Date   

radiowe r-108 vs tecsun pl-310et

mariusz.dorota@gmail.com <mariusz.dorota@...>
 

Hello everyone. I have Tecsun pl-310et and I’m very happy with that. I’ve read some encouraging reviews about radiwow r-108, how does it’s sensitivity compare on fm and am to Tecsun ? Some say that it is better, but how come if ferrite antenna in radiwow is shorter than tecsun ? Also I would like to know if on r-108 can you change preset stations with tuning knob (like in tecsun)


Re: Tecsun PL-757

william yim
 

The Tecsun PL-757 is much elder than the PL-310 or PL-380. I think it come at the time when Kaito KA1101 or Degen DE1101 released. 

在 2020年6月4日週四 06:55,dwight richardson <rdrala77@...> 寫道:

Like the Tecsun PL-910 and 920, there is a pre-loved Tecsun PL-757 listed on eBay.  Not much info out there on this model. I can’t even determine if it’s a ULR or not. Looks like PL -310 size but the photos w/o a scale or battery showing for comparison can be deceiving. $39.99 asking price could indicate something a little larger. So does anyone have experience with a 757?  Was this model even made for US market?  All of the button labels are in Chinese. 
--
Bob Richardson
Tuscaloosa, AL


Tecsun PL-757

dwight richardson
 

Like the Tecsun PL-910 and 920, there is a pre-loved Tecsun PL-757 listed on eBay.  Not much info out there on this model. I can’t even determine if it’s a ULR or not. Looks like PL -310 size but the photos w/o a scale or battery showing for comparison can be deceiving. $39.99 asking price could indicate something a little larger. So does anyone have experience with a 757?  Was this model even made for US market?  All of the button labels are in Chinese. 
--
Bob Richardson
Tuscaloosa, AL


Re: Is Tecsun DR-910 still a turkey?

dwight richardson
 

Thanks Keith. And for what it’s worth (JIC anyone is interested) the 910 has a thumb wheel ala pl-310. The 920 has knob ala pl-380. 
--
Bob Richardson


Re: Is Tecsun DR-910 still a turkey?

keith beesley
 

I used a 910 for several years, now MIA. Mine was very good on MW and SW, not so good on FM if that matters. I took it along on a vacation trip to Idaho, and it was pulling in stations at night from all over the western US and Canada. Of course, it didn't have the tuning accuracy of the all-digital models, but good for the price. 

I never had a 920.

Keith Beesley
Seattle WA USA 

On Wednesday, June 3, 2020, 10:06:48 AM PDT, dwight richardson <rdrala77@...> wrote:


Back 8-9 years there are post about the Tecsun DR-910 being a turkey. They are listed new on eBay @ $19.99 with free shipping.  Have any of you learned radio sages played with these enough to know of  easy adjustments or mods to improve performance on MW?  There is also a DR-920C sited at $23.80?  Both digital analog. I don’ think either is PLL.  So is it worth the effort or would it be wise to pass them up because they are cheap for a reason?  Also, JIC anyone is interested, there is a listing for a pre-owned Tecsun PL-757.  This is the only one I have ever seen listed.  Non-US market?  Any potential in the 757s either. Thanks. 
--
Bob Richardson


Is Tecsun DR-910 still a turkey?

dwight richardson
 

Back 8-9 years there are post about the Tecsun DR-910 being a turkey. They are listed new on eBay @ $19.99 with free shipping.  Have any of you learned radio sages played with these enough to know of  easy adjustments or mods to improve performance on MW?  There is also a DR-920C sited at $23.80?  Both digital analog. I don’ think either is PLL.  So is it worth the effort or would it be wise to pass them up because they are cheap for a reason?  Also, JIC anyone is interested, there is a listing for a pre-owned Tecsun PL-757.  This is the only one I have ever seen listed.  Non-US market?  Any potential in the 757s either. Thanks. 
--
Bob Richardson


Re: [irca] TIS/HAR list

Mike Sanburn
 

Thank you!! ms


From: IRCA@groups.io <IRCA@groups.io> on behalf of Phil Bytheway via groups.io <phil_tekno@...>
Sent: Monday, June 1, 2020 12:08 PM
To: NRC-AM <nrc-am@...>; IRCA List <irca@groups.io>; ultralightdx@groups.io <ultralightdx@groups.io>; IRCA2 <mw-dx@groups.io>
Subject: [irca] TIS/HAR list
 
Folks

I've started the process of updating the TIS/HAR list (will take a month or two).

