DX Engineering ARV2 Active Whip - Report

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mstephens741

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I'm looking forward to your review of the Pixel when it finally arrives in comparison to the ARAV. My ARAV consistently outperforms my Pixel and would like to hear of your experiences of the two.
I can't wait. I am hoping for early next week, but no specific word yet. I am lucky to have the choice. As I gain a little experience, I think this antenna is working quite well considering my awful noisy location.
 

Token

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Meant to get back to this thread earlier, but lost track of it. Responses below are not an argument or an attempt to fuel one, just the way I see the hardware.

I am not an RF engineer, so I will not offer that kind of opinion.

I am an RF Engineer, with more than 35 years in the field. However, as most of my professional history is at frequencies significantly higher than HF I might have a bit of a bias against lower quality or marginal quality connectors.

The position I stated before is my opinion, and what I have found to be true, both in professional use and in hobby use.

But I have designed dozens of electronic devices in the field of audio, and I have also manufactured them for profit, and owned those businesses. So, I feel competent to offer an opinion about cost strategies in general. Yes, the RCA connector would cost some cents less than another connector. But no, that cost saving probably is not the reason it was used. You wouldn't use 150 high quality parts, and then toss in one cheap one to save a few cents as a cost strategy. That would make no sense to anyone in business. I suspect they could use any connector in that spot they wanted without undue concern over their profit margins. IMO, it was used because they considered it to be the one which would offer the most convenience to their users. I didn't know that, because I have never owned a SW receiver before.

I can only back that up with their message to me, which says in effect that for "receive only" radios, they considered the RCA to be the most common. Now, if that's incorrect - so be it. But I don't see it as useful cost reduction when there are dozens of other opportunities to lower the cost far more substantially without attracting the least bit of attention.

Unfortunately that statement (RCA is the most common used in receive only radios) does appear to be incorrect. RCA appears to be a very small minority in the currently , or recent past, available receive only radios.

For example, looking at the currently available line-up of radios on the Universal Radio Inc web page (by no means authoritative, but probably a good starting place as an example of market population today) of 11 radios listed in the Shortwave Tabletop category only the Ten Tec RX-320D uses an RCA for an HF antenna, everything else is either BNC or UHF (PL-259 / SO-239), except for the alternate high impedance input for the R-75, which is a spring clip input. A quick look through 20+ portables resulted in several odd antenna connectors, from BNC to clip terminals, but not one RCA that I saw.

RCA is simply not used very often today for HF radio applications, and has not been for decades. As far as I can tell it was never used by the majority of radios, although it used to be more common than today.

The only advantage RCA offers today, for this kind of application, is in cost. At its best, with regards to performance, it is "as good as" the next cheapest thing, and it is never better than something like a BNC, TNC, UHF, N-Type, SMA, etc. It can be argued that RCA is also more convenient, but that is personal preference. It can be easier to build cables for at home.

I should clarify for all. There are no RCA connectors on the DX Engineering ARAV. They use F connections on their matching unit (as does Pixel and likely Wellbrook).

No, the Wellbrook does not use F connectors. I know you said “likely” and were not making a hard statement, just adding to your knowledge base here. The Wellbrook (at least my 1530+) uses BNC and UHF connectors only.

Personally, I use RCA adapters on my Pixel and the ARAV in the house for quick disconnection during a storm. Never had an issue. I always make comparisons before I make a switch such as this. I'm sure there's some gadget somewhere that will reveal that I'm losing something in the process, but my ears sure can't tell. Adapter or no adapter - sounds the same to me. Weak signal reception doesn't change. The Excalibur reports the same signals across the board rather or not I use RCA adapters. Perhaps I'm missing something. I would be interested in hearing thoughts about RCA adapters, as the main focus seems to be a direct RCA on a receiver itself, rather than using them as adapters. Though I would have to imagine that if impedance matching is a concern when they are present as an antenna input on a radio, then using RCA adapters would be a concern as well

When RCA connectors are new and in good condition, and at HF frequencies, any difference in a receive only application will be negligible. Sure, it might be able to be measured, but in real life, for most people, it makes no difference.

