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eHam Forums => Amplifiers => Topic started by: KG9ZTX on January 27, 2019, 09:03:04 PM



Title: 2m amplifiers???
Post by: KG9ZTX on January 27, 2019, 09:03:04 PM
Ok, first off I know we should only transmit with enough power to successfully be able to communicate without using more then we need.

Yet we are allowed to use up to 1500watts on VHF 2m bands.

The most I have ever seen  HT have is 10watts, the most in a mobile is 100watts.

I understand, that in a HT more power would mean shorter batter life and higher expense.

Even with mobiles there are vehicle restraints to some degree, then higher cost.

I have seen some VhF 2m amplifiers that can take a Radio to as much as 300 watts.

So am I to assume, no one ever transmits at 1500watts? That there just aren’t any vhf radios including repeaters that come anywhere close to transmitting and using that much power?

Please don’t assume that I am wanting more power in my radios or even feel the need to have that much power.

How much power does an AVERAGE repeater have?

How much power does it take to go any distance? Assume for that question, that there are no structures or trees or landscape blocking the antenna set at a height of 50’ and the only thing that would keep line of sight is curvature of the Earth. If that was the case, how much power does it take to go how far?

Does having more VHF power allow it to better punch its way through buildings and vegetation?


Title: RE: 2m amplifiers???
Post by: G3RZP on January 28, 2019, 03:35:48 AM
Those sort of powers were used on EME when people were using CW, and also for DX work on CW on 2m such as Hawaii to California.  The newer digital modes allow the use of less power, but some contest stations used (and possibly still do) up to 1500 watts output on 2 and 70cm, with big antennas. The only time I've operated in a VHF/UHF contest, I was on 70cms with about 1kW out and was having a QSO rate of 30 an hour over paths around 600miles - until the generator failed! That was as a visitor to a station on a hilltop in Maine.....


Title: RE: 2m amplifiers???
Post by: W9IQ on January 28, 2019, 04:11:25 AM
If there are no obstructions between them, two towers at 50 feet each will yield a reliable radio range of about 20 miles (32 km) on 2 meters. This of course assumes that both tower bases are at the same elevation.

If you place 1/4 wave ground plane antennas on the top of each 50 foot tower, use marginal coax cable to connect them to the transceivers, and use moderate quality transceivers, you will need less than 1 mW (0.001 watts) of power to communicate over the 20 mile path on 2 meters. If you could obtain a 100 mile line of sight path, you would only need about 20 milliwatts (0.02 watts) of power. Look up the Friis equation to learn more about this calculation.

Repeater output power (from the duplexer output) can run from 10 to 150 watts or more. Antenna system gain will typically raise this further. This "extra" power is to offset the effects of trees, buildings, terrain, rubber ducky antennas, etc.

High power amplifiers are typically used for simplex modes that involve reflected (e.g. atmosphere or moon) signals that are not simple line of sight communications.

- Glenn W9IQ



Title: RE: 2m amplifiers???
Post by: G8HQP on January 29, 2019, 06:40:40 AM
At VHF frequencies the world roughly divides into two groups: those within your radio horizon (you can communicate with them using a few watts), those beyond your radio horizon (you can't communicate with them at all). This simple picture is not quite true, because there are also:
1. people just on your radio horizon - a bit more power might just reach them, but a lot more power won't get you much further
2. people you can reach via distant reflectors (e.g. the Moon, tropospheric forward scatter) - for these you need high power
However, these people need high power too otherwise you won't hear them. Hence the general rule that quite low power (by HF standards) is enough for most purposes for VHF.

HF is different because you have more attenuation, you are almost always using distant reflectors and you have more local noise at the receiving end.


Title: RE: 2m amplifiers???
Post by: N8FVJ on January 29, 2019, 07:12:31 AM
50 watts vs higher power on 2 meters can help under certain circumstances. The ham may have his beam antenna pointed in the wrong direction and cannot hear 50 watts. The band is noisy and the extra power gets you out of the noise at the fringe range. Tall buildings in a city may block a lower power signal, but I do not have that issue. For most communications within line of site, 25 to 50 watts is enough power on 2 meters SSB. I use 350 watts on 2 meters for a little extra power with a 8dB dual band beam antenna.

