Date   

Re: End Fed antennas w/ uBITX #ubitx

Mike aka KC2WVB <rb5363@...>
 

My two cents are:

The mechanical analogy to this issue appears to be the transmission installed between an engine that revolves at several thousand rpm and the large wheels on the attached vehicle that revolve at 1 rpm. Sure, such a transmission can be built but how much power is lost in the transmission and never makes it to the wheels?

I think the best method for solving differences of opinion in this end-fed antenna conundrum is to set up controlled experiments that measure directly the radiated power emanating from the set-ups and then infer one's conclusions based on the acquired data and let the cards fall as is shown by the experiments.

On Wed, Jul 25, 2018, 10:53 AM iz oos <and2oosiz2@...> wrote:

Hi Jerry,
That way to measure the losses is the way I do as well when making or checking the actual losses of a impedance transformer. However what Warren is pointing out should be understood. He claims that the antenna you say is resonant is not. You see a low swr because of the losses inside the transformer (he says it becomes hot). If you measure the losses terminating with a pure resistor is simply not right. You should terminate with 50ohm but made with an infinite combinations or real an imaginary parts. This is what I have understood. I can't say it is right or wrong but if he says the trasformer gets hot, well I would not exclude he is wrong. Btw I use a T2FD 66 feet long on the HF and made thousands of qsos, several QRP as well notwithstanding many people say it is a whole loss antenna.


Il 25/lug/2018 16:34, "Curt M." <Kc3hjp@...> ha scritto:
I use a 44' end fed antenna exclusively except for some mobile contacts here and there.  I have well over 6000 contacts with my end feds.  The first 3000 contacts were made in a year and a half with a commercially made Ultimax 100 end fed.  The second 3000 are with my own home brew design and I've made those additional 3000+ contacts since the middle of January 2018 and it's now the end of July 2018.  Those newer 3000 contacts are about 40% SSB Phone and the other 60% are FT8.  The shocking thing is that my antenna is only 44' long and only 10 feet off the ground!!  I can work 80-10 and also 6m FT8 but once I start getting up into the middle or upper area of the 6m band my toroid is really rated that high and doesn't load up very well.

I will say that I use 100 watts more than I do 5-10w but I frequently use my Bitx40 or Yaesu FT-817ND and although the signal reports are a little lower, it's not uncommon to reach Europe with a 5-5 or 5-3 signal.  Often times I'll put the Bitx40 online and never even tell someone I'm QRP or that I'm using a kit radio.  Sure I don't get 5-9 signal reports all of the time but it's fun to work someone QRP and not even tell them.

I use an LDG Z-11PROII auto tuner with the Bitx40 and it works fine.  I will soon complete the build of my uBitx and can't wait to try it out.  
 
All antennas are compromise antennas, even a Mosley or SteppIR up 80' but you may be surprised what you can do with a decent end fed installed properly.  I think anyone that knocks an end fed antenna has either never used one or at least a properly designed/installed one.

Curt
KC3HJP


Re: VK3YE AGC pcb.

Alan Jones <oalanjones@...>
 

Hi Nick,
What EDA software are you using?

Al, N8WQ

On Wed, 25 Jul 2018 00:13:06 -0400, Nick VK4PLN <nickpullen@...> wrote:

Something I'm Working on...




73 Nick VK4PLN


Re: End Fed antennas w/ uBITX #ubitx

Doug W
 

On Wed, Jul 25, 2018 at 02:44 AM, Warren Allgyer wrote:
I am happy to supply test data and methodology, which has been independently corroborated, to any who wish to see it.
Did you test an actual antenna from the specific manufacturer in the review?
 
--
www.bitxmap.com


Re: End Fed antennas w/ uBITX #ubitx

iz oos
 

Hi Jerry,
That way to measure the losses is the way I do as well when making or checking the actual losses of a impedance transformer. However what Warren is pointing out should be understood. He claims that the antenna you say is resonant is not. You see a low swr because of the losses inside the transformer (he says it becomes hot). If you measure the losses terminating with a pure resistor is simply not right. You should terminate with 50ohm but made with an infinite combinations or real an imaginary parts. This is what I have understood. I can't say it is right or wrong but if he says the trasformer gets hot, well I would not exclude he is wrong. Btw I use a T2FD 66 feet long on the HF and made thousands of qsos, several QRP as well notwithstanding many people say it is a whole loss antenna.


