I have read a lot about loops and the formulas for calculating a loop for the lowest band you would like to operate.
I have a situation where I a large area to create a loop and wanted some input about whether I should cut if for 80 meters or go ahead and use the entire space available and go with as much wire as possible. I think I should have space for an 800 ft loop.
So I guess my question is should I put out as much wire as possible or cut the loop for 160m (1005/mhz) and expect the harmonics to be resonate on all the bands?
Lee
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Re: NF of devices used in LZ1AQ Preamp
Thanks Everett. Yes if you need the same footprint as the 2SC5551 use the BFU590QX. My PCB's used the larger BFU590GX. Of course both work exactly the same. Just watch out what package you need.
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Re: NF of devices used in LZ1AQ Preamp
Tom,
You need to clarify that that is BFU590QX..
On Wednesday, October 23, 2024, 10:09 PM, Tom - VE3PSZ <thomas.b.seeger@...> wrote: I found that the BFU590's work well in the LZ1AQ circuit. The bias might need to be tweaked slightly to get the lowest IMD if you live in a local BCB area. But once set they seem work as well as the 2SC5551's. Tom
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Re: NF of devices used in LZ1AQ Preamp
I found that the BFU590's work well in the LZ1AQ circuit. The bias might need to be tweaked slightly to get the lowest IMD if you live in a local BCB area. But once set they seem work as well as the 2SC5551's. Tom
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Printables to mount LZ1AQ loops
I was poking around on Thingverse and found a bunch of printables to help mount loops on the LZ1AQ active antenna box. Some cool stuff here.
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Also found this printable to house the controller board.
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Zack N8FNR?
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Re: NF of devices used in LZ1AQ Preamp
Vce, can be a major problem when the load is a transformer with almost zero resistance, and very little if any resistance in the emitter path to ground.
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Regards,
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Martin
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On Wed, Oct 23, 2024 at 02:40 PM, Fred M wrote:
The only issue is Vce max 12V. This means it is risky to use it in the most popular designs like LZ1AQ.
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Re: NF of devices used in LZ1AQ Preamp
On Mon, Oct 21, 2024 at 01:18 PM, vbifyz wrote:
The only issue is Vce max 12V. This means it is risky to use it in the most popular designs like LZ1AQ. The design should be modified to lower the supply voltage to 5V, the recommended voltage for this transistor.
Hi Mike,
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maybe these Application Notes are helpful:
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regards, Fred
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Re: NF of devices used in LZ1AQ Preamp
Hi John,
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Yes. 2SC3357 is a good device.
I have a reel of RF class.
Please email me your mailing address,? I will give you as you need.
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As Fred said, it is more fragile than the 2SC5551AF and 2N2222.
But as Mike says
I should have tried a lower voltage and see.
I always used at 10V them, ?becuse I have a bunch of 78L10F regulator.
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Another one to look at is the 2SC3355.
I have used several.
found it to be more robust than 2SC3357, probably it dissipates heat more easily.
This is a second source by UTC.
It is priced at 20JPY i.e. $0.13.
There is a web page in Japanese.
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This is a well-known store that has been around since the 1970s.
There is no need to worry about fake.
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73, Hisami 7L4IOU
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I just finished putting together an Improved LZ1AQ Loop amplifier that I am offering in several different configurations. One of them is with coax to offer a complete loop. Also this amp could be used as a replacement for W6LVP loop amplifier.
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If interested please contact me off list for a copy of the info sheet. everettsharp (at) aol com? everettshatp@...
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Everett N4CY
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Re: cardioid loop antenna from Cross Country Wireless
I have a W6LVP on a Yaesu rotator but keep my CC Active HF v4 stationary on a fence post, positioned for lowest noise. I like playing around with diversity using both. Experimenting is half the fun.?
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Re: NF of devices used in LZ1AQ Preamp
The NE46134 / 2SC3357 is an excellent RF-Transistor. These meanwhile obsolete transistors are widely used in the RF Stages of Elecraft radios, as for example in the K3. A very similar but newer transistor which is cheap and still in active production is the BFU590Q (SOT89) oder BFU590G (SOT223). Give'm a try.