The problem with RCA, as I have seen them in use, is as they age they tend to degrade performance faster than BNC or UHF would. This is particularly true if you are cycling them often, as in disconnecting the antennas when you are not home or when a storm approaches.

As I said earlier RCA is relying on friction fits for both mechanical and electrical connectivity. This friction fit often loosens with age. As the connection loosens there starts to be a performance hit. But because this happens slowly, over time, the user might not notice a change. It is often not until a problem becomes large and is noted, then the connector replaced, that the user has that “ah ha!” moment of realizing there had been something going on for a while.

It is primarily because of this more rapid degradation over time that I refuse to use them, even in a receive only HF application, unless there is no other possible answer. I have replaced OEM RCA’s on equipment with BNCs several times just to get around this issue.

I'll also mention that there was quite a discussion on another board concerning the use of RCA adapters. After reading those comments, I decided to use them as I prefer to pull rather than unscrew when weather gets ugly.

For quick release the RCA is certainly preferable to something like UHF, however they are really no faster than BNC to disconnect. With BNC you just twist and pull. Of course, with RCA you can just yank the wire, without touching the connector itself, but you really should not be doing that to any kind of plug/wire, let alone coax.

T!
 
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prcguy

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I agree the choice of RCA is odd and not justified today due to its limited use. However, RCA can be a very good RF connector and was used extensivly by Collins and other high end mfrs who were not skimping, RCA is smaller than most RF connectors available at the time.

I have serviced countless Motorola and GE Master series repeaters where Teflon insulated RCA connectors are used at 500MHz with 100w or more power, so there should be no concerns with RF performance at HF.
prcguy
 

chrissim

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I'm a history teacher and would never attempt to debate Token's knowledge and experience in a technical regard. However, I am confused by a couple of statements.

Token mentioned that RCA is only as good as the next cheapest thing, and never better than something such as a BNC, etc. Token also mentions that the use of an RCA in HF applications for receive only will result in only negligible difference, if that.

If I were grading a student's paper and such conflicting statements were present, I would be slightly flustered. There is conflicting information here because both elements can be inferred to mean something different. Either the thing is up to snuff or it's not. If it is, and by Token's statements using one would garner practically no difference, where's the debate or point of merit? The conclusion of reason here is that they are inserted into an application to save cost. Point taken there. In terms of performance decrease, there seems to be none, unless the RCA gets worn. In such a situation, I'll spend the $5.95 USD for a new one every couple of months to put my mind at ease.

Personally, I'd like to see everything accept a PL259, but unfortunately the "standard," if we may call it that, isn't always the standard, regardless of cost. I don't think many of us here would call the Pixel or DX Eng. antennas cheap, yet neither incorporates an SO 239 for obvious reasons - space limitations in regards to design concepts.

Again, I have to stress that Token's information is extremely valued and in my opinion, unparalleled on this board. But I also have to question the purpose of information when statements are made such as saying something is cheaper and not good enough but performs the same as something better.

In the end, please forgive me as I am not attempting to be argumentative. What would help those of us who have not been involved in this hobby for ages is straight talk. The majority of the thread where RCA is involved could have been summed up simply: "RCA is cheaper and will not last as long, but using one for HF receive purposes is fine."
 

Token

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I agree the choice of RCA is odd and not justified today due to its limited use. However, RCA can be a very good RF connector and was used extensivly by Collins and other high end mfrs who were not skimping, RCA is smaller than most RF connectors available at the time.

I have serviced countless Motorola and GE Master series repeaters where Teflon insulated RCA connectors are used at 500MHz with 100w or more power, so there should be no concerns with RF performance at HF.
prcguy

Sure, my Collins KWM-2 has RCA connectors on the back of it, not only for accessories but also for the antenna connections, of course it would have been much more difficult for them to get all those connections on the back if they had used anything but RCA, I suspect size was the driving factor in that application. Several other of my 50’s, 60’s, early 70’s vintage gear is also RCA heavy, although still a minority for RF connections. Although I have not taken it out of storage for years I want to say my SB-301/401 station also uses RCA’s. In newer gear even my Kenwood TS-2000x has one for the receive only antenna.

