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Using an SB220 on AM




 
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WA3MJY
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« Reply #25 on: August 20, 2009, 09:14:03 PM »

WOW!!! I didn't know that I would cause such a stir when I asked the question, LOL. As I said before, you guys have given me much to consider and I really do value all of what has been said. The first modification I will make to the amplifier is change the cooling as it appears that everyone agrees this is inadequate. The second will be adding the stand-by switch. 
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ke7trp
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« Reply #26 on: August 21, 2009, 12:20:10 AM »

This is the way we discuss. Nobody is mad at anyone.  At least I hope..  Smiley


Clark
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Steve - WB3HUZ
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« Reply #27 on: August 21, 2009, 12:24:45 AM »

LOL. We skipped school on the days they had sensitivity training.
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KD6VXI
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« Reply #28 on: August 21, 2009, 12:26:04 AM »

This is the way we discuss. Nobody is mad at anyone.  At least I hope..  Smiley


Clark

I LOVE the people that can't tell the difference between a discussion and an argument.

My ex girlfriend being one of them.


--Shane
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N2DTS
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« Reply #29 on: August 21, 2009, 08:49:20 AM »

I never had an amplifier, and would not think of buying one, as it seems (to me) that you spend a lot of money in electricity in one for little power output.

Maybe if I had a flex radio, that would likely be cool, but to put a ranger or some such into a big amplifier and have it generate loads of heat to get 200 watts out seems kind of silly to me.

Brett


 
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The Slab Bacon
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« Reply #30 on: August 21, 2009, 08:53:46 AM »


LOL. We skipped school on the days they had sensitivity training.


Yes...........It's fun!! Sometimes its fun to put one across someones bow and give them a good poke in the ribs. If they cry and run away it's no fun. When I give them a good poke in the ribs, I full well EXPECT one in return! thats half of the fun of it. One needs to be thick skinned and have a sense of humor.  Grin  Grin

Ifn you cant run with the big dogs, stay the hell on the porch Shocked Shocked Screw a bunch of sensitivity training, that stuff is for pansies! Besides, everyone enjoys watching a good fight.

you just gotta learn to disagree agreeably Grin

                                                     The Slab Bacon

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KM1H
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« Reply #31 on: August 21, 2009, 09:36:49 AM »

Having been born and raised in Brooklyn, then LI and next into the Navy, sensitivity training would have been a recipe to disaster.

Go to any New England selectmans/city council or Town Meeting if you want to hear fireworks. Don Rickles would be proud Grin

The current crop of castrated males in this country makes me puke.

Carl
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K3ZS
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« Reply #32 on: August 21, 2009, 10:02:06 AM »

At the risk of commenting on the actual subject, my experience with using older linear amps on AM has been they work fine as long as they are tuned to provide the peak power output on AM that matches their ratings on SSB.    If you don't load them heavily enough you can get a higher carrier power but the peaks will be clipped.    I find that the sweet spot for AM is to tune the amp for max power output then increase the loading until the power drops to about 175W to 200W of carrier on the output.   This should give you the best sounding audio peaking around 700-800 W PEP.
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Steve - WB3HUZ
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« Reply #33 on: August 21, 2009, 11:55:08 AM »

If you do the math, there is very little difference in the actual AC power input for given RF power output when comparing a plate modulated rig and a low level rig driving a linear. Sure the RF final is less efficient, but there is no high level modulator (nothing more than a linear amp that is now more efficient than an RF linear amp).
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WA1GFZ
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« Reply #34 on: August 21, 2009, 12:01:09 PM »

HUZ,
Also there is a lot less hardware to break down

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w1vtp
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« Reply #35 on: August 21, 2009, 12:40:28 PM »

I never had an amplifier, and would not think of buying one, as it seems (to me) that you spend a lot of money in electricity in one for little power output.

Maybe if I had a flex radio, that would likely be cool, but to put a ranger or some such into a big amplifier and have it generate loads of heat to get 200 watts out seems kind of silly to me.

Brett

( Bolded emphasis in quote mine)

Yup, Brett.  That's why I presently use a Courier on my present Flex setup and plan going to legal limit with an amplifier upgrade some day (soon).  But, that aside, the stuff you have built has inspired me to buy stock in the 4D32 and either go your route of 3 x 4D32s or an 813 OR a Russian GU-48.  Why put one's eggs in one basket. Smiley

Al
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Steve - WB3HUZ
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« Reply #36 on: August 21, 2009, 12:46:59 PM »

Yep, no big mod transformer, no power sucking audio driver circuitry, etc.  Avoiding the linear amp option made sense back in the day when there was a limit on power input. No longer.