I have not performed the math, but perhaps a 14-16dB gain beam antenna with 50 watts equals a 350 watt signal into an 8dB beam antenna. I just do not care for extremely narrow beam antennas as I may miss a signal.

1500 watts out on 2 meters makes for a very expensive amplifier and tube such as an 8877 tube. I'll pass.


Title: RE: 2m amplifiers???
Post by: AC2RY on January 29, 2019, 07:51:23 AM

So am I to assume, no one ever transmits at 1500watts? That there just aren’t any vhf radios including repeaters that come anywhere close to transmitting and using that much power?

1.5kW is needed if you are serious about using tropospheric scatter for propagation beyond line of sight (up to several hundred miles). Though you likely need to go higher in frequencies all way to GHz to make higher gain antennas to augment high power.

This mode is commonly used for land based military communications.


Title: RE: 2m amplifiers???
Post by: W4KYR on January 29, 2019, 08:22:00 AM
I knew someone in Northern NJ that used a 160 watt amp and a 10 element antenna who regularly got out to New England on 2 meter SSB, he told that he used to have almost regular QSO's with someone in Rhode Island.


Title: RE: 2m amplifiers???
Post by: W1VT on January 29, 2019, 08:25:39 AM
http://manitousys.com/home/products/communications-amplifiers/series-la-communications-amplifier/
Here is a company that makes 1500W 2M amplifiers.  I don't know how much product they sell.  I know the former owner/founder sold amps until he passed away.

https://qrznow.com/the-vhfuhf-dx-book-2017-replica-edition-is-now-available-for-free-download/
This book describes how to build and operate high power tube type amplifiers in great detail.
The UK limit is 400 watts, but really, there isn't all that much difference between 1500W and 400W aside from the cost of the tubes.



Title: RE: 2m amplifiers???
Post by: WB2WIK on January 29, 2019, 11:02:13 AM
A lot of moonbouncers still run 1500W output power.

My own 2m amplifier (homebrew dual 4CX250Bs) runs 1 kW CW output or about 800W PEP on SSB.

FM users rarely if ever run power close to that.   If "one" did, it would make him an "alligator" (big mouth, small ears) so lots of stations would hear him, but he wouldn't hear them unless they could also run that power level -- which would be very rare.

Most 2m repeaters run in the 50W - 100W output range.

Handheld rigs running more than about 7W output are rare due to battery limitations, but also due to heat dissipation limitations.   If the radio gets so hot you can't hold it comfortably, it's no longer realoly a "handheld." :D


Title: RE: 2m amplifiers???
Post by: KA4WJA on January 29, 2019, 11:39:21 AM
Gary,
Here is a pic of my 1200 watt 2m amp....the grey box on top of my Alpha 77...
It runs a pair of 8874's / 3CX400u's, and makes 1100 to 1200 watts, cleanly...on CW and SSB...and while could run 800 - 1000 watts intermittently on FM, it's rated for 400 watts continuous-duty for FM broadcast....
(https://cdn1.imggmi.com/uploads/2019/1/29/394767b0630b31ccdb7ba9ec6ad26359-full.jpg)
 
It's a Tempo 2002, from 1979, that I bought used in 1983 (for about the cost of the tubes, and I got a spare pair as well...)
It's 40 years old, and with original tubes still outputs 1100 - 1200 watts....and never a hick-up!

I used it on 2m EME (moonbounce), that's about a half-million miles, round trip!! and also on some long-haul 2m tropo-scatter work (800 - 900 miles)....and of course on a few 2m Es openings, and one GREAT evening of 1500 - 2000 mile F2 opening....and occasionally used it for just some local tropo work (300 - 400 miles)....I had 4 long-boom yagis on Az/El drive, at 50'....fed with 7/8" Heliax and tower-mounted GaSFET rec pre-amp (that I blew up twice, before I made a good sequencer!)



Now, as for your actual questions...

As some have noted, high-power "2m amplifiers" are a rare breed....but, not just because the need is small (just long-range troposcatter and moonbounce), but also because of the expense ($)...and the knowledge / care needed to design or build one...

