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 Post subject: Meguro MSG 274-E?
PostPosted: Apr Sat 21, 2012 12:26 am 
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Joined: Feb Sun 20, 2011 3:13 pm
Posts: 84
Location: Sao Paulo, Brazil
Hello!
I've been offered a Meguro RF Signal Generator here in my neck of the woods for $200, since I'm just began crawling in this hobby I would greatly appreciate some input before I decide to pull the trigger. I tried googling, but nothing really came up. Has anybody out there heard of this brand? Would it fit my needs for aligning AA5's? I had a EICO 330 inherited from my dad, but unfortunately it has died.
Thanks!
Ed


Last edited by edumen on Apr Thu 26, 2012 9:37 pm, edited 1 time in total.

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sat 21, 2012 1:32 am 
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Location: Erie, PA
Meguro did make (and still does make) excellent lab quality test equipment. But this signal generator model looks like is was made for some sort of specialty application because as far as I can tell from these pictures on a foreign sales site, it only covers a single bandwidth from 4-7 MHz, which would make it useless/worthless for any practical purposes. If someone knows what the application was, perhaps they can share. Possibly Japanese military or ? Definitely weird. I would not even consider buying it unless you want a big paperweight.

http://produto.mercadolivre.com.br/MLB- ... g-274e-_JM

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sat 21, 2012 1:45 am 
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Joined: Feb Sun 20, 2011 3:13 pm
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Location: Sao Paulo, Brazil
Yes Mark, I have the same doubt! And no, I don't need anymore paper weights around, my old man left plenty of them, I got stuff that I even don't know what it's used for. :roll:

Ed


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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sat 21, 2012 4:54 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
It looks like something that might have been used to service marine coastal radiotelephones about
40 years ago.

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Thu 26, 2012 9:36 pm 
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Joined: Feb Sun 20, 2011 3:13 pm
Posts: 84
Location: Sao Paulo, Brazil
Please, guiding light!
Went to look a different model Meguro today that "might" work for me. Took some pics! It tested good on a frequency counter, but I was unable to see a wave form on my scope. On my dead EICO I was able to see a waveform output. What am I missing? I noticed that it has an output of 1uV at 0dB, is this too low?
Thanks!
Ed

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Thu 26, 2012 9:56 pm 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Your generator is capable of producing 1 microvolt. When it does, you can say :

The level is 0 dB/uV.

If the output was minus 6 dB, then the output voltage would be 1/2 microvolt.

The dB/uv unit is common with radio generators.

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Thu 26, 2012 10:49 pm 
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Joined: Feb Sun 20, 2011 3:13 pm
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Location: Sao Paulo, Brazil
Thanks Steve! I will try and bring someone "who knows" along to test it for me. BTW, will any RF coaxial cable work, or there is a specific one for these type of generators?
Thanks!
Ed


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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Fri 27, 2012 2:21 pm 
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In my ventures I have not come across a signal generator with output calibrated in db/uV. No matter, it is likely that if the counter measured the carrier frequency correctly, the output section is at least working. Either the scope or the SG might have been attenuated too much for the scope to see the output waveform. The 221C would be a an excellent SG for aligning and testing many types of AM radios, it covers 100 kHz to 30 MHz and likely has the stability to allow for work on communications receivers. (In other words, this SG wasn't a toy.) Good idea to bring a buddy along to put it thorough some basic "paces" before buying it. It was made to use standard 50 ohm BNC test equipment cables, there are no fancy cables or probes or anything.

-Mark-

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Fri 27, 2012 5:02 pm 
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Joined: Feb Sun 20, 2011 3:13 pm
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Location: Sao Paulo, Brazil
Thanks for the insight Mark! I just got back from the guy with the SG, my buddy ran a test hooking it up to a radio, we did not get the audio tone, something isn't right. It does register on the frequency counter, but something is up with the output. My buddy took it to try and troubleshoot it with his gear. I will probably know what's up tomorrow, I sure hope he can figure it out, I am willing to buy it if it's fixable, it sure "feels" like a nice piece of equipment!
Ed


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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Fri 27, 2012 5:23 pm 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
I see that you are in Sao Paulo, and I wonder if are acquainted with Carlos Alberto Fazano.
This gentleman has authored articles on Brazilian radio history in AWA Review and OTB and
won the Houck award in 2006.


Years ago he sent we exchanged some collectors items.


It would be nice to know how the collector and restoration community is doing in Brazil these days.


This meter face might help in converting the units. If your generator was putting out 60 dBuV it would
be only 1000 microvolts , or 1 Millivolt.

Attachment:
meterscale dBuv.jpg
meterscale dBuv.jpg [ 88.7 KiB | Viewed 1402 times ]


.

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Fri 27, 2012 6:21 pm 
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Location: Erie, PA
edumen wrote:
Thanks for the insight Mark! I just got back from the guy with the SG, my buddy ran a test hooking it up to a radio, we did not get the audio tone, something isn't right. It does register on the frequency counter, but something is up with the output. My buddy took it to try and troubleshoot it with his gear. I will probably know what's up tomorrow, I sure hope he can figure it out, I am willing to buy it if it's fixable, it sure "feels" like a nice piece of equipment!
Ed


The audio tone will be from the modulation when its set. It looks like the meter will measure the modulation percentage when switched to the "mod" position, and the level is adjusted with the "mod level" knob. If that doesn't work, it has an issue.