If you have logged a TIS/HAR station in the last 2 years, please forward the details to me at DXM.EiC@.... Call, date, time and brief details are all I  need.

Thank you,

Phil Bytheway
IRCA's "DX Monitor" Editor-in-Chief
Seattle WA
Drake R-7 / KIWA Loop


TIS/HAR list

Phil Bytheway <phil_tekno@...>
 

Folks

I've started the process of updating the TIS/HAR list (will take a month or two).

If you have logged a TIS/HAR station in the last 2 years, please forward the details to me at DXM.EiC@.... Call, date, time and brief details are all I  need.

Thank you,

Phil Bytheway
IRCA's "DX Monitor" Editor-in-Chief
Seattle WA
Drake R-7 / KIWA Loop


Re: FSL Antenna Tuning Course Video

Max Italy
 

Thanks Gary, your explanation is very clear as always.


Fw: Enjoy the Outdoors with Great Radio Reception!

Mike Sanburn
 

This was in my email yesterday. No endorsement implied, but I'm glad that there are some Ultralights still on the market out there....
Mike Sanburn 


From: C. Crane <enews@...>
Sent: Wednesday, May 27, 2020 3:00 AM
To: MIKESANBURN@... <MIKESANBURN@...>
Subject: Enjoy the Outdoors with Great Radio Reception!
 
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Re: FSL Antenna Tuning Course Video

Gary DeBock
 

On Wed, May 27, 2020 at 07:53 PM, Max Italy wrote:

I noticed that passive coupling of a 20" air loop antenna with capactitor to a DSP radio gives better signal than removing the internal ferrite and wiring it directly. Although the DSP chip has an automatic tuning circuit.

This makes me think that the automatic tuning is not so accurate and it may be the main reason why hard wiring a FSL is not even considered an option?

However I did the test with a cheap radio.

Hi Max,

Actually there have been quite a few FSL's hard wired into DSP-chip Ultralight radios, and some of them work quite well. Most of the attempts have been with the Tecsun PL-380, which seems to tolerate an FSL's powerful RF output as long as a small coil is used (3" or less diameter). 

I've attached a construction file for the hard wired 3 inch FSL Tecsun PL-380, of which about 10 were made by me and other DXers back in 2016. A couple of 2 inch FSL Tecsun PL-380's were also made, one of which I sent to Hiroyuki Okamura in Japan. These hard wired FSL experiments were attempted with the CC Skywave Ultralight, but their Si4735 DSP chips were fried pretty quickly. A PL-380's Si4734 DSP chip was also fried when a larger (5 inch) FSL was hard wired in place of the loopstick. 

The hard wired 3" and 2" FSL Tecsun PL-380's work quite well, but the main drawback is that they require the very rare Russian surplus 100mm x 20mm x 3mm ferrite bars, which haven't been available commercially since 2012. These are the same lightweight ferrite bars used in the 5 inch "Frequent Flyer" FSL antennas, so the demand for these rare ferrite bars is extreme.

73, Gary DeBock (in Puyallup, WA, USA)


Re: FSL Antenna Tuning Course Video

Max Italy
 

I noticed that passive coupling of a 20" air loop antenna with capactitor to a DSP radio gives better signal than removing the internal ferrite and wiring it directly. Although the DSP chip has an automatic tuning circuit.

This makes me think that the automatic tuning is not so accurate and it may be the main reason why hard wiring a FSL is not even considered an option?

However I did the test with a cheap radio. 


Re: FSL Antenna Tuning Course Video

Gary DeBock
 

Thanks Gary. The FSL is very easy to master on radios like the 2010, 803A, 880 etc and similar. The later DSP chip radios like the Skywave etc requires some skill to hear the "peak" as they are quite slow to react to the increase in signal level and can be quite frustrating to those who are used to the older style radios.

Thanks Chris (and Todd),

Todd, prior to our joint Kauai (Hawaii) DXpedition in November I provided Chris with the latest 5 inch "Frequent Flyer" FSL model, but he found it a little tricky to find the gain peaks because of the delayed response of the CC Skywave's DSP chip, which always tries to compensate for any antenna frequency changes. Broadband receivers like the PL-880 and ICF-2010 do not have this quirk, and are much easier to use with a razor-sharp tuning FSL. Despite this a DXer can become pretty skillful at using a CC Skywave with a 5" Frequent Flyer FSL if he practices continuously, and masters the DSP chip quirks.

<<<   Based on all the factors involved, I suggest that building an FSL antenna is much more challenging than operating the finished product.   >>>

Any DXer's first attempt at constructing an FSL will probably be challenging, but once you get used to the quirks they are very simple and straightforward.