{FYI, most modern ham repeaters are 25 to 50 watts, with some few wide-area-coverage repeaters (like mine) having 100 - 125 watts....and a few with extra long/lossy feedlines, might be 250 watts, that's about it....repeater coverage is all about antenna height (above average terrain), and sometimes about antenna patterns, but usually the transmit power never needs to be much more than any mobile radio attempting to use it...}

The origins of "high-power" VHF and UHF amateur radio amplifiers have their genesis in military surplus VHF gear, as well as some old "mobile phone" gear....this was in the 1950's, and the best most could do was a pair of 4x150a's and about 500 watts out, from military surplus VHF / UHF transmitters/amps....but most had only 100 - 250 watts from single tube amps....
Take note that some of these were actually Class C amps, so were just for CW....(or FM)

Some even used high-power "triplers" to get on 432mhz, from a 144mhz CW transmitter....and then added a 4x150a or even a 4cx250b PA stage...

Much of this was homebrew, with some modified military surplus VHF/UHF transmitters...

As things progressed the 4CX250b became readily available to hams (that means it was CHEAP!) and that meant that some hams designed and built single-tube amps with ~ 200 - 300 watts out....but they had issues with stability....so, even though this was always the place for only those with knowledge and experience, it was now an issue for even the best of the best, to make sure their VHF and UHF amps were not just high-power out-of-band oscillators!!

In the 1960's some "plumber's specials" and "strip-line" tank circuit designs were made, that allowed for a fairly stable high-power amplifier....
(and, around this same time, most non-amateur VHF/UHF systems were never more than a few hundred, to 500, watts...so, except for the BIG tubes and amps used for multi-kilowatt FM Radio Broadcast and VHF TV Broadcast, 500 to 600 watts was about all that could be done for most hams...)
So, a pair of 4cx250b's became the standard high power vhf and uhf amateur station's set-up...and from the 1960's thru the 1980's, this was "normal" high-power...

Now, please remember, that the FCC rules back then only permitted 1000 watts DC plate input power (there was no output power rule, back then), and as such typical max "legal" output was about 600 watts...
So, that's what most high-power stations had!

 

Then in the late 60's, there was a "relatively" affordable new tube, from Eimac....the 3cx1500 / 8877...which was capable of 2000+ watts output thru 250mhz, and actually worked well thru 450mhz (producing 1500-1700 watts out, at 432mhz, if you had an adequate power supply)

But, who had one of those new tubes??
Well, the answer was Bob Southerland, W6SAI (later, W6PO)....Bob worked for Eimac...
And, in the late 60's he designed a vhf amplifier (and a uhf amplifier) using this new tube...

He wrote of his amp, including schematic, and construction details in 1971....and the ham community now had a somewhat affordable, higher-power tube / amplifier....and it was wonderfully stable, very clean, and high-gain as well....
{and, btw, almost 50 years later, is still considered to be THE definitive 2m high-power amp!}

http://www.w5un.net/8877-1.htm

(https://www.eham.net/data/classifieds/images/454123.jpg)

(http://3.bp.blogspot.com/-N_UqezWQIcg/UdmMbOKb0PI/AAAAAAAACFI/b3vST9ootis/s1600/8877+5.jpg)

(https://www.eham.net/data/classifieds/images/376030.jpg)


But, FCC rules still wouldn't allow more than 1000 watts DC input, so that meant that if you built an 8877 amp, you just said "I'm running an 8877"  or "I'm running a W6PO amp"....and everyone knew you were running 1500 - 2500 watts out....
NOBODY ever had an issue with that, ever....mostly because nobody ever heard these guys, unless you had an array pointed at the moon, as this was almost the exclusive use of this amp, 2m moonbounce!!  (most of those on 432mhz moonbounce were still using a pair of 4cx250b's...but a few did manage to build a 432mhz 8877 amp...and as the 8938 tube became available, 2000 watts on 432mhz was possible...)


