coil-loaded vertical antennas, you know that coil placement can be crucial for both efficiency and ease of tuning, and those parameters are mutually exclusive.? My desire was to reach 6m to 60m.? My antenna coil of choice was the Wolf River Silver Bullet 1000 Platinum.? Yeah, it was a little pricy.? But it also looked like the most efficient available.? With the idea of making 60m and using the whip top that made 6m possible, the position of the antenna coil had to be low enough to resonate all the way down to 5.200 MHz, but no lower to preserve best efficiency.? Fortunately, I’m pretty good with hand tools and I was able to measure the lowest resonance with the full MO-3, make some back of the paper-napkin calcs, trim the mast and rethread it with a 3/8-24 Heli-coil.? I deliberately under-cut it and retested it, found my calcs close and cut it to perfection the second time.? So the mast and upper whip without the coil works 6m.? Add the coil (about 15 inches) and the upper whip, and about 2 turns of coil for 10m.? Continue to add more turns for 12m-15m-20m-30m-40m, and 60m requires nearly the whole coil in line.
One special note….. I drag a wire on the ground behind me as a counterpoise.? The vertical whip needs to be about 15% longer to resonate.? The drag-wire needs to be about 15% shorter to resonate.? Don’t ask me to explain that one, I’m not that smart.? But that is how it turned out.
I also operate 2m and 70cm, but that takes a completely different antenna.? I walk at lease 3 miles in an hour, some of the local nets are 2m-SSB. 6m-SSB and 10m-SSB.? So three nights a week.? One day a week I try to get out along the Rio Grande, 8 to 12 miles.? And the wife has me going to the gym with her 4 days a week.?
As a proof of concept foe the backpack rig, I entered the 2017 Field Day as a 1C-WTX, QRP CW.? I walked about 25 miles for Field Day, operated 18 hours total.? I got 20 MPG.? That’s right…… I walked 25 miles and I drank 5 quarts is Iced-tea.? Unlike a vehicle, I was putting a small amount into the tank (ice-tea, not gas) as I walked, but I had to hold the “exhaust” to the end of each 5-mile loop when I passed home.? ?? But the real shocker was when the results were published!? Have a look.? Yup, I was the #5 mobile in the USA.? Walking-mobile.? ?QRP-CW was the key.? Each contact was worth a bunch of points.? Each 100-watt SSB contact is one point.? Each CW contact was 2-points, and the QRP multiplier was 5.? So one contact was 10-points.
NOTE:? Trying to send clean CW while walking on a rough river bank is damned difficult.
I love this radio stuff.? Unlike my shooting and camping, I can still be on the air with my last breath.
EVERYONE-stay safe and well………?? get out and experiment.? Play Radio. ?I never met a dying man who regretted not working more. ? ? Vy73? –? Mike? –? KD5KC – WRFF851 –? El Paso – Texas? –? DM61rt.? SOTA W5T-Texas Association Manager. ? The canyons are calling, colorful and deep.? But I have promises to keep. And miles to go still in my Jeep...?? And miles to go still in my Jeep... ? 
? ADVENTURE:? The respectful pursuit of trouble.?? An EXIT is really an ENTRANCE to someplace new.? It isn’t an ADVENTURE until something goes wrong! ? ?
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From: [email protected] < [email protected]> On Behalf Of Lawrence KC6WOG Sent: Wednesday, April 10, 2024 12:31 PM To: [email protected]Subject: Re: [ldgelectronics] RU-1:1 UnUn ? [Edited Message Follows] On Wed, Apr 10, 2024 at 10:34 AM, Mike Olbrisch wrote: SOTA – POTA – Pedestrian Mobile – Camping, it’s all good.
It seems you're having a lot of fun Mike, which I applaud. That's what it's all about. Love the teardrop trailer!
Last year I decided to re-add QRO to my options, rebuilding the Heath SB-1000 that had been gathering dust in my attic for decades. A few months later, I'm rediscovering the joy of QRP and more importantly, portable operation. With this in mind, I've assembled a few different portable options, ranging from 4 watts to 100 with antennas to match.?
I wonder what people in the parks think when you show up with that impressive rig on your back. If anybody asks, tell them you're there to bust some ghosts!
Cheers es 73.
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On Wed, Apr 10, 2024 at 08:54 AM, <rainer@...> wrote:
What “other thread” did you post this and got an answer? I see the same behavior and would like to see the response to this.
Hello Rainier. I didn't get an answer there, but here is the thread. /g/ldgelectronics/message/1393
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On Wed, Apr 10, 2024 at 10:34 AM, Mike Olbrisch wrote:
SOTA – POTA – Pedestrian Mobile – Camping, it’s all good.
It seems you're having a lot of fun Mike, which I applaud. That's what it's all about. Love the teardrop trailer! Last year I decided to re-add QRO to my options, rebuilding the Heath SB-1000 that had been gathering dust in my attic for decades. A few months later, I'm rediscovering the joy of QRP and more importantly, portable operation. With this in mind, I've assembled a few different portable options, ranging from 4 watts to 100 with antennas to match.? I wonder what people in the parks think when you show up with that impressive rig on your back. If anybody asks, tell them you're there to bust some ghosts! Cheers es 73.
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M.A. Glemser
Bruce Collins
Mike Olbrisch
Larry, KC6WOG