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Author Topic: Why doesn't the ART-13 put out 250 watts or more?  (Read 25033 times)
G3RZP
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Posts: 1278




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« Reply #15 on: December 27, 2016, 04:26:36 AM »

Interesting that a lot of amateur equipment was pressed into war service either 'as is' (HRO, AR77, SX28, and some Hammarlunds) or modified e.g. the BC610 from the Hallicrafters HT4, the RAS from the HRO. Some of the modern relatively cheap SSB transceivers with general coverage get used on occasion by the military on the basis that they are cheap enough to throw away if they break.

As far as voltage breakdown at altitude was concerned, several bits of post war radar used sealed containers with pressurisation.
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KM1H
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« Reply #16 on: December 27, 2016, 07:39:40 AM »

Peer, also consider that the extra heat for little signal gain when pushing the ART-13 above its design ratings tend to affect the PTO stability.

I run the USN ATC pre 1943 JAN designated ART-13 at about 120W with a HB supply up on 17M AM which the PTO just barely gets to. The only mods I made were to the audio stages for better fidelity and not sound like space shuttle audio.

Having heard an ART-13 dynamotor running I would never want to hear another again.

I wonder if the original pair of ART-13's are still in Enola Gay and if not do some lucky guys know what he has or has it disappeared into some basement or parts bin.

https://airandspace.si.edu/webimages/collections/full/3977cmyk.jpg
« Last Edit: December 27, 2016, 07:44:14 AM by KM1H » Logged
N8FVJ
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Posts: 888




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« Reply #17 on: December 27, 2016, 07:43:54 AM »

350 watt output AM transmitters use a 250 watt plate dissipation final tube. The ART-13 is as good as the Johnson Valiant for power output.
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KM1H
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« Reply #18 on: December 27, 2016, 07:49:55 AM »

350 watt output AM transmitters use a 250 watt plate dissipation final tube. The ART-13 is as good as the Johnson Valiant for power output.

The Valiant is a cranky and fragile ham quality TX and even then better than most in that power range......think of the various Globe Champions
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N8FVJ
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« Reply #19 on: December 28, 2016, 06:42:50 AM »

I modified the Valiant. It is solid now. Modulators are 809 tubes.
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SM0AOM
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« Reply #20 on: December 28, 2016, 07:18:24 AM »

Some of the modern relatively cheap SSB transceivers with general coverage get used on occasion by the military on the basis that they are cheap enough to throw away if they break.

As far as voltage breakdown at altitude was concerned, several bits of post war radar used sealed containers with pressurisation.

This is quite common. Many militaries use relatively high-end land-mobile and maritime SSB transceivers resulting in substantial cost savings. I estimate that you get at least 5 Codan or Barrett transceivers for the price of one Harris or Selex unit.
Some years ago, I came across a project that used the ICOM IC-706 as a "stop-gap" measure, due to slipping delivery schedules for the equipment originally specified. To the embarrasment of the original supplier, the IC-706 provided about equal RF performance, and higher reliability...

Regarding the power rating of the ART-13, they were both Power supply limited, Component rating (heating) limited and flash-over rating limited. There was a barometric sensor that limited input Power and modulation above a certain altitude. As the ART-13 could use short voltage-fed antennas on low frequency, this was a real problem.

Many present-day antenna couplers for high-performance aircraft needed to be pressurised to avoid breakdowns.
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G3RZP
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« Reply #21 on: December 29, 2016, 05:15:58 AM »


Quote
Many present-day antenna couplers for high-performance aircraft needed to be pressurised to avoid breakdowns.

Back in the early 1960s, The Marconi Company Limited had  a 'Notch Aerial Tuning Unit type 7400'. Designed to automatically tune and match to 52 ohms a notch antenna (usually in the tail fin) with an inductance of 1.3 to 1.5 microhenries, it covered 2 - 24 Mc/s at 200 watts CW, 500 watts PEP. That was in a sealed pressurised unit even then.
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AA4HA
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« Reply #22 on: January 05, 2017, 07:06:44 AM »

Having heard an ART-13 dynamotor running I would never want to hear another again.

I wonder if the original pair of ART-13's are still in Enola Gay and if not do some lucky guys know what he has or has it disappeared into some basement or parts bin.
I would suspect that the equipment that was installed in the Enola Gay (Hiroshima) or Bockscar (Nagasaki) was ever intended to be preserved "as-is". The USAAF 393rd Bombardment Squadron and the entire 509'th remained on active duty for many years following the end of the war. It would not be surprising if the radio sets had been replaced a half-dozen times over before someone thought that there was some historical reason for keeping things intact.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
N8YX
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Posts: 1365




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« Reply #23 on: January 05, 2017, 12:24:29 PM »

...The only way of saving Ham Radio is by going back to tube/discrete component sets from about 1956 to 1920.
Who's going to produce the tubes for this endeavor?