Also in the early 1970's the "strip-line" design got a face-lift of sorts, with the K2RIW design....  
Started as a improvement of a UHF strip-line design, Dick, K2RIW designed what is still considered to be the best "small form" mid-power UHF and VHF amp!

http://www.g4ohv.com/k2riw.html

http://www.newsvhf.com/2m_stripline.pdf

{BTW, in college (1981?) myself and classmate built a K2RIW 432mhz amp, for a NE contest station...and we got a big power supply from the EE building, and it ran 800 watts out!!  And, I think it was stil running 20 years later....}


In the 1970's Pliumber's Specials tank circuits (where actual copper plumbing pipe is used as part of the tank circuit) were also very popular, especially for those desiring a "easier" construction project, or for "mass production"...
Yep, there were a few hams that made amps for others....and they were wonderful!
But, as of yet, there were still no real "high-power" (600 - 2000 watt) ham radio VHF / UHF amps made in "production"...(except for a few 6m amps??  and a few "mid-power" amps)
Well, that changed with Henry Radio...

Henry Radio (in California) rolled out their "2000" series of amps, using a pair of 8874's (the little brother of the big 8877)...
The "Tempo 2002" was 2m...the "Tempo 2006" was for 6m....and while I never saw one, the "Tempo 2004" was for 432mhz.... (and they also made a "Tempo 6 n 2" which did both 2m and 6m)
These all have a huge / heavy-duty power supply, and run a pair of the high-gain, and very stable 8874's in grounded-grid, in a plumber's special design...
They make 1100 to 1200 watts out (with 40 to 60 watts of drive)...

Here is the pic of mine....
(https://cdn1.imggmi.com/uploads/2019/1/29/394767b0630b31ccdb7ba9ec6ad26359-full.jpg)


In the mid / late 1980's Henry Radio came out with their "3000 series"....the 3002, 3004, and 3006....these were their stand-alone console amps from 2m, 6m, and 432mhz, using the 8877 and a big power supply (and I think the W6PO design)...
I had a friend that had the 3002, and driving it with 80 watts, he had about 1900 - 2000 watts out...
The darn things were big and heavy....and expensive (~ $3500 in 1980's dollars)

{BTW, the FCC also changed the rules to "1500 watts out PEP" for all modes...so, that made those running big amps on 2m amd 432mhz, legal...well, almost "legal", 'cuz nobody runs an 8877 on 2m moonbounce at only 1500 watts, unless they're power supply-limited!! }

Here is a pic...
(https://www.eham.net/data/classifieds/images/546409.jpg)


In the 1990's Henry changed the old 2002, 2004, and 2006...to the 2002a, 2004a, and 2006a....when they changed from a pair of 8874's to a single 3cx800....
The 3cx800 had higher gain, and made construction/production easier, but...
But a pair of 8874's are more rugged than a single 3cx800, and there were some with tube failures, so Henry upgraded them (sold 'em) to the 3000 series amps....
The 2002a is a good amp, and will do all the original 2002 will do, but the 2002a is a bit more "dainty" and you need to be careful on that tube, so most will only drive 'em to 800 - 1000 watts out, so they get many years of service from them
{BTW, on a side note, my 2002 still makes 1100 to 1200 watts out, on ORGINAL 40 year old 8874's!!...only work I've ever done (other than cleaning it) was to replace the HV caps and rectifier sticks....and it keeps on purring along!}
 

Over the years, there have been others making very small quantities of 2m high-power amps...usually built-to-order, and not shipped right off-the-shelf....such as Lunar Link's amps...


You'll notice that none of the above are solid state??
The answer to why, up until the past 5 years or so has been that were not any real high-power solid-state devices that were affordable.....and for the most part, compared to tubes, that IS still true!!

But, with the introduction of reasonably-priced high-power LDMOS devices, some have tried to make 1Kw to 1200 watt 2m amps....but they haven't been successful...
Now, some here will quibble with that statement, saying that some were made....yep, that's true, but none were successful!!
Mainly due to "cost" / complexity, as well as heat dissipation, etc...BUT...

But, fact is the IMD of them was really bad....and while the FCC doesn't care about ham radio IMD, most of these 2m 1200 watts LDMOS amps couldn't pass FCC certification (part 15, etc.) nor harmonic regs....
{Two of my best friends did the FCC cert testing for some of them....and they were horrified by the crappy results, and crappy design/build....they found 3rd order IMD of only -18 to -20db(PEP)....and some harmonics were only 35 - 40 db down....true "CB Radio-type" performance...}

Of course, you could design and build a SS high-power 2m amp (whether MOSFET or LDMOS) that would be good (and clean), but so far nobody has one on the market....



Now, Gary, I do hope I cleared up the "mystery" of 2m amps??