<<<   The critical FSL tuning is largely overcome by using a 8:1 reduction drive 384p variable capacitor. The tuning sharpness in the video is similar to my 40 inch PVC box loop. Of course the tuning is even sharper down near the bottom of the MW band, e.g. 531 KHz. But I have never had issues re quickly finding the loop resonant signal peak.   >>>

Actually the tuning sharpness of the latest FSL's (tweaked for the maximum gain) is quite a bit trickier than that of an air core loop, Todd, but with some practice a DXer can adjust to it. On an FSL the sharpest tuning is on the high band, and the low band frequencies (530-600 kHz) tune more broadly (i.e., easier to peak the gain boost).

<<<   I gather your backyard 9 foot air core PVC loop is the benchmark antenna for comparing all your other antennas. Is it possible for say a 7 inch FSL to match the 9 foot PVC loop? The benchmark is daytime stable groundwave. But with all the recent metro stay-at-home resultant consumer electrical noise, the bigger 9 foot loop may only produce more signal and noise. Hence the law of diminishing returns kicks in.   >>>

The signal boost from the 9' air core loop is pretty impressive, but the Monster FSL's (15 inch and larger) can match it in S/N ratio. FSL antennas have a natural tendency toward lower noise reception, so a compact FSL design can usually compete with a much larger air core box loop. The latest model 5 inch "Frequent Flyer" FSL's can usually outperform my 4 foot air core box loop in S/N ratio, primarily because of lower noise reception on the weakest signals. Even the latest "Baby FSL's" can sometimes compete with the 4' air core loop in weak signal reception, especially on the extreme low band frequencies when domestic splatter is an issue.

73, Gary

  

 



 


Re: FSL Antenna Tuning Course Video

Todd
 

Thanks to Steve Ratzlaff for notifying me re the March, 2012 Gary DeBock FSL article. I uploaded the file to the antenna section.

Regards,

Todd

https://ultralightdx.groups.io/g/main/files/5%20Antennas%20and%20Equipment/DeBock%202012%20FSL%20Antenna%20Design%20Optimization.pdf


Re: New Parts for FSL and Air Core PVC Loop Antennas

Chuck
 

On Tue, May 26, 2020 at 03:40 PM, Gary DeBock wrote:
If it were me, and if I was cutting the expensive 1162/46 Litz wire to make an FSL coil, even if the Chinese manufacturer says that their ferrite rods are the same (400) permeability as the ones I used, I would cut the 1162/46 Litz wire a couple of extra turns longer than what I did for my existing (Russian surplus ferrite rods) FSL, to account for differences in manufacturing tolerances and measurements.

Otherwise you would need to splice the Litz wire, if you cut a coil too short (to tune down to 530 kHz). Splicing Litz wire is never recommended, since each individual Litz wire strand is designed to have its own performance potential throughout the entire length of the coil.
Gary,
I'll definitely take your advice and cut the wire long by a few turns for experimentation.
And I'm assuming full turns only -- that partial turn winding (like 27.5) aren't valid.
Best,
Chuck


Re: New Parts for FSL and Air Core PVC Loop Antennas

Gary DeBock
 

<<<   Gary,
That makes sense and I totally understand that disclaimer.
The rods I obtained are rated with a permeability of 400, which I believe is the same as the Russian surplus units.
Unless there is some other characteristic to compare and differentiate them, my hope is the ones I got are electrically identical to yours.
Either way, I'll start with 27 turns and experiment a bit before permanently securing the winding. Thanks!   >>>

Thanks Chuck,

If it were me, and if I was cutting the expensive 1162/46 Litz wire to make an FSL coil, even if the Chinese manufacturer says that their ferrite rods are the same (400) permeability as the ones I used, I would cut the 1162/46 Litz wire a couple of extra turns longer than what I did for my existing (Russian surplus ferrite rods) FSL, to account for differences in manufacturing tolerances and measurements.

Otherwise you would need to splice the Litz wire, if you cut a coil too short (to tune down to 530 kHz). Splicing Litz wire is never recommended, since each individual Litz wire strand is designed to have its own performance potential throughout the entire length of the coil.

73, Gary

 


Re: New Parts for FSL and Air Core PVC Loop Antennas

Chuck
 

On Tue, May 26, 2020 at 02:24 PM, Gary DeBock wrote:
Unfortunately, since my  own FSL was constructed with the Russian surplus ferrite rods ordered from a seller in the Ukraine ("alexer1" on eBay), the coil turn information that I gave you may not apply to a an FSL constructed with Chinese rods. The number of coil turns is related to the permeability of the ferrite rods, and Chinese-made rods typically have significantly different permeability than either Russian surplus or Amidon ferrite rods. So you will probably need to fine tune your own antenna's FSL coil because of the Chinese-made ferrite rods. Sorry! 