HUZ,
Also there is a lot less hardware to break down


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WD8BIL
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« Reply #37 on: August 21, 2009, 01:04:58 PM »

Quote
Cherry plates, .....

Cherry plates on a 3-500Z is piss weak.
They ain't working till you get that orange near white!!!
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WD8BIL
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« Reply #38 on: August 21, 2009, 01:09:47 PM »

Quote
At the risk of commenting on the actual subject, my experience with using older linear amps on AM has been they work fine as long as they are tuned to provide the peak power output on AM that matches their ratings on SSB.    If you don't load them heavily enough you can get a higher carrier power but the peaks will be clipped.    I find that the sweet spot for AM is to tune the amp for max power output then increase the loading until the power drops to about 175W to 200W of carrier on the output.   This should give you the best sounding audio peaking around 700-800 W PEP.

Good point. I use a 1kc tone to tune the Viking 1 driving a pair of 8874s in AB2.
The scope tells the story. Nice round peaks at 1499 W PEP! And you're correct. The loading is the key.
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KD6VXI
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« Reply #39 on: August 21, 2009, 06:14:57 PM »

Quote
Cherry plates, .....

Cherry plates on a 3-500Z is piss weak.
They ain't working till you get that orange near white!!!

And if I'm not gettin my 4CX250R's to pop, then I'm still on the LV tap, at 2Kv...

2800 volts makes them REALLY come alive, although you BETTER have the loading right Smiley

Hence the reason, I refer to the 250 as the "Popcorn" tube!

--Shane
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N2DTS
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« Reply #40 on: August 21, 2009, 06:32:34 PM »

Ok, well, how much power can you get out on 110 vac?
The pair of 813's runs 600 watts of carrier out, 2400 watts pep, on 110vac.

Ok, the modulator is on another 110vac circuit, but the lights dont dim or anything...

What amp could run 600 watts (or 700 watts) carrier out for 20 minute old buzard transmissions, and on 110vac?

Brett
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WA1GFZ
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« Reply #41 on: August 21, 2009, 06:34:01 PM »

All about tank Q Bud, so it is loaded properly
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WA1GFZ
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« Reply #42 on: August 21, 2009, 06:37:29 PM »

110VAC depends on the conductor and breaker size not to mention the plate iron.
Normal 20 amp circuit  would do 2 KW plate modulated or linear amplified.
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KM1H
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« Reply #43 on: August 21, 2009, 09:00:35 PM »

Ok, well, how much power can you get out on 110 vac?
The pair of 813's runs 600 watts of carrier out, 2400 watts pep, on 110vac.

Ok, the modulator is on another 110vac circuit, but the lights dont dim or anything...

What amp could run 600 watts (or 700 watts) carrier out for 20 minute old buzard transmissions, and on 110vac?

Brett


On a 20A line anything with 800-1000W Pd tubes and a full flow air system. That might include the old Henry's, Heath Chippewa, Johnson T Bolt, Hallicrafters HT-33B and a few others. I think it was BTI that had a 3-1000Z amp in the 60's.

If building Id use 4-400A's as IMO they are a bit underated for Pd and cheap. Use 3-4 if you want to lock the mike and try to break the OB record.

If you got the money there are 8877 medical pulls (actually the pulse 3CPX1500A7 is used) or if you want a real loafer the YC-156 is a bargain in the pull market. Both are in the $300-400 range for very good ones.

Carl
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ke7trp
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« Reply #44 on: August 21, 2009, 09:05:04 PM »

Four 4-400s sounds like a real nice amp..

I had a single 4-1000 amp with Vac variables, 2 amp PWD transformer. With 7000 volts on the plate it really put out power. The 4-1000 pulse tube I had was a screamer. I wish I still had it.. Like a dope, I sold it off thinking I would never need that much power.  I am sure It would have ran full legal AM all night.

Clark
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WD8BIL
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« Reply #45 on: August 21, 2009, 10:28:06 PM »

I got a 4CX250B in the Viking 1, Shane.

