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Re: Consolidated Murania Mods

Rich ¥Weeds¥ Nagel
 

Hi folks, first post here in the forums. I stumbled on a schematic of the modifications to the Murania AM radio elsewhere on the internet, and dressed it up a bit... I figured that I'd post it here :) Also, the last one is a simple idea that I thought of, a switch to enable/disable the R3 modification.

Re: Consolidated Murania Mods

ohwenzelph
 

Update re tuning with 52 turns, 880 comes in when the dial is on 9, so it is probably not yet ideal and might need a couple or a few more turns to be spot on.
(I get pretty much just one local station at 1400 during the day but many many more at night)

Re: Louder??

ohwenzelph
 

fwiw
I have tried a variety of small speakers, 4 8 16 25 32 and 45 ohms, the impedance does not have a noticeable significant effect to my surprise, larger ones seem to make more sound than smaller ones, among those that would fit I have not found one that sounds better or noticeably louder than the ones that come with the kit. A couple that were too large to fit seemed to sound a bit better, and the very largest of my small speakers sounded a bit louder.
 
Having done the mods, my volume control seems to work: nothing at all for affair amount, then rapidly goes to max volume and then no further increase the rest of the way.

73s

Re: Louder??

ohwenzelph
 

Does the volume vary with the speaker impedance? The ones in the photo section seem to be 8 ohms, mine is 16 ohms. Would 4, 8, or 16 be best? Or does it matter?

Re: Louder??

ohwenzelph
 

Hi Matt,
You do have to mess with that little loop of wire “L2”, just in case you haven’t. 
It might make a significant difference if you get it just right.
fwiw
jer aa1of

Re: Consolidated Murania Mods

ohwenzelph
 

Using the wire that comes with the kit I reduced mine to 52 turns and the dial seems to be accurate, at least at with the local 1400 kHz station. Fwiw my AADE meter measured ~210uH. 

I changed Q1 to a BC550C and it works ok, the “beta” on my transistor tester was 483 for the BC550C and 212 for the 2N3904. It might have been a little bit louder but it was certainly not striking (the body of the BC550 has to be turned 180 degrees to get the leads right).

Jer aa1of

Re: Consolidated Murania Mods

AndyH
 

Assembly's not yet complete but wanted to share some numbers from the coil wind.  I decided to include the coil mod/C8 delete from the start.  The inexpensive M4070 LCR meter's been reasonably accurate in the past.  I went with 54 turns.  The following is from the Creamsicle...er...M4070:

62T: 243 µH
57T: 213 µH
55T: 209 µH
54T: 202 µH
53T: 194 µH

72/73, Andy, KG5RKP

Re: Louder??

ohwenzelph
 

After some reflection, it has occurred to me that when building a radio with my grandson, it may well be that limited volume may well be a positive feature for his mother, my daughter...!

Re: Louder??

Curt M.
 

I’m not skilled enough at the component level to find the solution but I have to believe that someone on here will have the answer. As it was mentioned above, the mods made a very big difference in clarity and selectivity but I think the missing part of the kit is the volume. It’s funny because when I showed a few people in my radio club they all say, “turn it up some”. I tell them that as loud as it goes. Then they say, “if it was louder I’d really like to build one of those”. Too bad we all found this out after building it.  It’s such a cool looking radio but just falls short in the volume department. 

Curt M.

Re: Louder??

matthew cook
 

I too would like to see better audio out of mine. Holding it up to the side of my head to hear it is the only reason it sits on my shelf unused..

Re: Louder??

ohwenzelph
 

Is there a better choice for Q1?

Re: Louder??

ohwenzelph
 

I think that after the mods the performance clarity and selectivity seemed better but the volume a bit less and have wondered the same thing.

Re: Louder??

Dave Benson
 

Curt-

Anytime there's a boatload of audio gain, there's always the possible of feedback causing a squeal or motorboating.    Often with an add-on amplifier, it may be necessary to run that on a separate supply.  This doesn't have to be a second battery, though.  If there's enough supply voltage available, a low-dropout voltage regulator may work wonders for isolating the two blocks of circuitry. It can be installed to feed either the outboard amplifier or better yet, the Murania circuitry itself.