Il 25/lug/2018 16:34, "Curt M." <Kc3hjp@...> ha scritto:
I use a 44' end fed antenna exclusively except for some mobile contacts here and there.  I have well over 6000 contacts with my end feds.  The first 3000 contacts were made in a year and a half with a commercially made Ultimax 100 end fed.  The second 3000 are with my own home brew design and I've made those additional 3000+ contacts since the middle of January 2018 and it's now the end of July 2018.  Those newer 3000 contacts are about 40% SSB Phone and the other 60% are FT8.  The shocking thing is that my antenna is only 44' long and only 10 feet off the ground!!  I can work 80-10 and also 6m FT8 but once I start getting up into the middle or upper area of the 6m band my toroid is really rated that high and doesn't load up very well.

I will say that I use 100 watts more than I do 5-10w but I frequently use my Bitx40 or Yaesu FT-817ND and although the signal reports are a little lower, it's not uncommon to reach Europe with a 5-5 or 5-3 signal.  Often times I'll put the Bitx40 online and never even tell someone I'm QRP or that I'm using a kit radio.  Sure I don't get 5-9 signal reports all of the time but it's fun to work someone QRP and not even tell them.

I use an LDG Z-11PROII auto tuner with the Bitx40 and it works fine.  I will soon complete the build of my uBitx and can't wait to try it out.  
 
All antennas are compromise antennas, even a Mosley or SteppIR up 80' but you may be surprised what you can do with a decent end fed installed properly.  I think anyone that knocks an end fed antenna has either never used one or at least a properly designed/installed one.

Curt
KC3HJP



Re: End Fed antennas w/ uBITX #ubitx

Curt M.
 

I use a 44' end fed antenna exclusively except for some mobile contacts here and there.  I have well over 6000 contacts with my end feds.  The first 3000 contacts were made in a year and a half with a commercially made Ultimax 100 end fed.  The second 3000 are with my own home brew design and I've made those additional 3000+ contacts since the middle of January 2018 and it's now the end of July 2018.  Those newer 3000 contacts are about 40% SSB Phone and the other 60% are FT8.  The shocking thing is that my antenna is only 44' long and only 10 feet off the ground!!  I can work 80-10 and also 6m FT8 but once I start getting up into the middle or upper area of the 6m band my toroid is really rated that high and doesn't load up very well.

I will say that I use 100 watts more than I do 5-10w but I frequently use my Bitx40 or Yaesu FT-817ND and although the signal reports are a little lower, it's not uncommon to reach Europe with a 5-5 or 5-3 signal.  Often times I'll put the Bitx40 online and never even tell someone I'm QRP or that I'm using a kit radio.  Sure I don't get 5-9 signal reports all of the time but it's fun to work someone QRP and not even tell them.

I use an LDG Z-11PROII auto tuner with the Bitx40 and it works fine.  I will soon complete the build of my uBitx and can't wait to try it out.  
 
All antennas are compromise antennas, even a Mosley or SteppIR up 80' but you may be surprised what you can do with a decent end fed installed properly.  I think anyone that knocks an end fed antenna has either never used one or at least a properly designed/installed one.

Curt
KC3HJP


Re: End Fed antennas w/ uBITX #ubitx

Jerry Gaffke
 

I have the unit that was reviewed.
Have checked it over with a vector impedance analyzer.
It is resonant on 80,40,20,15,10 as claimed showing low SWR as described in the article.
Including 40 and 20, you claimed that would not be the case.
And very high SWR in most regions out of those bands, indicating I am not just feeding a resistor.

Your central point seems to be you don't trust the transformers.
Yes, many such transformers are quite lossy.
In the review, they put two matchboxes back to back, so 50 ohms to 49*50=2450 ohms to 50 ohms.
Then monitored power going in from a transmitter, and going out to a dummy load.
Found there was very little loss.
How is this methodology deeply flawed?
 
You say you communicated with the folks who did the review.
Would be interesting to see if they agree with you.

Have you looked at the particular antenna system in the review?