I have seen RCAs used in many military applications and modern gear, from high power communications stuff to radar systems. One thing the majority of these high end applications have in common is that the RCA connecter is often used in a low stress or static location. Such as for IF strips in radar systems or sat comm gear, jumpers from exciters to high power amplifiers, and various internal connections (as I would think most likely in the repeaters you mention).

No one is saying they won’t work, I only said the use of RCA is unusual today, the vendor stated reason for selection of RCA is based on probably incorrect data (assuming the statement was not an error), I would not use one if I had a choice (my opinion), and in my experience they do have a higher failure rate under some common conditions than many other options on the market today.

T!
 
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Token

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Token mentioned that RCA is only as good as the next cheapest thing, and never better than something such as a BNC, etc. Token also mentions that the use of an RCA in HF applications for receive only will result in only negligible difference, if that.

If I were grading a student's paper and such conflicting statements were present, I would be slightly flustered. There is conflicting information here because both elements can be inferred to mean something different. Either the thing is up to snuff or it's not. If it is, and by Token's statements using one would garner practically no difference, where's the debate or point of merit? The conclusion of reason here is that they are inserted into an application to save cost. Point taken there. In terms of performance decrease, there seems to be none, unless the RCA gets worn. In such a situation, I'll spend the $5.95 USD for a new one every couple of months to put my mind at ease.


Look at the full context of what I said, specifically “When RCA connectors are new and in good condition, and at HF frequencies, any difference in a receive only application will be negligible”.

They can initially be as good as, but not better than (leaving out a size savings, if that is important to the application), some more expensive options. However I also said “as they age they tend to degrade performance faster than BNC or UHF would”. This degradation tends to be gradual and very possibly might not be noticed by the user until it has progressed significantly and been a factor for some time.

I don’t see anything conflicting in that.

The point of what I was saying is that I have seen failures far more often with RCA than with any other kind of RF connector particularly when the connector is cycled often, such as when used to disconnect antennas in the event of storms or when unattended. And these failures absolutely can result in performance issues that are very real, but not always immediately noticeable to the user who is not continually taking measurements and making comparisons. These failures are not always visibly detectable.

I have also seen RCA connectors perform well for decades, however this tends to be under conditions of no mechanical strain and limited or no connection / disconnection cycling.

You may be willing to replace it often, but if losses increase gradually over time (as they can do) at what level, or under what conditions, will you notice the increased losses? If you are performing comparative measurements you may find it quickly, but are you, or any other user, really going to do that often? If your losses increased by 10 dB over a period of one year would you notice it, and if so based on what? I am not saying that last is probable at all, it is only an example for consideration.

The points of merit, while initial performance may be a wash:
- There is no real quantifiable advantage to using RCA connectors for RF, except for cost (the size savings of the past are not still a factor, several very good, but typically expensive, RF connectors are smaller than RCA)
- RCA connectors in a dynamic application tend to fail more frequently than other more commonly used RF connectors
- RCA connectors often fail in ways that are not immediately obvious to the casual user, in my personnel experience this has been more common with RCAs than with almost any other type of connector



In the end, please forgive me as I am not attempting to be argumentative. What would help those of us who have not been involved in this hobby for ages is straight talk. The majority of the thread where RCA is involved could have been summed up simply: "RCA is cheaper and will not last as long, but using one for HF receive purposes is fine."

I would tend to say it as “RCA is cheaper and while often acceptable when they are new or in good condition, they may not perform as well as other options for as long under some common conditions, particularly when cycled often. In RF applications they can sometimes perform in a degraded manor for significant periods of time before that degradation is detected by the user”.

Or if you prefer something along your statements lines: “RCA is cheaper but using one for HF receiving is fine, right up until it is not anymore, which will probably happen quicker than most other style of RF connectors in use today and may, or may not, be easily detected.”

Go back and look at anything I might have said in this thread. I did not ever say RCA’s could not, or even should not, be used. I said that based on my past experience I would not use them, I stated the reasons for that opinion, and I flatly stated that if any of my engineers or technicians suggested they be used in a project they better have a very good reason for it (and I can’t think of too many, if any), otherwise it is not happening.

T!
 
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