60m allocation and EIRP

[VK3ALB]

So one day we'll probably get the 60m allocation here in VK. I race out to the shed and whip up my squidpole supported vertical antenna for 60m, hook it up to my IC706 via 30 feet of thick coax I bought at a hamfest for $5 and I'm ready to go. Sadly I don't have an EIRP meter that goes to 15 watts.

What now?

[VK2ZRH]

Get out your slide rule and figure it out.

Can't find it? Buy a new one, here: http://www.sphere.bc.ca/test/sliderule.html

[VK3PY]

VK3ALB wrote:

Sadly I don't have an EIRP meter that goes to 15 watts.

It's alright Lou. Either does the RI! More importantly, how did you get your mythical '706 to transmit on 60m? Oh no....... let's not start that one again.

Chas
VK3PY

[VK2AAH]

Go on... lob that old hand grenade again....

[VK3ALB]

VK3ALB wrote:

Sadly I don't have an EIRP meter that goes to 15 watts.

It's alright Lou. Either does the RI! More importantly, how did you get your mythical '706 to transmit on 60m? Oh no....... let's not start that one again.

Chas
VK3PY

Hi Chas,

Google is your friend.

To enable full HF transmit:

IC706MkII G: remove diode D2030

IC706MkII: remove D108

IC706Mk1: remove D5806

(Possibly the mods for 706MkII and 706Mk1 are swapped, can't remember now)

Roger,

None of those slide rules have an EIRP scale.

Hint: I'm an old ham that's scared of the interwebby thingo so please no links. Surely someone has half an idea on how to go about this?

[VK4WDM]

I don't think we should hold our breaths waiting for a VK 60M allocation. 5MHZ is very heavily used in PNG, Solomons and Pacific Islands for intra-country government and health and safety comms and I have had personal experience of the QRM that occurs now.

There would have to be very serious discussions with those countries about the potential for ham interference to these vital services before Australia made an allocation for hams beyond maybe a couple of narrow data-only channels.

There has already been some previous discussion on other threads.

73

Wayne VK4WDM

[VK3PY]

Lou,

Thanks for the info. When the time comes (if it ever does) I'll go looking for that elusive diode in my IC-706MkIIG.

***************************************
Wayne,

I fear you're right. The services you cite want the 60m band for the same reason that it would be attractive to us. As we head towards solar minimum, there will be times when even in daylight hours, 40m won't sustain contacts. I also think 60m would be a great mobile band. That if we do gain access to it, we would only have a very narrow window, means that a mobile whip would adequately cover the whole band.

***************************************
Roger,

We know that EIRP calculations are easy, even with an abacus. The tricky bit lies in the assumptions we choose for the various losses incurred with some antenna systems. E.g. loaded verticals operated against "ground". Granted, some of these losses can be measured for a particular installation (not a simple matter), but what about portable operators who often employ a variety of makeshift wire antennas depending on their location?

73,
Chas
VK3PY

[VK4OX]

I'm thinking about splicing together about 50 slide rules, (Faber Castell), end to end, and running a wire down the centre.. That should be about a quarter wave on 60m...
I only need another 49...

Adrian, VK4OX.

[VK3QI]

Simple solution - ask Doug to update his EMR software with a radio button for 5 Mhz.

Assume a 1/4 wave vertical and appropriate cable loss - Lou you can use RG58!

Cheers

Peter VK3QI

[VK3ALB]

I don't think we should hold our breaths waiting for a VK 60M allocation.

Review my post Wayne, I said "one day". I'm quite sure it will take some time before we get onto 60m in VK.

Considering there has already been a number of comments about the 60m band both here and by the WIA and of course the ARRL in the last few days would it not be reasonable to at least think about how one would go about staying inside the guidelines? The consensus reached is for a 15kHz section of the band where the power limit will be specified in EIRP.

My scenario is probably not too far from the truth when the time comes. Some of the things you need to know are easy to find but as Chas said you need to make some assumptions about your antenna before you can come up with a solution. I could just assume a value for antenna efficiency so I can run my TX at 100W output? Is that enough? What if a radio inspector sees this post (I hear they're everywhere) and lumbers me at the next hamfest asking me to explain how I determined my 60m mobile installation was within limits? How will he determine if I'm staying within the guidelines? If a ham calls CQ on 60m will anyone hear him?

Posted in search of enlightenment

[VK4ADC]

If you assume a lossless dipole has a gain of 2.15dBi and the approved EIRP is 15 watts, then divide 15 watts by 1.64 (the power ratio that 2.15dB represents) and you get 9.146 watts of actual power.

The fact remains that feedlines, baluns, etc.. all introduce some losses, althought at 5MHz these values should be quite low. A nominal transmitter power of 10 watts is thus reasonable to allow for accumulated losses - including the fact that that a dipole is not actually lossless.