Jerry


On Wed, Jul 25, 2018 at 12:44 AM, Warren Allgyer wrote:
Jerry

i am aware of that product review and I have have discussed the methodology with the author. Their methodology was deeply flawed and cannot be duplicated in a properly equipped test laboratory. 

The antenna is not the issue. The transformer is. When feeding a resistive resonant load the losses in the transformer are under 2 dB for bands 40 - 17, rising above 3 dB or 50% on the rest of the HF bands. 

When feedingING a non-resonant reactive load the transformer loss rises to 10 dB and more on all bands. I am happy to supply test data and methodology, which has been independently corroborated, to any who wish to see it. I am good in QRZ. 

WA8TOD


Re: VK3YE AGC pcb.

Paul Galburt - K2AYZ
 

Nice feedforward audio limiter/compressor. Back in the day, when I designed professional audio gear, I sometimes used packages like this

https://www.ebay.com/itm/Xvive-Audio-VTL5C3-Opto-Coupler-/331920576160

for such applications. The main limitiations were transfer curve repeatability from unit to unit, limited overall dynamic range, and somewhat slow attack time for some applications.

Ultimately designs based on log characteristics of semiconductors worked better (like THAT 2180 part).

LED/LDR work fine here, except that sharp spikes will sneak throught the attack delay.

I have a batch of about 50 odd 2180's left from the old days that I hope to press into this service. These were kicked out of production THD tests on audio consoles where the limit was 0.005% THD.

73,

Paul K2AYZ


Re: End Fed antennas w/ uBITX #ubitx

Don - KM4UDX
 

Looks like the FA-VA4 is no longer sold? I was looking at that...


Re: VK3YE AGC pcb.

MVS Sarma
 

LDR and LED can better be tucmed into a small black tube. That helps intercerence from external lighting.


On Wed, 25 Jul 2018 6:35 PM Dexter N Muir, <dexy@...> wrote:

It may have been done before: an opto-coupler driven in a linear-transfer range ... ? Certainly smaller and less susceptible to ambient light (opening housing, etc. ... Just alter a few resistor values here and there ... may also be more readily available: scrap an old PC power supply.
73
Dex, ZL2DEX


Re: End Fed antennas w/ uBITX #ubitx

Mike aka KC2WVB <rb5363@...>
 

Warren,

I don't have the test equipment to precisely measure radiation of power off an antenna so I have to rely on others that do....

In a past life I would use a fan dipole fabricated for 80 meters, 40 meters and 20 meters and perhaps 10 meters as well. I no longer have the capability to use a fan dipole and will either have to use an end-fed random or half-wave antenna or really accept losses by using an interior small magnetic loop. 

I don't mind using the small magnetic loop for listening but I'd rather give an end-fed a go for transmission purposes. So, just to be clear are you suggesting that an end-fed half-wave antenna cut for 80 meters, roughly 64-66 feet, is most easily accomplished by using a tuner constructed as an L or T or Pi network? Are you also suggesting that were you to use an end-fed random wire antenna as opposed to end-fed half-wave wire antenna that the tuner approach as opposed to a transformer approach is most likely to give you the least in terms of loss?

On Tue, Jul 24, 2018, 11:07 PM Warren Allgyer <allgyer@...> wrote:
Allison

i agree with most of what you said. 

I have made extensive tests of the most commonly used 49:1 transformer as well as VNA analyses of both random and resonant end fed wires. I have not tested 9:1 transformers. 

90% and higher losses occur using the 49:1 transformer on non-resonant wires. If the wire is resonant the losses drop to on the order of 20%. In both cases the measured VSWR is severely and favorably distorted by the transformer losses.

What you you say about harmonically related bands is true in theory but not useful for the directly related HF bands because of the shortening effect of multiple half waves in series. This causes the second harmonic resonant point of, for example, an EFHW wire resonant at 7.1 MHz, to be well
above the 20 meter band. The wire therefore when used on 20 meters will be operating in the non-resonant mode with resulting 90% or more losses.

The EF wire itself, both in resonant and non-resonant configurations is an excellent radiator. The challenge is to deliver power to it effectively. This can be done very well if the wire is resonant with a transformer. It can also be done very well across a range of bands if a tuner is used rather than a transformer.