If a DXer uses the exact same components that I did for my FSL antenna then he would be able to simply construct it in an
identical way, and probably come away with identical performance.
Gary,
That makes sense and I totally understand that disclaimer.
The rods I obtained are rated with a permeability of 400, which I believe is the same as the Russian surplus units.
Unless there is some other characteristic to compare and differentiate them, my hope is the ones I got are electrically identical to yours.

Either way, I'll start with 27 turns and experiment a bit before permanently securing the winding. Thanks!

Best,
Chuck


Re: New Parts for FSL and Air Core PVC Loop Antennas

Gary DeBock
 

On Tue, May 26, 2020 at 10:01 AM, Chuck wrote:
Gary,
Thank so much for that, I'm glad you've already had success with the very design I'm building!

I did obtain the 140mm x 8mm rods from a different source since sufficient quantity wasn't available from the eBay seller.
https://www.rf-microwave.com/en/ferrite-rods/171/

These are Chinese made rods sold by an Italian company.
Chuck,

Thanks for the additional information about the Chinese-made 140mm x 8mm ferrite rods.

Unfortunately, since my  own FSL was constructed with the Russian surplus ferrite rods ordered from a seller in the Ukraine ("alexer1" on eBay), the coil turn information that I gave you may not apply to a an FSL constructed with Chinese rods. The number of coil turns is related to the permeability of the ferrite rods, and Chinese-made rods typically have significantly different permeability than either Russian surplus or Amidon ferrite rods. So you will probably need to fine tune your own antenna's FSL coil because of the Chinese-made ferrite rods. Sorry! 

If a DXer uses the exact same components that I did for my FSL antenna then he would be able to simply construct it in an
identical way, and probably come away with identical performance.

73, Gary



  


Re: New Parts for FSL and Air Core PVC Loop Antennas

Chuck
 

Gary,
Thank so much for that, I'm glad you've already had success with the very design I'm building!

I did obtain the 140mm x 8mm rods from a different source since sufficient quantity wasn't available from the eBay seller.
https://www.rf-microwave.com/en/ferrite-rods/171/

These are Chinese made rods sold by an Italian company.
I ordered 30 of the BF-51s @ $1.83 a piece last week. The big extra expense was DHL international shipping, which was about $38 to my Northern Virginia location. I received them yesterday, they were packed well (none broke), and seem fairly straight and well constructed.
Their online inventory shows there are still 348 of these units in stock in case anyone else is interested.

Best,
Chuck


Re: FSL Antenna Tuning Course Video

Todd
 

Thanks Gary for both the instructional video, and informative technical construction details.

Based on all the factors involved, I suggest that building an FSL antenna is much more challenging than operating the finished product.

The critical FSL tuning is largely overcome by using a 8:1 reduction drive 384p variable capacitor. The tuning sharpness in the video is similar to my 40 inch PVC box loop. Of course the tuning is even sharper down near the bottom of the MW band, e.g. 531 KHz. But I have never had issues re quickly finding the loop resonant signal peak.

Like any loop, the optimum induction distance is a function of RF frequency. At first, I position the portable radio a little too far away from the loop, carefully tune to resonance, then gradually position the radio closer until the loudest signal is obtained. The tuning sharpness tends to be greater with distances marginally too far for the loudest signal.

With the 40" air core loop, all my portable radios receive stronger signal induction when positioned center broadside to the loop. Directly back or front of the wires also works, but the signal level is not as strong.

I gather your backyard 9 foot air core PVC loop is the benchmark antenna for comparing all your other antennas. Is it possible for say a 7 inch FSL to match the 9 foot PVC loop? The benchmark is daytime stable groundwave. But with all the recent metro stay-at-home resultant consumer electrical noise, the bigger 9 foot loop may only produce more signal and noise. Hence the law of diminishing returns kicks in.

Kevin Schanilec's FSL optimization paper states that the FSL antenna can provide the same level of performance as an air-core loop 12 times the size. Hence a 7 inch diameter FSL could be expected to approximately perform to a 7 foot air-core loop. The Belrose equation says the air-core loop will provide more signal. But the equation doesn't factor in all the variables. It is only by trial that the more efficient antenna can be determined.

Regards,

Todd

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