It becomes far more difficult to determine the outcome when basing it on a mobile facility as "ground effectiveness" and the power lost in that, plus the basic gross inefficiency of helical-style whips or even base or centre-loaded whips at HF. You may be able to run maybe 5 times the transmitter power (50W) and still meet the 15W EIRP criteria.

The last question you should ask is whether the 15 watt figure is based on PY or PX. So how much power can you run on CW or on SSB, or PSK etc... ??? Typically 10 watts regardless, unless more details are made available.

Something else to consider while you are mentioning removing diodes in that fabulous IC-706 series transceiver : The ACMA requires all "spurious" products to be -43dBc (dB below carrier level) for all transmitters operating below 30.0 MHz, including amateur products as far as I am aware. So what are the effective products levels that the 706-X produces when operated at 5MHz ?

By the way, those transmitter products include 2nd and subsequent harmonics, synthesiser and mixer products,..... and since the bandpass and/or low pass filters in the 706-X ( and most other amateur HF transceivers) are designed for operation of the transmitter at 1.8, 3.5, 7.0 etc MHz, the 5MHz point does not fit nicely within the filter structures so the -43dBc figure might not be met.

Note that all new amateur licensees are tested through their practical assessments to ensure they can adjust the output power of a transmitter, in the case of a Foundation prac to 10 watts PEP or 10 watts on FM. If they have to do it then surely an Advanced holder should be able to do the same - they are the only ones likely to access any segment that was forthcoming at 5MHz.

There are answers available : you just need to actually ask a question

[VK5ZLR]

I guess the ACMA will just give a power limit in watts, just like for other bands, doesn't particularly need to be specified in EIRP.

However its unlikely to be at the top of the ACMA's list of things to do, so we will have to wait.

Be good to have though.

[VK3AUU]

The Yanks just have 4 spot frequencies allocated according to my Flex 1500.
Approx 5.300, 5.346, 5.357 and 5.371. We might get the same deal, although not necessarily those spots so we will have to Tx on a different freq to what we receive on.
David

[VK4WDM]

I think WICEN already has a 5MHZ spot?

Wayne VK4WDM

[VK3ZAZ]

VK3ALB wrote:

Sadly I don't have an EIRP meter that goes to 15 watts.

It's alright Lou. Either does the RI! More importantly, how did you get your mythical '706 to transmit on 60m? Oh no....... let's not start that one again.

Chas
VK3PY

SHoot me
My FT2000D ex KL7 has ten 5 MHz tx channels at 50 watts AND also has the ALASKAN EMERGENCY CHANNEL TX in case I fell off my DOGSLED.

I listen daily but don't hear any MALAMUTTS.

PS
Don't buy an antenna Lou do a sweep of the old high schools at Colac and Morlake and see old tw dipoles we put in for the ill-fated SCHOOLS of the FUTURE HOMEWORK NET on 5 MHZ. You wills ee T2D,s ATN specials and SCALARS.
The MORTLAKE ONE is still up on the portable where I put it in 1992.
Heap of crap useless frequencies abandoned by everyone.
Even WWVH

[VK4EA]

5300 kHz, Derby and Port Hedland RFDS. Only a small part of the challenge.

Sent from my SM-T800 using Tapatalk

[VK4WDM]

Heap of crap useless frequencies abandoned by everyone.

Definitely NOT everyone Steve!

As I said earlier in the thread 5 MHz is the life blood (and it can literally be life blood) of the medical and health care network in PNG and has saved many lives (from personal experience). The propagation characteristic are excellent for NVIS contacts in steep mountainous country and country-wide communications during the day - I can receive the afternoon PNG health net here in Townsville on 5.76 MHz on most days. Night time is a nightmare due to the huge amount of QRM from everywhere and I would hate to see Australian hams add to that QRM. There are 3MHz channels available for night time use, but again QRM is a problem, as is heavy storm QRN during the wet season.

73

Wayne VK4WDM

[VK6ZFG]

5Mhz is an excellent band for daytime district coverage. That is why it was heavily used by commercial services. 5360 & 5300 are WA RFDS freqs so here lies a potential issue.

[VK3ALB]

Wow, only one of you has come anywhere near answering the question. I should have made it clear that I'm not interested in the merits of the band or who else uses it or even when we will be able to use it. I don't even want to buy an antenna. My point was that there was consensus reached at WRC-15 for access to the 60m band. The approval was for a 15KHz slice of 5MHz at 15W EIRP.

Regardless of if or when we get the band how does Joe Ham using his antenna analyzer with the color TFT screen work out how to adjust his transmitter so his system complies with the 15W EIRP limit? I know the calculation is easy but what I don't get is how to work out the efficiency of the antenna. Look back at my example - what if I said that I ended up with a centre loaded vertical with a couple of ground radials - where does one start? Let's just get in the ballpark for starters.

[VK4TI]

http://people.physics.anu.edu.au/~dxt10 ... s/Rrad.php
suitable vertical with a well built ground system will reach 90% efficiency ?