If  you put 100 watts into a non-resonant antenna fed by the popular  49:1 FT-250-43 toroid transformer, key down for one minute, the transformer will be too hot to hold. If you do it at 500 watts the core will explode. On the other hand, used with a resonant wire and on bands 40 meters and above, the transformer will be Weston but not alarmingly so. 


Re: VK3YE AGC pcb.

Dexter N Muir
 

It may have been done before: an opto-coupler driven in a linear-transfer range ... ? Certainly smaller and less susceptible to ambient light (opening housing, etc. ... Just alter a few resistor values here and there ... may also be more readily available: scrap an old PC power supply.
73
Dex, ZL2DEX


Re: End Fed antennas w/ uBITX #ubitx

 

Thanks for sharing your experiences with "end fed" antennas... I forgot to tell you my most favorite 20 / 10 meter antenna is a resonant loop of zip cord, strung up in the attic, fed with 300 ohm twin lead to a 4:1 balun.  It's very quiet and has low SWR on 20 & 10 meters. Works great except when it rains: then the water on the roof acts like a shield.
  I have noticed a huge difference in my many experiments with 9:1 vs. 49:1 ununs.  That would be noise.  The 9:1 is seems to be much more noisy... Have others noticed this?
  I spent many years building various antennas for the low bands and VHF.  The one gadget that I purchased (built from a kit) last year that made my life much easier was a "Vector Antenna Analyzer".  I bought the FA-VA4 which covers 100kHZ to 100mHZ.  It tells you in an instant what your antenna is doing at a specific frequency (or frequencies).  If you're getting serious about improving your antenna, consider buying or borrowing one.
  I'm still playing with end feds and plan to change my external end fed which (just like someone else who commented) is hidden underneath the wooden deck railing that runs the length of the house, yet this morning!
Your mileage may vary,
Jim W0CHL


Re: End Fed antennas w/ uBITX #ubitx

Gordon Gibby <ggibby@...>
 

Wow, that is incredibly useful information.   My concern about some of these designs has always been poor design with too short a piece of wire.   

20% loss is probably around one DB, no big deal. Probably similar to using a trap.   8 dB is completely different

Thanks!

Gordon KX4Z 




On Jul 24, 2018, at 23:07, Warren Allgyer <allgyer@...> wrote:

Allison

i agree with most of what you said. 

I have made extensive tests of the most commonly used 49:1 transformer as well as VNA analyses of both random and resonant end fed wires. I have not tested 9:1 transformers. 

90% and higher losses occur using the 49:1 transformer on non-resonant wires. If the wire is resonant the losses drop to on the order of 20%. In both cases the measured VSWR is severely and favorably distorted by the transformer losses.

What you you say about harmonically related bands is true in theory but not useful for the directly related HF bands because of the shortening effect of multiple half waves in series. This causes the second harmonic resonant point of, for example, an EFHW wire resonant at 7.1 MHz, to be well
above the 20 meter band. The wire therefore when used on 20 meters will be operating in the non-resonant mode with resulting 90% or more losses.

The EF wire itself, both in resonant and non-resonant configurations is an excellent radiator. The challenge is to deliver power to it effectively. This can be done very well if the wire is resonant with a transformer. It can also be done very well across a range of bands if a tuner is used rather than a transformer.

If  you put 100 watts into a non-resonant antenna fed by the popular  49:1 FT-250-43 toroid transformer, key down for one minute, the transformer will be too hot to hold. If you do it at 500 watts the core will explode. On the other hand, used with a resonant wire and on bands 40 meters and above, the transformer will be Weston but not alarmingly so. 


Does Howard's Power Output Mod Work on V4 uBitx?

RowlandA
 

I got very good results using Howard Fidel's 3 component power output mod on my V3 uBitx.  Due to other changes I made to the V3 board, I am not getting any power out at all (not related to Howard's mod), so I have a V4 board on order.

Howard, is your 3 component mod compatible with V4 boards, given that Farhan made a change to improve the 10M RF output level?