73- Dave, K1SWL


On Wed, Feb 5, 2020 at 11:00 AM Curt M. <WU3URADIO@...> wrote:
Has anyone made any modifications to make the audio louder?  I'm not smart enough to do it but it would be interesting if someone could come up with a small amplifier circuit that could be put between the speaker connections and the speaker to give it more volume.  I tried one of these little eBay 1w amplifier boards but there must have been some issues with coupling between the speaker out and the input pf the amplifier board because I just got sort of a squeal.  There's probably some type of impedance matching or attenuation that needs done to make something like that work becuase it didn't work for me.  My hearing is not the best but I was kind of expecting the volume of this kit top be nearly on par with a typical transistor radio.

I know doing something like this would not be good for battery life but I'd really love to set this on my kitchen counter or desk and be able to hear it 4 or 5' away.  I have to have my ear about a foot away or closer to make use of the radio.  I love the look of this radio and it was a fun kit to build.  I did all of the suggested mods but I think it falls short when it comes to output volume.  I probably wouldn't have built it had I known the audio output was so low and yes, part pf that has to do with my hearing but I have a bunch of small radios that's I have no problem hearing that run off of (2) AA batteries or (1) 9V battery.  There must be someone on the board that can resolve this with some type of eBay add on board and a few components?

Curt M.

Louder??

Curt M.
 

Has anyone made any modifications to make the audio louder?  I'm not smart enough to do it but it would be interesting if someone could come up with a small amplifier circuit that could be put between the speaker connections and the speaker to give it more volume.  I tried one of these little eBay 1w amplifier boards but there must have been some issues with coupling between the speaker out and the input pf the amplifier board because I just got sort of a squeal.  There's probably some type of impedance matching or attenuation that needs done to make something like that work becuase it didn't work for me.  My hearing is not the best but I was kind of expecting the volume of this kit top be nearly on par with a typical transistor radio.

I know doing something like this would not be good for battery life but I'd really love to set this on my kitchen counter or desk and be able to hear it 4 or 5' away.  I have to have my ear about a foot away or closer to make use of the radio.  I love the look of this radio and it was a fun kit to build.  I did all of the suggested mods but I think it falls short when it comes to output volume.  I probably wouldn't have built it had I known the audio output was so low and yes, part pf that has to do with my hearing but I have a bunch of small radios that's I have no problem hearing that run off of (2) AA batteries or (1) 9V battery.  There must be someone on the board that can resolve this with some type of eBay add on board and a few components?

Curt M.

Built a Murania last night...

ohwenzelph
 

My experience:
The directions on trimming the extra variable cap straps could be clearer. On the photos page there are 3 pictures showing the variable cap. The first shows it oriented one way and the other two have it oriented 180 degrees opposite and 5 straps are cut not 4. Seems we are removing the trimmer caps in the process but I am not sure. Initially I followed the first picture and then soldered two of the straps back on again and followed the last two pictures. 
Did wind 61 turns and not install the 47 pF cap C8. When i measured it, I got 279uH. Thinking about removing a turn or two.
Replacing the 1K R2 with 2.7K by itself did not seem to make a striking difference. But when I also added the variable resister mods it was significantly improved. The combination, at least, is well worthwhile and definitely recommended.
 I then tried replacing the TA7642 with the circuit used in the Nouveau75 “NM0S Receiver Mods” and powered that with 9v, but my replacement circuit did not work. May need to rebuild that, picture enclosed.
The inside corners of the interlocking fingers for the case are a little bit rounded and I will probably give them a swipe or two with the corner edge of a file to square them off and get a tighter fit.
Did substitute most of the caps with parts from the junk box that measured closer to the stated value, doubt that made any real difference.
Will look for a more robust 9 volt battery connector, radio shack used to have one as an alternative, and I suspect grandson will destroy the soft one fairly quickly.
73
jerry aa1of

Re: Murania is dead after completing build

K4VOZ
 

I found the problem. The solder point of wire going from R3 to C7 cap was loose but not visible to the naked eye.  Re-soldered that connection and problem solved. Thanks for the help.

