Brian needs more power... any suggestions ?

[BriansBrain]

Aha!! The gain of "5.15 dBi" is actually fractionally less than 3dB over a dipole. The "dBi" figure is the theoretical "gain" over a non-existent "isotropic radiator".

That is what I said/quoted - I measured a 3db Gain over the Dipole I had on the same power.

Your "Dominator" aerial is just a slightly shortened ⅞-wave job - shortened to make it match 50Ω - with that weird "halo" matching transformer. It works just the same as a ¾ J-pole - the upper ½-wave part does the radiation, the lower bit is just for the match!

I know, I have read all about..... and it's much less inconspicuous that the Dipole I had on the mast before.

Depending upon the altitude of your site, you could consider a "Slim-Jim" which would give very similar results, and would cost next to nothing to make! It's possible to engineer the Slim-Jim to give a sloped radiation pattern - we've used them from high sites with a falling radiation shape to get coverage into nearby inhabited valleys.

Why would I change for something that gave similar results.


+ There you go with the Make again - where the fuck would I make it ?

You really should consider "aiming" your signal towards the centres of population - there's no point whatsoever of broadcasting out to sea, and you could redirect that otherwise wasted power to where you really want it to go!

I have answered this before

I want / need Brian to to be / stay omni directionall.
Even though my main listener area is Playa del Ingles / Maspalomas area.
I have had reports that he is available in many parts of the Arguineguín area so I don't want to lose those listeners.
Many residents and tourists drive up into the mountains at and inform me they are surprised and glad to receive him.

Conclusion: I would like to stay with the Dominate.

Albert... With all due respect... you should actually read what I say in my posts and not just air your opinion.

[Krakatoa]

I think you have a complicated location.
Maybe find a friend to host a repeater tx?

[jvok]

Don't see how a directional will help given the towns you want to cover are spread over near enough 360 degrees. I guess you could stack two of the dominators as a collinear to get vertical gain without losing anything horizontally, but doesn't exactly help with the visuals or the wind loading.

I think your only other answer is more power. Dutchrfshop have a 500w board with 2 push pull mrf300s for just over 200euro. You could get put that board in a box with a psu and all the connectors for less than 350 total.

[BriansBrain]

I think you have a complicated location.
Maybe find a friend to host a repeater tx?

Yes... I have thought about that to cover the Arguineguin area.
But....... nobody I know is in the right location could do it
I will keep looking

[BriansBrain]

Don't see how a directional will help given the towns you want to cover are spread over near enough 360 degrees.

Yes your right I need cover +/- 250 degrees.

Brian + 250 Degrees-2.JPG

I guess you could stack two of the dominators as a collinear to get vertical gain without losing anything horizontally, but doesn't exactly help with the visuals or the wind loading.

I did think of that but... you nailed it... The visuals and the wind loading

I think your only other answer is more power. Dutchrfshop have a 500w board with 2 push pull mrf300s for just over 200euro. You could get put that board in a box with a psu and all the connectors for less than 350 total.

Yes, obviously I have been thinking of a bigger Linear but I need to find one with a better efficiency as that one works out
at +/- 63% and that's before it goes into a Low Pass Filter.
Then there is the efficiency of the power supply and consumption of the fans + Exciter and 10W booster linear amp.
Total efficiency would be down to +/- 50%

I have been looking at an the Elenos 1000W transmitters, they claim a total 74% efficiency.
Over a 4 year period this makes a big difference.
When it's just a non profit making hobby running costs have to be a priority.

[BriansBrain]

You should e-mail or phone Dutchrfshop, he has 3 of his 4 Watt in 500 Watt out modules in stock at €209, 1KW modules at €119 plus €169 for the MRFE6VP61K25HR6. You will need sundry items like a copper heat spreader, heatsink, output filter, fans, connectors, an enclosure and a power supply - he sells all that too.

The 1000W does look tempting as I'm planning to go for a 600W MAX output
Which will give me a 6db increase on what I have now so should be definitely noticeable

The specs say...

1000 Watt print for 87 to 108 MHZ.
Built-up PCB for BLF188XR or the MRFE6VP61K25HR6
The circuit is designed for high efficiency at 1000 watts.
Specifications with BLF188XR:
VCC: 50 Volts
Current : 25A (27A Max 1000W + )
Output Power: 1000 Watts

At 50V the max current in the specs for 1000W is 27A.
so at 1350W input for 1000W output the efficiency = 74%
Could I expect the same efficiency at 600W ?