As for "how much power does it take?"...well, as you can see, for most 2m communications 10 watts to 50 watts is all that is needed...with some needing 100 - 150 watts...
But, only a few (working long-haul tropo-scatter, or some still doing meteor-scatter, or the few doing moonbounce) using CW (or some SSB) have any need at all for any power over that....and as you can see, for moonbounce (CW) there's almost no such thing as "too much power"...  :)

{BTW, I personally don't consider computer-only-decoding modes (or computer-to-computer-only modes) to be actual real hams making contact....in my opinion it is computers making contact, not the human.....so, I haven't included any of the "negative signal-to-noise-ratio" / computer modes, like JT-65, JT-9, FT-8, etc., into any of my comments above....just CW, SSB (and FM)....'cuz if a human can't hear it, then a human isn't actually making that contact....just my opinion, so don't shoot me!}


73,
John,  KA4WJA


Title: RE: 2m amplifiers???
Post by: KA4WJA on January 29, 2019, 12:53:18 PM
BTW, I left out mention of the Dentron Clipperton V and the Gonset 903, 'cuz they're being discussed in the other thread here...
https://www.eham.net/ehamforum/smf/index.php/topic,1234.msg1111116.html#new

73,
John,   KA4WJA


Title: RE: 2m amplifiers???
Post by: G3RZP on January 29, 2019, 02:00:08 PM
Another area we haven't mentioned is Meteor Scatter and Auroral reflection where QRO helps. VHF and UHF isn't just the local repeater and the local area: there are a number of other propagation modes used to work DX, some of which have very high path losses, necessitating high transmit power and high gain antennas.


Title: RE: 2m amplifiers???
Post by: K0UA on January 29, 2019, 02:02:42 PM
Quote
{BTW, I personally don't consider computer-only-decoding modes (or computer-to-computer-only modes) to be actual real hams making contact....in my opinion it is computers making contact, not the human.....so, I haven't included any of the "negative signal-to-noise-ratio" / computer modes, like JT-65, JT-9, FT-8, etc., into any of my comments above....just CW, SSB (and FM)....'cuz if a human can't hear it, then a human isn't actually making that contact....just my opinion, so don't shoot me!}

Newsflash.  If you want to work meteor scatter, you WILL be working MSK144.  No one tries to work CW or SSB meteor scatter any more.  Thank God.  And while you can make meteor scatter contacts on 6 meter with 100 watts, more is much much better.  I made 25 states on MSK144, but it is all about high gain beam, and amps.  You may not consider it a contact, and you are free to think whatever you like, but IT IS.  I don't have a whole lot of interest in the mode any more as I have worked 48 states on 6 meters, some on MSK144 some on E skip, but I am not going to work Alaska or Hawaii on meteor scatter as it is not possible on that mode.

Besides people used all sorts of electronic methods back when people used to use CW.  They sent CW at super high speeds, and then tried to record it on the recieveing end and slow the tape down. A real Kludge, but I guess it sort of worked.  When MSK144 came along it was a revelation and game changer.  Time marches on, techniques improve. This is called advancing the state of the art.


Title: RE: 2m amplifiers???
Post by: W6RZ on January 29, 2019, 03:07:02 PM
Those sort of powers were used on EME when people were using CW, and also for DX work on CW on 2m such as Hawaii to California.

The Hawaii to California duct doesn't require high power. I've worked it on SSB from Silicon Valley with 100 watts to a big 2m yagi. Here's my terrain profile in that direction.

(http://www.w6rz.net/profile-hawaii.png)


Title: RE: 2m amplifiers???
Post by: KB1GMX on January 29, 2019, 03:46:41 PM
At 100W I can work Eastern MA to NJ on 2M SSB and with 50W in the mobile to
a good repeater as far as the terrain allows typically 40 to 90 miles.

You need two things a path and propagation.  If you have only one of those its
a maybe and both "usually mostly" if its near the horizon or there is obstacles.

I used to work AO27 (and others) with a pair of HTs one for UHF RX and the
other VHF TX and the VHF was a whopping 1.5W (yes one point 5).  If memory
serves the orbit of AO27 was about 480 miles and when on the horizon it would
be something over 2000 miles from me.  But nothing in the way except air.

Distance at RF is at best unlimited and at worst hard to get across the street.

