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 Post subject: Another Loop Antenna Crystal Radio
PostPosted: Oct Tue 29, 2019 6:41 pm 
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Location: Bangalore
This one uses a 2m x 2m Loop Antenna.

More at

https://nandustips.blogspot.com/2019/10 ... radio.html

Regards,

Nandu.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Tue 29, 2019 7:26 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: S. Dartmouth MA 02748-1225 USA
2M on a side, 78.74 in. Must have some ceiling height to swing that in ones living room...

Can you post an image of the radio in action?

I just got a replica RCA Concert loop. It is diamond pattern and on a 24" table clears the ceiling by 3". I can't use it on the dining table.

Chas

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Wed 30, 2019 6:21 am 
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Hi Chas,

The floor-standing unit is quite heavy and difficult to move. Luckily it's oriented in the direction of the local station and there's no need to move it! The ceiling is at 10 feet.

The shack is quite small to get a photo of the actual unit.

Here's a representation.

Attachment:
123.jpg
123.jpg [ 60.94 KiB | Viewed 2524 times ]


The counter top made it convenient to sit down and carry out the testing.

Many thanks for your response.

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Nandu.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Wed 30, 2019 8:58 am 
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Location: SoCal, 91387
Chas wrote:
I just got a replica RCA Concert loop. It is diamond pattern and on a 24" table clears the ceiling by 3". I can't use it on the dining table.

Chas

Easy solution there; simply cut the legs off the dining table... :wink:

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Wed 30, 2019 3:46 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Nandu,

Took me a moment to comprehend the drawing (image) of your huge loop. It appears to be wound around the external perimeter of an entertainment cabinet.

Great idea!

I have considered doing that to a door in my home, but like most doors, never in a convenient place such that an operating radio can be nearby...

Are you the same Nandu of the Radio Board? Fascinating, Bangalore, officially known as Bengaluru. Wow, city of 8 million some 900 miles from the Equator, summer all the time?

Must be many AM BC stations within the city. So much RF around, DX, is it difficult?

I'll commit, I will rig the RCA replica loop in a large room. I may place the GE super-radio next to it and see how well it does. Pictures later...

-------------------------------------------------------------------------------------

Fifties, Yes the cutting down of the table legs is a better idea than what I had proposed. Busting a pit in my great room concrete floor and setting up the loop in there. The alternate is cutting a hole in the roof and cover with canvas if it rains.

However, setting it up on the much lower end table and the radio on a sofa table nearby is a more elegant and less costly solution. It saves many bruises on my head from the beating I would get with the cut off table legs from my wife. It is her favorite dining table even though it is Formica topped :roll:

Oh, Show us you stubby legged table................

Chas

WA1JFD

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Wed 30, 2019 6:15 pm 
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Location: Beautiful Downtown Burbank CA
I tried this 7' antenna on my lawn and even with an amplified speaker I never heard a thing.


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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Wed 30, 2019 6:59 pm 
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Location: Bangalore
Hi OM Chas,

Yes, I'm the same 'Nandu' and it was my guess too that you are the same 'Chas'.

I'm glad I was able to convey the picture (pun intended)!

No, it's not summer all the time. It's Summer from February to June, Rain from June to November and Winter from November to February. It's pouring right now.

The lone 612 kHz, 200 kW AM station is predominant in Bangalore and BCB DX is well nigh impossible on a crystal radio.

Hearty congratulations on successfully building an RCA Loop replica!

73,

Nandu.

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Last edited by vu2nan on Oct Thu 31, 2019 5:20 am, edited 3 times in total.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Wed 30, 2019 7:34 pm 
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Mike Toon wrote:
I tried this 7' antenna on my lawn and even with an amplified speaker I never heard a thing.

Hi Mike,

You'll need about 6 turns (132' of wire) for your 7 foot diameter loop.

Regards,

Nandu.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Thu 31, 2019 4:41 am 
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Mike Toon wrote:
I tried this 7' antenna on my lawn and even with an amplified speaker I never heard a thing.