Would you recommend to go for the BLF188XR or the MRFE6VP61K25HR6

[jvok]

Not sure where you're getting 63% from. The numbers on the Dutchrfshop site work out to 70-80% for both the 500w and 1000w boards. Running into a well matched load using good quality coax and short thick wires between the psu and amp should get you near the top end of those numbers. Fans, exciter, driver etc should only add a few watts each, nothing compared to a 500w amp. Add a decent smps and I don't think you'll have much trouble matching the elenos for efficiency.

In the end it really comes down to whether you want to bother building your own rigs or just buy something instead.

[yellowbeard]

According to the MRFE6VP61K25H FM Broadcast reference design from Freescale, driving that amplifier with 1 Watt will give 640-695 Watts out at 66-75% efficiency - the better figures are for 108MHz. That's some tremendous gain! I imagine the Dutchrfshop board has similar performance or he wouldn't have pricked with the design. The Broadcast Application Note is available on enigma shops page for the part:
https://www.enigma-shop.com/component/h ... wer-mosfet
I confess I almost got a boner reading that PDF.

[rigmo]

At 50V the max current in the specs for 1000W is 27A.
so at 1350W input for 1000W output the efficiency = 74%
Could I expect the same efficiency at 600W ?

Would you recommend to go for the BLF188XR or the MRFE6VP61K25HR6

MRFE is more ragged
https://www.facebook.com/groups/8646484 ... iles/files
efficency calculator.xlsx

[Albert H]

Albert... With all due respect... you should actually read what I say in my posts and not just air your opinion.

Matey - it's NOT "opinion", it's years of experience in many markets, from Europe to the USA, South America, parts of Asia and even Australia!

Your coverage looks (from the map) to need to cover about 200°, but not contiguously. The quickest way to get coverage that will show a significant field strength increase into the centres of population is to stack lots of Yagis with phasing harnesses. However, this would not be non-obvious, and would require a lattice tower! If we were doing this commercially, that would be the approach, and the incidental "spill" would cover the mountainous countryside for the benefit of the more adventurous types that would go off the beaten tracks!

If you're determined to stay omni-directional, you really should consider a vertical colinear - real gain for a lot less expense than running a hotter PA (with the expense of the hardware and then all the extra consumption).

When it comes to constructing aerials, you ask where you'd construct one? In our early days, we used to build aerials in my back garden, then take them to out "Testing Range" which was a nearby farm! We used a little 100mW tunable rig and drove 'round the farm measuring the field strengths!

Looking at the pictures of your "Brian" studio and the equipment you've set up, suggests that you want your station to have the best of everything. That should include the transmitting facilities and aerial(s). I appreciate that it's basically a "hobby" station, but you've obviously gone to a lot of effort to get most of it right. Give the station a better aerial to get an (almost) free power boost, with no increase in mains consumption!

[BriansBrain]

Not sure where you're getting 63% from. The numbers on the Dutchrfshop site work out to 70-80% for both the 500w and 1000w boards. Running into a well matched load using good quality coax and short thick wires between the psu and amp should get you near the top end of those numbers. Fans, exciter, driver etc should only add a few watts each, nothing compared to a 500w amp. Add a decent smps and I don't think you'll have much trouble matching the elenos for efficiency.

Because the Dutchrfshop site Specifications for the 500w are very vague...
Example...

Voltage 48v - 53V
Current 13A - 15A (max)

I took the MAX values of 53V and 15A = 795W @ 500W out = efficiency of 63%

However, if it's possible to get 500W out at 48v x 13A = 624W
= efficiency of 80% this should have been stated clearer on the site

In the end it really comes down to whether you want to bother building your own rigs or just buy something instead.

Actually in the end it comes down to which would be the more efficient TX

[BriansBrain]

The Broadcast Application Note is available on enigma shops page for the part:
https://www.enigma-shop.com/component/h ... wer-mosfet

Thanks a lot

According to the MRFE6VP61K25H FM Broadcast reference design from Freescale, driving that amplifier with 1 Watt will give 640-695 Watts out at 66-75% efficiency

OK.......... from the Freescale reference design pdf
(Brian is at 96.8 so I'll take the 98 measurements)
@ 98MHz - 1W in - Power out = 660W @ 68.5% efficiency
After that would be the Low Pass Filter and cable loss sounds acceptable
The proof would be in the pudding (as they say).

I confess I almost got a boner reading that PDF.

