Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 ... 3 4 5 6 7 [8] 9 Next   Go Down
  Print  
Author Topic: FCC Invites Comments on Petition to Eliminate 15 dB Gain  (Read 40258 times)
KD6VXI
Member

Posts: 177




Ignore
« Reply #105 on: July 28, 2016, 05:24:23 PM »

Expert amps need to be derated by half to have acceptable IMD.

I honestly believe expert is waiting for everyone to have predistortion.....   Then their wildly exaggerated power claims can come to fruition.

Expert markets to HAMS.   because no other service could a cent their power claims and garbage spewed at those levels.

--Shane
KD6VXI
Logged
KD8MJR
Member

Posts: 5557




Ignore
« Reply #106 on: July 29, 2016, 02:21:11 PM »

Expert amps need to be derated by half to have acceptable IMD.

I honestly believe expert is waiting for everyone to have predistortion.....   Then their wildly exaggerated power claims can come to fruition.

Expert markets to HAMS.   because no other service could a cent their power claims and garbage spewed at those levels.

--Shane
KD6VXI


+1
Expert uses the same power margins that MFJ uses on their solid state amps.  That alone speaks volumes since these are not low cost amplifiers like what MFJ sells.

73s
Rob
Logged

“A lie can travel half way around the world while the truth is putting on its shoes.”  (Mark Twain)
N6YFM
Member

Posts: 824




Ignore
« Reply #107 on: July 29, 2016, 04:09:57 PM »


I'll not justify my Extra class license to you or anyone . I'll not support it with a GROL and code element nor parade my education in front of AF7XT or my "experiance" behind it .
I am appalled that an old school Extra would exhibit so little class in welcoming new amateurs to the hobby based on "I worked very hard to get my extra well over 20 years ago and it meant something when I got it " . Right now it means little or nothing if you don't teach what you learn , set an example , and...
§97.1   Basis and purpose.
(a) Recognition ...
I have no idea on your activities here so I can not and will not speak to it .
(b) Continuation ...
Hard to do if you insist on working in a vacuum .
(c) Encouragement ...
Failure in the extreme . Fortunately I need no encouragement from you or anyone . 
(d) Expansion ...
Hard to do if you consistently believe that all new amateurs are somewhat less compared to your experience . This is a welcome that I rarely experience locally or face to face .
(e) Continuation and extension of the amateur's unique ability to enhance international goodwill...
If you can not or refuse to enhance goodwill within amateur radio how can anyone expect you to do so internationally ?
§97.101 (a) Just , fail .

Last but not least , take another shot at AA4HA , Tisha Hayes , and see how many friends it gets you . One less I'm sure .

Yet another "no code CB/Extra".

AF7XT Dennis


Hi Dennis:

Well put.   It is fairly sad how many people on these forums "shoot their own team".  Our hobby has
been aging and finding trouble attracting new members young and old.  You would think all hams would
welcome ANY new hams with open arms and kind words for joining the hobby we all have in common.
Instead, the insults are epidemic.

This is my first year as a new no code general.   I am not the smartest here nor the dumbest.
I don't have 4 PHD's and I am not a high school drop-out either.
I joined for my love of radio, electronics, and hobby interest.

But I have been called some fairly colorful things over these first 6 months.
Just fascinating.
[Lucky, none of it is discouraging me in the hobby, since my day job as an engineer has taught
me to have a very thick skin :-) ]

Why do we technical people spend so much energy attacking each other?

Cheers,

Neal
Logged
KK4YDR
Member

Posts: 673




Ignore
« Reply #108 on: July 29, 2016, 10:57:12 PM »

 

Quote

Why do we technical people spend so much energy attacking each other?

Cheers,

Neal


Do not be discouraged, it takes time, but I am finding genuinely enjoyable kind hearted men and women of all ages on certain regular HF frequencies. It just takes time. 6 months is not long enough. I went through the exact same phase you described. It gets better and you learn to mash the big red IGNORE button on your HF rig called the VFO when you encounter these lids.