Whatever you use for your loop antanna, that is your "coils" which HAS to resonate with your tuning capacitor at the desired tuned frequency. So if your tuning capacitor its at its minium capacitance (fully open) your loop antenna HAS to resonate at ~1600 kHz which is upper BC band frequency. You just cannot use any random loop antenna and expect it to work at your desired frequency, and that applies whether you use a crystal radio or a 5 tube radio.


Last edited by upsss on Oct Thu 31, 2019 5:53 am, edited 1 time in total.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Thu 31, 2019 4:54 am 
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upsss wrote:
Mike Toon wrote:
I tried this 7' antenna on my lawn and even with an amplified speaker I never heard a thing.

Whatever you use for your loop antanna, that is your "coils" which HAS to resonate with your tuning capacitor at the desired tuned frequency. So if your tuning capacitor its at its maximum capacitance (fully closed) your loop antenna HAS to resonate at ~1600 kHz which is upper BC band frequency. You just cannot use any random loop antenna and expect it to work at your desired frequency, and that applies whether you use a crystal radio or a 5 tube radio.
I suppose you meant '~1600 kHz at minimum capacitance (fully open)' or '~500 kHz at maximum capacitance (fully closed)'!

Regards,

Nandu.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Oct Thu 31, 2019 5:51 am 
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Location: Phoenix AZ
Sorry you are right, ~1600 kHz an minimum capacitance or ~500 kHz and maximum capacitance. I corrected my post.


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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Nov Sat 02, 2019 1:14 am 
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Location: Beautiful Downtown Burbank CA
I forgot to mention, when I gave up on my 7' antenna using the 22' of wire, I wrapped the wire around a cigar box. Once inside I connected the ends to my battery powered amp and received the local station. :shock:


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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Nov Sat 02, 2019 6:25 am 
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Location: SoCal, 91387
Mike Toon wrote:
I forgot to mention, when I gave up on my 7' antenna using the 22' of wire, I wrapped the wire around a cigar box. Once inside I connected the ends to my battery powered amp and received the local station. :shock:

Which station, Mike? I remember in the valley there were two transmitters, KMPC/710 in Van Nuys, and KGIL (now KSUR)/1260 San Fernando. Oh yeah, KBLA/1530 Burbank, and KIEV/870 Glendale, although IDK where there transmitters were located.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Nov Sat 02, 2019 5:54 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Beautiful Downtown Burbank CA
KIEV 870 comes in easily on xtal sets here with minimal ant/gnd.

KBLA was in Burbank in the `50s. I lived 3 blocks up the street and only needed a diode, phones, ant/gnd for blaring music and that's all I thought was needed. The transmitter tower was at the now McCambridge Park.


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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Nov Sat 02, 2019 8:45 pm 
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I got the frequency wrong. Oh well, what's 40 kilocycles one way or the other, lol? Dick Hug "Huggy Boy" used to broadcast on KBLA in the early '60's, from a record shop in East L.A. Went there one evening and could see him in the front window. I bought an oldie 45 while there.

Now I'm an oldie, but 45 has long since come and gone, eh eh.

When we lived in Sherman Oaks, I could pick up KMPC and KGIL with a cats whisker/galena crystal setup, one headphone and a short antenna.

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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Nov Sat 02, 2019 9:00 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Beautiful Downtown Burbank CA
In 1958 KBLA changed frequency to 1500 and moved the tower to the Verdugo Mountains.

We have a member that lives across the street from the KMPC towers and had a heck of a time with the 6BM8 transmitter!


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 Post subject: Re: Another Loop Antenna Crystal Radio
PostPosted: Nov Mon 04, 2019 6:27 am 
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Mike Toon wrote:
I forgot to mention, when I gave up on my 7' antenna using the 22' of wire, I wrapped the wire around a cigar box. Once inside I connected the ends to my battery powered amp and received the local station. :shock:

Hi Mike,

I'm sure you'll receive strong local stations on a crystal radio using a 6 turn 7' loop antenna.

Regards,

Nandu.

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