Thanks and 73,
Rowland K4XD


Re: End Fed antennas w/ uBITX #ubitx

Dave Dixon
 

right on the money thats what i useed for the past 5 years portable with a youkits hb1 now being replaced with a ubitx V3 Dave G0AYD

On 24 July 2018 at 22:23, Jim Reagan <jimreagans@...> wrote:
Not trying to start a "antenna war", but I noticed several people on this forum use "End Fed antennas".(Like Allison KB1GMX).  I have also used them with good success.  I feed them with 33' of coax and a 1:64 unun (PD7MAA design).  I have one with a trap (again PD7MAA blog) doing multiple bands.
On QRZ, everytime a End Fed topic is brought up, there is a bunch of nay sayers that always chime in. What are you experiences with them and QRP?  I'd like to know, being limited by an HOA, for antenna structures.
Thanks,
Jim W0CHL



Re: End Fed antennas w/ uBITX #ubitx

Warren Allgyer <allgyer@...>
 

At one hundred watts, key down for one minute, into a non resonant wire, the transformer becomes too hot to hold in your hand. On SSB however the duty cycle is so low the transformer does not overheat. The loss is there nevertheless. 

WA8TOD


Replacement audio amplifier?

m5fra2@...
 

If you want an easy fix for low audio output this might be the answer.

They claim 2W +2W, yes it is stereo. They are £1.06 post paid on ebay,
I got mine at a UK radio rally for £2. Not much bigger than a standard
volume control pot.

 

I have not tried it yet, should complete the wire up today and will see

what the audio level is like. If it is low I will change the AF gain pot for

the amp.

 

https://www.ebay.co.uk/p/Pam8403-Gf1002-Digital-Amplifier-Board-2-3w-Stereo-Module-USB-Power-470uf/848723847

 

Colin – M5FRA


Virus-free. www.avast.com


Re: End Fed antennas w/ uBITX #ubitx

m5fra2@...
 

EFHW antennas are so easy to make and very cheap!

 

Colin – M5FRA

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Thomas Owens
Sent: 25 July 2018 03:02
To: BITX20@groups.io
Subject: Re: [BITX20] End Fed antennas w/ uBITX #ubitx

 

A local ham was disposing of a SK estate and had a EFHW8010 for a great price. I purchased it and some other items from him, hung the EFHW8010 in the trees and was so pleased I ordered a EFHW4010 to take with me for travel, or field use. I figured I'd hang it in the attic for bad weather use. Testing it out with my 7300 (antenna is in my attic mind you), I got the following decode results on FT8 a few weeks ago. I think I'll keep it, thanks :)

Image removed by sender.


Virus-free. www.avast.com


Re: End Fed antennas w/ uBITX #ubitx

iz oos
 

In any case transformer loss by 2-3 db is huge if compared to the transmission line transformers by Jerry Sevick (which uses three ferrites and a 150ohm line for a 450:50ohm unun).


Il 25/lug/2018 09:48, ha scritto:

If then, the transformer would become very hot. Is that the case?


Il 25/lug/2018 09:44, "Warren Allgyer" <allgyer@...> ha scritto:
Jerry

i am aware of that product review and I have have discussed the methodology with the author. Their methodology was deeply flawed and cannot be duplicated in a properly equipped test laboratory. 

The antenna is not the issue. The transformer is. When feeding a resistive resonant load the losses in the transformer are under 2 dB for bands 40 - 17, rising above 3 dB or 50% on the rest of the HF bands. 

When feedingING a non-resonant reactive load the transformer loss rises to 10 dB and more on all bands. I am happy to supply test data and methodology, which has been independently corroborated, to any who wish to see it. I am good in QRZ. 

WA8TOD



Re: End Fed antennas w/ uBITX #ubitx

iz oos
 

If then, the transformer would become very hot. Is that the case?


Il 25/lug/2018 09:44, "Warren Allgyer" <allgyer@...> ha scritto:
Jerry

i am aware of that product review and I have have discussed the methodology with the author. Their methodology was deeply flawed and cannot be duplicated in a properly equipped test laboratory. 

The antenna is not the issue. The transformer is. When feeding a resistive resonant load the losses in the transformer are under 2 dB for bands 40 - 17, rising above 3 dB or 50% on the rest of the HF bands. 

When feedingING a non-resonant reactive load the transformer loss rises to 10 dB and more on all bands. I am happy to supply test data and methodology, which has been independently corroborated, to any who wish to see it. I am good in QRZ. 

WA8TOD