RCA is gone from the market. Ditto, Sylvania...Mullard...etc.

ETA:

" My mod'd 830 S and TS130V  'full house' with their narrow c.w. filters...

Both of these rigs are getting to "vintage" age themselves. A '130V + TS-660 + full complement of accessories for each is a challenging little package that's provided me with lots of low-power fun.
« Last Edit: January 05, 2017, 12:28:47 PM by N8YX » Logged
WA9VEZ
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« Reply #24 on: January 07, 2017, 06:22:39 PM »

The ART-13 was last produced in 1958 back when we were still using Carter dynamotors for high powered mobiles (think crystal ovened, 6/12 volt batteries, Link and Motorola's with push-pull 2E26's on silver plated lines; Twin coffins with locktal tubes.).  The 28V ART-13 was 90 watts output below 18 mhz and about 60 watts at the top end of its range. It was high level (plate and screen) AM modulated with a pair of push-pull 811's.  Manual says 90% AM modulation (and MCW for CW) but a pair of 811's in the modulator will do 100 watts of audio.  That means the plate of the 813 would go to double 1150V, or 2300V plate voltage, on audio peaks. If the modulation was linear, that would mean four times the carrier power on modulation peaks, or about twice the average plate dissipation with a good cathode emission 813. (Yeah, yeah, remember you can't go below about 150V on the plate so the screen goes above the plate voltage.)  It was a real radio that could kill you, but usually didn't.
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IW5CI
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« Reply #25 on: January 25, 2017, 06:23:08 AM »

My AN/art-13 delivers about 95W output till 20 meters.
i have an old home made power supply that delivers a conservative HV voltage.
If i increase the input voltage from 225 to 235volts to the power supply, i can reach 110W maximum and i think it's a very remarkable power for such an old trasmitter. My Johnson Valiant is just 10-20W more powerful.
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KM1H
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« Reply #26 on: January 29, 2017, 04:03:22 PM »

Quote
The ART-13 was last produced in 1958 back when we were still using Carter dynamotors for high powered mobiles (think crystal ovened, 6/12 volt batteries, Link and Motorola's with push-pull 2E26's on silver plated lines; Twin coffins with locktal tubes.).  The 28V ART-13 was 90 watts output below 18 mhz and about 60 watts at the top end of its range.

18mc is the top end of its range and with the common 1100-1300V HB PS used at least 110-120W is available on 17M with good tubes. Any more than 1300V,  and the original 811's (not the 811A) the tiny modulation transformer may bark at you.

With a Globe Champion 350 converted to a NOS 813, the PS choke removed and converted to a C only PS I could get 160W out on 10M with the driver tube changed to a 6146. Several years later the owner says it is still the same.
OTOH the ART-13 is drive limited, especially on AM which likes to be driven deep into Class C, and too much work to boost it much.

Carl
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N2DTS
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« Reply #27 on: February 02, 2017, 05:45:44 AM »

Although very well made, the modulation transformer is a bit small to push up to what an 813 can do at full power.
2000 volts and 200 ma will give about 300 watts out of a single 813.
811a's like 1200 volts zero bias, so 1200 volts is a good spot to run it at.
Should do almost 200 watts carrier output and still be very under stressed.
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KM1H
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« Reply #28 on: February 02, 2017, 08:38:17 AM »

What voltages do you run yours at?
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VK2MS
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« Reply #29 on: June 29, 2017, 06:37:13 PM »

Hi Don...just on the 19 set...apart from its UHF in the Mk2 which wasn't apparently a great success but was a great idea (if you get my drift) I think (just musing )  it may have been deliberate to limit transmissions as far as possible to the area of theatre....did they want 'enemy' 50-500 miles away to be well informed? about 'job in hand'. Ancillary 'high-power' was available (was it 4 x807's?) as you'd know very well and then antenna perhaps became more significant depending on the sought-target of that power increase. Interesting that the ZC! Mk 2 performed better than the similar transceivers 'in jungle conditions'. I had a few 19's many decades ago...they had a 'something' about them as did the 62 set. My first was a complete no 11 'air-tested' by ACE radio...the whole bit, HP supply, rack ..everything, cost me 10 pounds...a lot for me....and they delivered it to me at Mosman as they came from I think Seaforth. They 'disabled' the TX of course but I had enormous pleasure on SWL, in fact though I have had URR391, AR88D's, 348's, Commands, HRO's, AR7's, AR8's B-40's and the like some of the 'struggler' sets like the 11 ...forcing me to  concentrate on signals which were not meeting sophisticated filtering, RF, IF and 'Q' ....was a part of the fun...in fact I enjoyed my homebrew regens perhaps more than anything...I think way too much is made today of store-bought 'perfection' for Ham-licensed CB'ers who don't have the traditions. The WW11 sets bring with them a kind of spirituality when men and women and science were tested to the limit for new-order banker greed.
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