Allison


Title: RE: 2m amplifiers???
Post by: KA4WJA on January 29, 2019, 03:50:25 PM

This is supposed to be a thread about 2m amps...but, actually, I did mention meteor-scatter....even though it's been 20 years since I worked a ping party, and that was on SSB....(over the years, I'd hear some guys pounding away at 25-30 wpm CW, but I could barely pick out a call, due to the fading...)

And, as for aurora....worked it quite a bit in college (in Massachusetts), but from Florida??? I've only ever seen an aurora once in my life here in Florida... :)



Now, as for my opinion about "computer-only" modes....even though I clearly stated that it was just my opinion, and I certainly don't think this is the thread to debate this....please allow me to quote what I wrote earlier, and say I stand by my opinion....  

Now, Gary, I do hope I cleared up the "mystery" of 2m amps??

As for "how much power does it take?"...well, as you can see, for most 2m communications 10 watts to 50 watts is all that is needed...with some needing 100 - 150 watts...
But, only a few (working long-haul tropo-scatter, or some still doing meteor-scatter, or the few doing moonbounce) using CW (or some SSB) have any need at all for any power over that....and as you can see, for moonbounce (CW) there's almost no such thing as "too much power"...  :)

{BTW, I personally don't consider computer-only-decoding modes (or computer-to-computer-only modes) to be actual real hams making contact....in my opinion it is computers making contact, not the human.....so, I haven't included any of the "negative signal-to-noise-ratio" / computer modes, like JT-65, JT-9, FT-8, etc., into any of my comments above....just CW, SSB (and FM)....'cuz if a human can't hear it, then a human isn't actually making that contact....just my opinion, so don't shoot me!}


73,
John,  KA4WJA

Others may differ with my opinion, and that is just fine... :)

But, to be honest, what got me to actually respond here was the comment that some used to record high-speed CW and play it back, to confirm a contact??

I've never heard of anyone recording high-speed CW and then playing it back at a slower speed, to confirm a contact...
Let alone doing that on EME or meteor-scatter???  (Heck on EME we used CW at about 10wpm....even I can copy 10wpm!!)  :)

If you have personal experience doing this, and/or could pass on the details of others that you know have done this, that would be great....seriously, I've never heard of anyone doing this...

(fyi, I do know that some on EME used to record their received signals (although I never did) in order to provide some receive information to those attempting contact and/or testing adjusting their systems....this was particularly true for the big guns who had many smaller stations attempting contact...but, I have never heard of anyone actually doing this to confirm / make a "contact"....and my experience with 2m EME goes back to the 1970's reading the "lunar Letter" and UYH's EME news....it was early 80's that I started building my station, including a DBM transverter, pre-amps, etc...(took me years)....but, in all my years I've never heard of anyone recording and playing back CW, in order to confirm a contact....}

And, as for sending CW....bugs, keyers, etc. have been with us for decades....(bugs, since before I was born), and no issue with them...and even computer-keyed CW is fine, 'cuz it is a human typing....just like RTTY, etc....

Sorry, for the ramblings....but....but, I've just never heard of anyone recording CW and playing it back, in order to confirm a contact....just doesn't seem fair to me...
But, here again, that is just my opinion!!  :)


73,
John,  KA4WJA



Title: RE: 2m amplifiers???
Post by: KG9ZTX on January 29, 2019, 04:56:19 PM
Thanks everyone I appreciate all the info. I have definitely learned something.

I’ll never do moonbounce or long range communications. But all good information to know what is possible.

I am happy with my mobile units and using repeaters.

Points out how important antennas are more then power in getting a good signal in and out of your radio for the best distance


Title: RE: 2m amplifiers???
Post by: AE0Q on January 29, 2019, 08:23:55 PM
Well, the answer was Bob Southerland, W6SAI (later, W6PO)....Bob worked for Eimac...
And, in the late 60's he designed a vhf amplifier (and a uhf amplifier) using this new tube...

Not to be picky, but Bob was W6UOV, Bill Orr was W6SAI.  I think Bill Orr wrote that article.

I DID read you entire post :-)

Glenn AE0Q


Title: RE: 2m amplifiers???
Post by: KA4WJA on January 30, 2019, 04:27:21 AM
Glenn,
Well, yep, you got me!!