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One of the reasons, why the 2SC5551AF besides of its superb noise figure became a legend, is its robust silicon structure. Its maximum Voltage ratings (40 V Ucbo, 30 V Uceo) is closer to a xx2222 than to other newer RF-transistors and makes them very reliable in active antenna applications. The junctions of a bipolar transistor behave like a Zener-Diode, exceeding the max. rated Voltages can irreversibly damage the device.
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regards
Fred
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Re: cardioid loop antenna from Cross Country Wireless
I use an Aziloop located 400ft away from house at the bottom of a field in the clear and it works really well 1-10MHz,
Sharp nulls in loop mode from VLF to HF, but in K9AY mode it is limited by the performance of the size of K9AY.
My one is only 20ft across (diameter) and 15ft high and has up to 30dB groundwave f/b 1-4MHz.
A friend tried one close to his house and other antennas and understandably it did not work well in either s/n or bearing accuracy, a remote Wellbrook was better.
John
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Re: NF of devices used in LZ1AQ Preamp
Thanks Hisami, the 4703 certainly looks promising. It is available over here from LittleDiode, a UK supplier on Ebay, but rather expensive so I will give that one a miss.
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However, I have just found another "old stock" SOT89 transistor available for a reasonable cost (?6.95 for 10) from another UK Ebay Supplier (In-Stock-Components) 2SC3357 which has an even lower published NF so I shall add that to my "test" list.
Again only 12v max but has IC up to 100mA, diss up to 1.2W, and low published NF (1.1dB at 7mA and 1.8dB at 40mA with 10v Vce, at f=1GHz).
Its lowest frequency shown is 200MHz so I guess we will not find out how it performs at HF in the usual amplifier circuits (noting what Fred explained) until tested, but worth a try?
John
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Re: NF of devices used in LZ1AQ Preamp
Hi John
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I have some genuine National Semiconductor 2222A's? I am happy to send you some if you are interested in wanting some reference units.
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Let me know, the postage is on me.
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Craig
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Re: NF of devices used in LZ1AQ Preamp
Hi Mike ,
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Thanks for the advice.
I will take care.
The RSP Duo SDR I own has a 4.7V Bias-T.
It looks just fine.
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73, Hisami 7L4IOU
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Re: NF of devices used in LZ1AQ Preamp
Hi Martin,
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Thank you for pointing this out, I will check it.
According to the store's web, they have a significant inventory.
currently 790 bags, i.e. 3160 pieces.
I will buy some.
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73, Hisami 7L4IOU
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Re: NF of devices used in LZ1AQ Preamp
On Mon, Oct 21, 2024 at 12:46 PM, hisami dejima wrote:
Could they be used for LF-HF loop amp?
Parameters look good. 2.5dB noise figure is good enough for HF.
The only issue is Vce max 12V. This means it is risky to use it in the most popular designs like LZ1AQ. The design should be modified to lower the supply voltage to 5V, the recommended voltage for this transistor. I consider this a plus, because the dissipated power is lower with the same collector current.
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73, Mike AF7KR
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Re: NF of devices used in LZ1AQ Preamp
Hi Hisami,
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It may be worth trying some, but they seem to be listed as being obsolete, and don't appear to be widely available.
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Regards,
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Martin
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Re: cardioid loop antenna from Cross Country Wireless
It's not much different from a Wellbrook and rotator in terms of cost, but it is much more sophisticated, and a lot of thought has gone into it's design.
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I think if you are interested in the LF bands, NDB or MW broadcast DXing, it's probably the best option, especially if you have limited space, or other restrictions.
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Regards,
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Martin
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On Sun, Oct 20, 2024 at 10:05 PM, Dave Martin wrote:
That's a lot of money for an antenna I have to build.?
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Re: NF of devices used in LZ1AQ Preamp
Hi All,
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I was browsing for BJTs at Parts Shop in Akihabara.
There, a nice transistor called 2SC4703-NE46234? is available at a low price.
$0.66 for 4!
Could they be used for LF-HF loop amp?
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Hisami 7L4IOU
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Lee-N2LEE
Everett N4CY
Dominic Dambro