I as well have a no code license --- OH WHOOPTIE DOO! I have heard real code while underway in the Navy and let me tell you real CW is real and mission critical and real tactical information is passed via CW in the NAVY, not the primary comms anymore, but still required for certain people to know when crap fails cw doesn't. I am not impressed with a person ability to say hi hi over CW in HAM town. I am impressed with it's military application. It is all good and fun that a station is able to do 20 wpm but guess what... its a hobby. The Federal govt. and congress no longer seen the necessity for HAMs to learn code. Thus I am not sweating. You think we have a participation problem now with the young crowd?? Then make them learn code to get certified and you will see silent air waves as all of the older stations go SK with none to replace them. We live in the digital age with cell phones, internet, mass data consumption etc... If code is to implemented make it a separate license on its own, or an addon, make it something to be proud of and make an award for it and make it a coveted reward. But youth is not interested in what is perceived as dilapidated or archaic. We know it really isn't but code should NOT be a firewall to keep good operators off the air. The bad CB'ish ones are a problem due to the failure of the enforcement arm of the hobby to do their damn jobs. The useless FCC. They do nothing to correct the baddies on the air and we all know this as fact.

Now not to derail the thread but I really dig the concept of having an amplifer that 5 in would make 1500 out. That would be awesome.
« Last Edit: July 29, 2016, 11:08:33 PM by KK4YDR » Logged
W1BR
Member

Posts: 4189




Ignore
« Reply #109 on: July 30, 2016, 08:19:31 AM »

 
Now not to derail the thread but I really dig the concept of having an amplifer that 5 in would make 1500 out. That would be awesome.

That is close to being possible with a tetrode that is being run as a tetrode, and not a cobbled up cathode driven amplifier using a triode in GG, or a tetrode with all grids tied to ground. But, the FCC rules frown on commercial amps doing so... but a ham is still free to homebrew as he sees fit.

Pete
Logged
W9IQ
Member

Posts: 3397




Ignore
« Reply #110 on: July 30, 2016, 08:28:47 AM »

You can already homebrew an amp with >15 dB gain. The current restriction applies only to commercial amps.
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
KD6VXI
Member

Posts: 177




Ignore
« Reply #111 on: July 30, 2016, 09:46:43 AM »

3 X 4cx250s would accomplish 5 in,  1.5 out...  IMD would probably be close to the same as the expert.  I'd bet the tetrode would be cleaner.

Pair of 4cx600s would be ultra clean.

4cx1k, 4cx1.5k, they all do it.

It's all in grid driven,  and you choose the input R and the transformer ratio.   A GOOD CLEAN tetrode will run ab1 or as close to it as possible.

--Shane
KD6VXI

Logged
WA7AQH
Member

Posts: 0




Ignore
« Reply #112 on: July 30, 2016, 04:59:56 PM »

In a conversation with Elecraft at SeaPac on this topic, they seem anxious to see the limit lifted. Indicated that with very small changes on the input configuration the KPA-500 could be driven "cleanly" (their emphasis, I might add) by 10 watts with 500 out.  Just imagine a 500 watt KX2. :-)
Logged
KOP
Member

Posts: 346




Ignore
« Reply #113 on: July 30, 2016, 08:04:28 PM »

The NXP BLF 188XR is a good example of a modern device that is capable of 23.5db gain "on paper".

 "~Unfortunately, the LDMOS device data sheets provide *no* IMD spec's
for linear operation.  The only data is for CW and pulse service.  If
one is to extrapolate from similar LDMOS devices (single FET vs. two
FETs on a common die), one would need to derate to 800-900 W PEP in
order to achieve reasonable IMD levels.  That conclusion is further
corroborated by the compression spec's (actual vs. ideal output power)
which show the onset of output compression above 59 to 60 dBm (59 dBm
=> ~800W)."~ W6KAN (Thank You Tom)

Even if you were to derate the devices by half and accept the combiner losses
it still is a viable alternative to tubes with handles and 5KV 3A supplies .

Then the pendulum swings the other way and an economical 50V 100A (?) supply needs to found or built.
This has me looking at my Miller Dialarc 350 in a different light .
The initial cost of the  BLF 188XR hovers around $200 depending on the source .
What appear to be very cleanly constructed boards are available from the former East Block Europe via Ebay for less than $200.
Where you find the copper and aluminum and copper is up to you .
I strongly recommend the protection and metering boards also available from the same Ebay seller .

I suspect that from my earlier adventures with the MRF 154 that good imd figures will come at the price of derating and necessary feedback
circuitry . I understand that the current NXP/Freescale devices are much more tolerant of my ignorance but still not stupid proof .

Its an option .

I won't go into what others already have or are better able to but more than one tube option exists that has reasonable imd numbers and is capable of being driven with less than 10 watts to full legal output.

My conclusion is its a good idea for the amateur builder . I doubt its a good idea for a commercial , for retail application . Without mentioning names there already exists a manufacture that can't make -25db 3rd in a commercial , for retail sale to the US amateur market using the the previously mentioned LDMOS devices. This is sweep tube territory . How about a pallet of 2SC2879's ?