Not sure if it was my memory or whether I was just distracted (I was working while I was on eham yesterday)....but whatever the case, I was wrong!!  :)  (how could I not know Bill Orr's call?? Duh!)

So, with egg on my face, I freely admit I was wrong... :(
And, thanks for correcting me!

73,
John,  KA4WJA


Title: RE: 2m amplifiers???
Post by: KA4WJA on January 30, 2019, 06:17:36 AM
Glenn, et al,

Seriously off topic....but..
But, fyi, somewhere in my files I still have my origianl W6PO / Eimac "EME Notes", as well as mimeographs of old talks/seminars on the subject mailed to me (from CSVHFS, I think?)...as well as microfiche copies of articles and papers, from Lew McCoy, Bill Orr, etc.  (that's how I learned a good bit about ham radio, as a kid/teenager)....
Wow, how life has changed...now all you need is Google and an internet connection...

73,
John,  KA4WJA


Title: RE: 2m amplifiers???
Post by: K7KBN on January 30, 2019, 10:39:32 PM

{BTW, in college (1981?) myself and classmate built a K2RIW 432mhz amp, for a NE contest station...and we got a big power supply from the EE building, and it ran 800 watts out!!  And, I think it was stil running 20 years later....}


You didn't include a power switch?  ;D ;D ;D


Title: RE: 2m amplifiers???
Post by: KB2FCV on January 31, 2019, 11:16:31 AM
I think most repeaters don't have more than 50 or 100w? Maybe less? They are usually on top of a big hill somewhere and they don't want TOO much power so that they interfere with other repeaters on top of big hills on the same frequency.  When I was more active on 2m repeaters I remember that there was another repeater in the next state on the same frequency pair that the repeater I used was on. When the repeater by me wasn't transmitting you could easily pick up the other. I think the two clubs had to work together to ensure signals wouldn't step on eachother and ensure they were using different PL inputs.

As many other stated - moonbouncers and serious VHF'ers run 1KW - 1.5KW on 2m. I have a W6PO design 8877 amp that will put out 1.5KW for 2m that I was running when I was doing moonbounce several years ago. Hoping to get that set back up again one of these days. Fun facet of the hobby to get into (pic of it on my qrz profile)


Title: RE: 2m amplifiers???
Post by: W9IQ on January 31, 2019, 01:08:15 PM
I think most repeaters don't have more than 50 or 100w? Maybe less? They are usually on top of a big hill somewhere and they don't want TOO much power so that they interfere with other repeaters on top of big hills on the same frequency.

I think two more common reasons to limit the repeater power are:

1.) To keep the transmit range reasonably within the receive range of the repeater.
2.) To keep the repeater transmitter from desensing the repeater receiver.

The latter is a hard technical boundary while the former is one of use cases.

- Glenn W9IQ


Title: RE: 2m amplifiers???
Post by: W4KVW on January 31, 2019, 01:29:55 PM
Quote
Newsflash.  If you want to work meteor scatter, you WILL be working MSK144.  No one tries to work CW or SSB meteor scatter any more.  Thank God.  And while you can make meteor scatter contacts on 6 meter with 100 watts, more is much much better.  I made 25 states on MSK144, but it is all about high gain beam, and amps.  You may not consider it a contact, and you are free to think whatever you like, but IT IS.  I don't have a whole lot of interest in the mode any more as I have worked 48 states on 6 meters, some on MSK144 some on E skip, but I am not going to work Alaska or Hawaii on meteor scatter as it is not possible on that mode.

Besides people used all sorts of electronic methods back when people used to use CW.  They sent CW at super high speeds, and then tried to record it on the recieveing end and slow the tape down. A real Kludge, but I guess it sort of worked.  When MSK144 came along it was a revelation and game changer.  Time marches on, techniques improve. This is called advancing the state of the art.