I have only gone through some of the relevant pages and I understand why
Same thing happened to me

.

[BriansBrain]

Would you recommend to go for the BLF188XR or the MRFE6VP61K25HR6

MRFE is more ragged

Right...... I looked it up

Dictionary
Definitions from Oxford Languages
ragged
1.(of cloth or clothes) old and torn.
"a rough-looking man wearing ragged clothes"
2.
having an irregular or uneven surface, edge, or outline.
"a ragged coastline"

OK Thanks

https://www.facebook.com/groups/8646484 ... iles/files
efficency calculator.xlsx

?

[BriansBrain]

Your coverage looks (from the map) to need to cover about 200°, but not contiguously.

If you looked at the picture I posted a it's actually +/- 250 degrees.

The quickest way to get coverage that will show a significant field strength increase into the centres of population.

I'm not bothered about the centres of the ''Main'' population areas, they receive Brian fine,
it's the fringe areas I'm concerned about.

Stack lots of Yagis with phasing harnesses. However, this would not be non-obvious, and would require a lattice tower! If we were doing this commercially, that would be the approach, and the incidental "spill" would cover the mountainous countryside for the benefit of the more adventurous types that would go off the beaten tracks!

Impossible to have any sort of lattice tower.
If I did that the Guardia Civil would show up within 20 minutes,
break down the door and insist I take the construction down at Gun Point
confiscate and impound all the equipment appertaining to the station until I supplied
them with legal paperwork regarding an operating licence for the Brian

If you're determined to stay omni-directional, you really should consider a vertical colinear - real gain for a lot less expense than running a hotter PA (with the expense of the hardware and then all the extra consumption).

Firstly when on a mast this vertical colinear does it look like a Dipole
The Dipole I had on my mast before I took down and replaced it with the Dominator because...
I was told by many people, it's obvious you have a radio transmitter on that antenna and you
will get reported.

When it comes to constructing aerials, you ask where you'd construct one? In our early days, we used to build aerials in my back garden, then take them to out "Testing Range" which was a nearby farm! We used a little 100mW tunable rig and drove 'round the farm measuring the field strengths!

If I went out to go in the middle of nowhere on Gran Canaria with a test rig and antenna to do some field strengths
someone would see me report it to the authorities.
Response time for matters of national security of the ARMED Guardia Civil is very fast.
I/we would be arrested and held until I/we could explain why and what I/we were doing *IN SPANISH*

Looking at the pictures of your "Brian" studio and the equipment you've set up, suggests that you want your station to have the best of everything. That should include the transmitting facilities and aerial(s). I appreciate that it's basically a "hobby" station, but you've obviously gone to a lot of effort to get most of it right. Give the station a better aerial to get an (almost) free power boost, with no increase in mains consumption!

OK
Give me a link to where i could purchase (NOT MAKE) a better antenna than the Dominator
that is just as unobtrusive, with the same or less wind load, and that that can handle at least 1000W.

[rigmo]

I noticed that you don't understand what efficiency is... take a look at the calculator

[BriansBrain]

I noticed that you don't understand what efficiency is... take a look at the calculator

Compared to the RF amplifier Efficiency calculator efficency calculator.xlsx from
that facebook page the only thing I was not taking into account was Idle Bias

For example... the example on that page...

26V
8.5A
180W (RF)
Bias Idle Current 50mA
Total Consumption = 221W with 81% efficiency

I would of worked it out to be 81.44796380090497% Efficency

I could live with a 0.44796380090497% discrepancy

[BriansBrain]

I noticed that you don't understand what efficiency is... take a look at the calculator

OK
Here is a Efficiency Calculation example using efficency calculator.xlsx

efficency calculator.xlsx.JPG

This is from Freescale Semiconductor

efficency calculator.xlsx.JPG

[rigmo]

Yes but You can do fine tune, match and reach more efficiency.. input and exit of amplifire.. right for you transmitted frequency.. less power go to heating... i believe them made 67.7 is for broadband amplifiers..

[sinus trouble]

Fundamentally, Albert is correct!

Efficiency figures mean nothing if the amplifier loading is shite! Antenna are a f*ckn pain to get right!

Even if you had a mythical 100% amplifier installed! The antenna would still be the weakest link!

Just because something is so called "Professional" It will still need adjusting to its environment!

[sinus trouble]

Personally, I would use a dipole with a rear reflector element directed towards the Urban areas and away from the mountainous ground!

Either way? It will need onsite adjustments to get the best results!

Thats just my opinion?