Tommy
K4VOZ

Re: Murania is dead after completing build

Jim WB2LHP in MI <jmarco1955@...>
 

Hi Tommy...Wow...There's not much that can go wrong with the circuit...If you don't even have power to the LED, I would start at the battery and check the voltage through R5...That's a good place to start...If you just follow the DC voltage around the circuit you should find the problem pretty quickly...GL Jim WB2LHP

On Tue, Dec 17, 2019 at 3:16 PM K4VOZ via Groups.Io <ferrerpc=yahoo.com@groups.io> wrote:
Hi All,

My Murania radio does not power on anymore, no LED or sound comes up. I finished building the Murania kit and was working fine, I proceeded to do  WB2LHP mods and the radio was even better. Now was time to close the case, but the battery didn't fit in correctly. Found R2 and U1 were installed way too high so I bent both of them enough for the battery to fit. Inserted the battery, closed the case, turned radio on and nothing.. no power!!

Here's what I did to troubleshoot: verified battery was good, verified R2 and U1 were not short, check for voltage at R5 like in the instructions: no voltage, verified for loose connections: all look good.

Any suggestions are welcome. 

Thanks

Tommy
K4VOZ

Murania is dead after completing build

K4VOZ
 

Hi All,

My Murania radio does not power on anymore, no LED or sound comes up. I finished building the Murania kit and was working fine, I proceeded to do  WB2LHP mods and the radio was even better. Now was time to close the case, but the battery didn't fit in correctly. Found R2 and U1 were installed way too high so I bent both of them enough for the battery to fit. Inserted the battery, closed the case, turned radio on and nothing.. no power!!

Here's what I did to troubleshoot: verified battery was good, verified R2 and U1 were not short, check for voltage at R5 like in the instructions: no voltage, verified for loose connections: all look good.

Any suggestions are welcome. 

Thanks

Tommy
K4VOZ

Murania You Tube Video

WA0ITP
 

In case you missed it, here is a link to Dave's excellent Murania You Tube video 

https://www.youtube.com/watch?v=YWMzgEpFDJo&fbclid=IwAR3F6E79kZzw7d4pvLgiUwQ7C6x5-GxCZEDb3u6_KryOrPqKOOCbdvT3KiY

It's short and makes for good Sunday afternoon infotaiment (izzat a word?)
-- 
72 WAØITP
I love this radio stuff.
www.wa0itp.com
www.4sqrp.com

Re: Maurania

Everett Catlin
 

Oh Yes I was happy with the Mods.  They  worked well. The basic Murania did everything I asked it to do without them. I saved
the Mod. parts and put it into My Murania Box for future use. Just keeping mine to original specs. I have no problems with it as is. Only problem was a 4 yr old grand daughter over twist tuning cap and bust it. Replaced it and did not glue screw into spacing shaft. Jim they were good and well thought out mods but I mine worked fine here. Look me up on QRZ if you get a chance. Any more Questions just ask.Have a great day.

ev Catlin N5MZX


On Sunday, September 22, 2019, 2:12:30 PM CDT, Jim WB2LHP in MI <jmarco1955@...> wrote:


Everett. Were you not happy with the mods?



On September 21, 2019, at 3:26 PM, "Everett Catlin via Groups.Io" <everettcatlin@...> wrote:


Hi Dave,
I get WMCP, WKOm ?, Some other local stations. WSM out of Nashville. Listen to OPRY Saturday night. Brings back many memories. I did the mod played with it tnd then took it back to original.

73Everett Catlin N5MZX


On Saturday, September 21, 2019, 12:30:11 PM CDT, Dave Benson <davek1swl@...> wrote:


Everett-

Still looking forward to building mine- too many other irons in the fire.

We have a 5kW AM station about a mile from here.  I figure it'll cover the band during daylight hours.  It's Country music, but it's that 'Top-40 Country' format- which seems to be merging with 'pop'. Slim chance of hearing Dolly there! 

73- Dave, K1SWL

On Sat, Sep 21, 2019 at 8:47 AM Everett Catlin via Groups.Io <everettcatlin=yahoo.com@groups.io> wrote:
I just wanted to say that my Murania is still in daily use.I think I have more enjoyment from this kit than any other kit I have ever built. My local station WMCP is on now and I am listening to Dolly sing. Thanks again to 4SQRP.

73
Everett Catlin N5MZX Columbia, Tn.