LOL,You are so WRONG. Many of us still use Phone & CW for meteor Scatter. I do NOT use any digital modes or CW on any band. I only do phone & I generally work several stations using phone when I take the time to work the Meteor Showers on both 2 & 6 Meter SSB. I have never made a digital Meteor Scatter contact in 25 years of being a Ham Operator & never will. Happy I saw your comment so I could put the Correct information out there for anyone who may be interested and like me are Phone operators.  8) ;D :D ;)

Clayton
W4KVW


Title: RE: 2m amplifiers???
Post by: K0UA on January 31, 2019, 03:23:59 PM
Go to ping jockey and see how many hams are working meteor scatter on phone or cw. Draw your own conclusions.

http://www.pingjockey.net/cgi-bin/pingtalk


Title: RE: 2m amplifiers???
Post by: W9FIB on January 31, 2019, 07:08:49 PM
I think most repeaters don't have more than 50 or 100w? Maybe less? They are usually on top of a big hill somewhere and they don't want TOO much power so that they interfere with other repeaters on top of big hills on the same frequency.

I think two more common reasons to limit the repeater power are:

1.) To keep the transmit range reasonably within the receive range of the repeater.
2.) To keep the repeater transmitter from desensing the repeater receiver.

The latter is a hard technical boundary while the former is one of use cases.

- Glenn W9IQ

Glen is correct. I am building a new repeater for our club and we capped output power at 40W for the simple reason we would talk farther than we could consistently hear with higher power. And yet we easily cover the geographical area we desire to cover. Yes, having the antenna on a tall tower on a large hill really helps in not needing big power.


Title: RE: 2m amplifiers???
Post by: W4KVW on February 12, 2019, 09:14:54 AM
Go to ping jockey and see how many hams are working meteor scatter on phone or cw. Draw your own conclusions.

http://www.pingjockey.net/cgi-bin/pingtalk

So if we don't post the contacts to a Cluster they did not happen from what you say? I have a QSL Card box with Plenty of Real QSL Cards from many of those contacts that may or may not have been posted to any Cluster. I know it takes a lot more effort & so many today are just pure LAZY & I see it is why modes such as FT8 & other digital modes are so popular. Zero effort required when they can let their computer do everything for them. I'll keep making the contacts with People & NOT computers & making a Real Human Effort & you be LAZY & let your computer make contacts for you. That is the Conclusion that I have drawn.  :P  ;D  :D

Clayton
W4KVW


Title: RE: 2m amplifiers???
Post by: KM3F on February 12, 2019, 10:44:54 AM
More example for repeaters.
Just last evening I tested the range of a new 70cm DMR/Analogue installation from my mobile. The mobile power is 35 wats, the repeater is believed to be at least 50.
I lost the repeater before I got to the county line.
On that same tower was a 2m repeater at 25 watts or less.
The mobile signal was heard quite a bit farther down range.
I used to access it from 70 miles away over mountain terrain.
Big difference.
The requirements are antenna gain, height and at last the same power as the repeater.

The antenna ERP is very important at long distances.
For example consider what the ERP of 50 wats is driving a beam at 10 db real gain.
Bottom line is you have to consider many factors, then put together a station to accomplish that goal.
On the above 70cm test, I was trying to get a feel if it was possible to access tbe70cm repeater from my home location over the mountains but it's a no go even with high beams except those rare times unreliable propagation allows it for a short times.

BTW, my experience on 222 band is that band is nearly the same performance as 2m.

To bad it's not used more.  I have logged nearly 20 repeaters of which only a few have any traffic. A pair of beams do the job.
Good luck.


Title: RE: 2m amplifiers???
Post by: K0UA on February 12, 2019, 11:19:45 AM
Go to ping jockey and see how many hams are working meteor scatter on phone or cw. Draw your own conclusions.

http://www.pingjockey.net/cgi-bin/pingtalk

So if we don't post the contacts to a Cluster they did not happen from what you say? I have a QSL Card box with Plenty of Real QSL Cards from many of those contacts that may or may not have been posted to any Cluster. I know it takes a lot more effort & so many today are just pure LAZY & I see it is why modes such as FT8 & other digital modes are so popular. Zero effort required when they can let their computer do everything for them. I'll keep making the contacts with People & NOT computers & making a Real Human Effort & you be LAZY & let your computer make contacts for you. That is the Conclusion that I have drawn.  :P  ;D  :D

Clayton
W4KVW

When was the last time you worked an actual meteor scatter contact on phone or cw? I am not talking about Es skip, I am talking about working meteor pings.  Have you ever actually worked ANY meteor scatter? Please describe your operation and equipment.