Tubes whether ceramic , metal or glass are not immune either . In some cases its a curious implementation of an otherwise surplus tube . In other cases its the tube itself .

I'm sure by now the enlightened amateur realizes that any maintenance of baseband noise is up to the individual as much as the group . Allowing a manufacturer to be their own conscience is ...

This whole view is subjective in nature and only incidentally supported by fact . This relates to the whole of my experience and is anecdotal at best and pure heresy at worst . However it is my opinion . The 15db rule , for now is a good idea not because of the long dead but still perceived CB menace but because there exist far too many imd issues with available equipment . Show me 25db gain with -40db 3rd and I'll think about it .

 

AF7XT Dennis

 
Logged

I considered a microwave oven magnetron and a 4' dish as a drone-killer. The ERP would be on the order of a hundred thousand watts or so. ~anon

November 28, 2018, 09:16:04 AM
KD6VXI
Member

Posts: 177




Ignore
« Reply #114 on: July 30, 2016, 09:07:38 PM »

As someone else pointed out.   Factory stock,  your radio is not linear with regard to IMD VS Pout.  Take a look at the 2SC2879, which was used in a lot of mid 80s to mid 90s and further rigs.   The IMD curve is a bowl!   And higher on the lower outputs.

The fix is easy,  at 10 watts pep,  pure class A.   A pair of 2879s would easily survive that.   And,  enjoy the blast furnace out the back.

--Shane
KD6VXI
Logged
W9IQ
Member

Posts: 3397




Ignore
« Reply #115 on: July 31, 2016, 05:02:08 AM »

Expert Linears apparently realised that the FCC rule making process can be a slow path so has now also filed for a temporary waiver for their 1.3K FA amp.
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
KA4KOE
Member

Posts: 357


WWW

Ignore
« Reply #116 on: August 07, 2016, 04:43:41 PM »

Where in the rules does it state is it illegal to purchase an AM broadcast transmitter? So what if one converts it to the HF bands as long as the power limits prescribed by law are followed?

Guess I'm going to jail real soon....

https://www.youtube.com/watch?v=fpnKwQVJN5A
« Last Edit: August 07, 2016, 04:52:15 PM by KA4KOE » Logged
KA4KOE
Member

Posts: 357


WWW

Ignore
« Reply #117 on: August 07, 2016, 04:51:00 PM »

Quote
Not true. You can run a huge 5 KW amplifier/appliance on 240 volts, 1 phase. Do the math...

For comparison, a typical electric range is around 8 KW.

5000w / 240V = 20.8A

Using the NEC safety factor (assuming continuous duty), 20.8 x 1.25 = 26A, give or take.

You neglected to account for the ~40% efficiency of the amp. So the amperage would be closer to 60 amps.

But then the FCC isn't considering a power limit increase.

OK, lets check the numbers......

I thought most class AB1 amplifiers were around 65% efficient, give or take. But lets take this example you quoted of 40% (very poor amplifier)....

5 KW / 0.4 = 12.5 KW

12.5 KW @ 240V, 1 phase = 52 amperes, intermittent duty. So yes, a 60 ampere, 2 pole breaker would be appropriate. However, that little thing called diversity indicates that you can still run this amplifier at your house panel no problem. Just don't cook a roast in the range at the same time to be safe. If your house electrical system was designed properly, then you should have plenty of wiggle room in your home panel...assuming of course you decide to be an outlaw and run a horribly inefficient (40%) 5 KW amplifier.
Logged
W9IQ
Member

Posts: 3397




Ignore
« Reply #118 on: August 07, 2016, 05:51:39 PM »

Phil,

My point was simply to correct your erroneous math, not to question the efficacy of running it with 100 amp service.

No question that my 40% was conservative but that is a good engineering practice. Stated amp efficiencies do not typically include the power supply or RF filter efficiencies. They often neglect filament power and startup surge current as well.

But back to the thread topic, the FCC is not proposing a power output increase. They are simply considering the concept of removing the ineffective 15 dB gain limit.

- Glenn W9IQ
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
KK5DR
Member

Posts: 631


WWW

Ignore
« Reply #119 on: August 07, 2016, 08:01:39 PM »

It's a stupid rule, ineffective. It was designed to prevent ham amps from being used on CB. It never did. CBers used ham radios to drive the ham amps, no problem.
It's just like the restriction on 10/12 meters in HF amps. That didn't work either.
Just dumb stuff. The FCC is known for its other dumb ideas too.
Logged
Pages: Prev 1 ... 3 4 5 6 7 [8] 9 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!