-Mark-

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sat 28, 2012 12:38 am 
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Joined: Feb Sun 20, 2011 3:13 pm
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Location: Sao Paulo, Brazil
"see that you are in Sao Paulo, and I wonder if are acquainted with Carlos Alberto Fazano.
This gentleman has authored articles on Brazilian radio history in AWA Review and OTB and
won the Houck award in 2006."
No Steve, I have never heard of Mr.Fazano, but that doesn't mean much, for I am just now starting to get into vintage radio repair. From what I googled, he seems to be really into it, lots of publications from him in this neck of the woods! My buddy that went with me to check out the Meguro is really into to it hardcore! He has hundreds of radio's, many aviation communications sets that he salvaged from "our" FAA comunications stations, he has an amazing collection! Thanks for the meter pic!

Mark, thanks for the run down on the Meguro, I sure hope it's salvageable, I will probably know tomorrow! I really liked it!
Thanks again!

Ed


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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sat 28, 2012 6:19 am 
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Location: Erie, PA
edumen wrote:
Mark, thanks for the run down on the Meguro, I sure hope it's salvageable, I will probably know tomorrow! I really liked it!
Thanks again!

Ed


Meguro test equipment never found a USA distributor so you don't see too much of it here, but I wish there were more of it available on the used market as it seems like it was top notch.

-Mark-

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sat 28, 2012 11:29 pm 
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Joined: Nov Fri 06, 2009 1:04 am
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Location: Rochester, NY 14425
I have a Meguro MAK-657A Audio Distortion Meter that I've never been able to find any specific information on. Built very well and seems to work very well. There is a manual for a MAK-6571B that is getting me by.

Attachment:
meguro.jpg
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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sun 29, 2012 1:17 am 
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Joined: Oct Sun 11, 2009 10:06 am
Posts: 1441
Location: British Columbia
Hello edumen. 1uV is very small and you will need more output to align most radios. Almost all frequency counters will not read at that low level of RF. If 1uV is its maximum output, you will have to make a small RF amplifier for it.


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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sun 29, 2012 4:22 am 
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Joined: Feb Sun 20, 2011 3:13 pm
Posts: 84
Location: Sao Paulo, Brazil
It's fixed! Buying it! :D My buddy nailed it, it was a bad FET transistor. He said it's the best RF generator he's come across, very very stable and the frequency dial is dead on, he also mentioned that the attenuator switches are made of silver. According to the seller, these RF generators (he has 2 more) were bought in auction from the Toshiba assembly plant here in Brazil. The only bad news for me, is that I will only be able to begin playing with it a week from tonight, I'm on my way to NJ for the week!
Thanks everyone!
Ed


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 Post subject: Re: Meguro MSG 274-E?
PostPosted: Apr Sun 29, 2012 6:46 pm 
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Location: Erie, PA
It will put out well over 1 uV, that is put there just to show that the output attenuation is metered in "db referred to 1 uV," a reference common to RF engineering but not so common on signal generators especially those in the USA. You could use a conversion table on the internet to see what the output is in the more common RMS or dBm. Glad to hear it is working again and you are buying it. I was fairly sure a lot of Meguro equipment was used on production lines by Japanese electronics companies so it had to be well made, accurate and stable.

-Mark-

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 Post subject: Re: Meguro MSG 274-E?
PostPosted: May Tue 08, 2012 12:27 am 
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Joined: Feb Sun 20, 2011 3:13 pm
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Location: Sao Paulo, Brazil
Well folks, back at it with the SG generator! I'm trying to figure out how to convert dB output to uV. It's attenuation is in dB, the coarse (B) attenuator goes from 0 to 80dB and the fine (A) 0 to 20dB. If I select 60dB on the coarse and 10dB on the fine, I believe I have 70dB output, right? But how do I transform this output into uV? Anybody??

Ed
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 Post subject: Re: Meguro MSG 274-E?
PostPosted: May Tue 08, 2012 1:57 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 6050
Location: Powell River BC Canada
Yes, add the two dB readings. Then calculate like this :

70 dB uV , 70/10 = 7
antilog 7 = 10,000,000
square root of 10,000,000 = ~3162 uV


Its as simple as income tax :shock:


However your generator says : open circuit voltage



If connected it to a 50 ohm load, the voltage drops 50 %

So the actual dB uV drops 6 dB .

To avoid confusion, and the "6 dB lie" HiFi tuner makers long ago were required to state
specs as dB fW-- (femptowatts) which removes about the signal a tuner was getting.

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Amateur Radio Literacy Club. May we help you read better.
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 Post subject: Re: Meguro MSG 274-E?
PostPosted: May Tue 08, 2012 2:21 am 
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Joined: Feb Sun 20, 2011 3:13 pm
Posts: 84
Location: Sao Paulo, Brazil
Thanks Steve! Digested the first part pretty easy, still having some trouble comprehending the last of it, but will work on it.
What does the Z=50ohm mean?
Say I tuned 550khz with a modulated 400hz AF on my SG, I will hear the 400hz when I tune the radio to 550khz, correct?
But will I hear it, If I tune the radio to 1100khz, since it's a harmonic of 550khz? Am I mixing things up?
Thanks!
Ed


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