Well, I did. Just last week I conduction cooled it with a 8560.
Same tube, different cooling. Works great.
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Ed-VA3ES
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« Reply #46 on: August 21, 2009, 11:01:19 PM »

Shane, I have some  serious questions for you:

   Yeah, we have BE's in the amateur radio ranks.  We also have them in the CB radio world.  I know of 3 BE's that run 15kw plus, 2 FCC engineers (one running my amp) that operate on 27.025, etc., etc., etc. 
What  fascinates these people about CB, and specifically the "Superbowl" channel?    One would naturally think that they might be attracted to amateur radio?   After their so-called  "competition",  what attracts them?   What fascinates them?

[...]  Dennis O. can run circles around most "Broadcast Engineers" that I've had the pleasure of meeting, but refuses to use amateur radio.  He now works at Motorola.  Does it mean ANYTHING that he works on CBs to supplant his income?
Why  does he refuse to opeate on amateur radio?   As above,  what attracts him to CB,   what is it that fascinates him?

Frankly, I just don't get it.   To me, CB/freeband, etc.  is  a dead end.
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N3DRB The Derb
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« Reply #47 on: August 21, 2009, 11:12:11 PM »

they like it better.  Shocked

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Ed-VA3ES
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« Reply #48 on: August 21, 2009, 11:15:41 PM »

they like it better.  Shocked

OK, but why?  What's the attraction?   
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KD6VXI
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« Reply #49 on: August 22, 2009, 12:52:14 AM »

Shane, I have some  serious questions for you:

   Yeah, we have BE's in the amateur radio ranks.  We also have them in the CB radio world.  I know of 3 BE's that run 15kw plus, 2 FCC engineers (one running my amp) that operate on 27.025, etc., etc., etc. 
What  fascinates these people about CB, and specifically the "Superbowl" channel?    One would naturally think that they might be attracted to amateur radio?   After their so-called  "competition",  what attracts them?   What fascinates them?

[...]  Dennis O. can run circles around most "Broadcast Engineers" that I've had the pleasure of meeting, but refuses to use amateur radio.  He now works at Motorola.  Does it mean ANYTHING that he works on CBs to supplant his income?
Why  does he refuse to opeate on amateur radio?   As above,  what attracts him to CB,   what is it that fascinates him?

Frankly, I just don't get it.   To me, CB/freeband, etc.  is  a dead end.

1.  Generally, the people on 'the superbowl' are a lot less stringent about who they "accept".  If you pay the price of admission, your admitted into the "Club".  On amateur radio, it just isn't that way.  I'm looked down upon as being "no code".  So what, I passed novice through extra in one sitting, and gave shit about the code.  15 years or so later, soon as they dropped it, and I got HF equipment, I came back.

I enjoy both services.  So do a LOT of amateur operators!  I know of at least one top ten finisher of most contests that runs 27.025.  Discretion is the better part of valor, hence the reason I actually KNOW who the person is.  If they where known in the amateur ranks, they would be looked down upon.

Dennis let his call expire and gave up on amateur because of the same reasons.  WHY?  Why get a ticket to be part of some elitist club.

I ran in to the same problem asking for help here.  I put a name out, and all of a sudden, 3 people where jumping all over me, asking for call signs, etc.  I got news for you, YOU DON'T NEED  A CALLSIGN TO HAVE A WORKING TRANSMITTER, YOU DON'T NEED  A CALLSIGN TO GET HELP, NOR DO YOU NEED A CALLSIGN TO PURCHASE JUNK FROM A HAMFEST with the intention of fixing it up and putting it on a shelf.  BUT, I only got 1 (ONE) response that actually helped.  I did spend a week fighting off the (assholes) guys who wanted to trace down who I was talking about based upon clues I gave, etc., etc., etc.  Funny, the person I was helping actually IS ON THIS REFLECTOR NOW!  BUT, he wouldn't have been, had this reflector been the ONLY way he was introduced to amatuer radio.  Upon going to his house, his attitude was "those people suck!", since they wouldn't help out since he WOULDN'T provide a proper call.  What a bunch of crap, hiding behind the "I can't help someone I know is doing something illegal" lingo, when in actuality, it was because they didn't want to help someone who <<might>> be a CB operator.

CB radio has it's place.  I don't know of anywhere other than 2 meters that you can pretty much just buy your equipment and be accepted.  And that isn't even a given on 2 or 11 meters.

Just my take.  I enjoy all radio services, have radios for all services, and think that people that bash one radio service over another are nothing more than lids.  PERIOD.

As to what drives them to do what they do?  What drives ANY of the consistent top 10 contest finishers to do what they do?

Hope that didn't go over the top.

--Shane
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