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July 15, 2019, 04:46:17 PM *
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 on: Today at 11:17:29 AM 
Started by Todd, KA1KAQ - Last post by Todd, KA1KAQ
Definitely no HOA, that's a free choice and no brainer. Zombies are all in the city or on I-95, staring at their i-phones. They're easy to spot on the streets, arm outstretched, staggering along running into others as they stare down at their smartness.

400A service split between two 200A panels. There is a very small workshop out back, and the house is pretty good sized. I'm planning on two or three 240v outlets, a couple 20-30A, single 120v outlets for the transmitters, plus a couple 20A for everything else in the station.

Gotta get moved first.

 on: Yesterday at 11:17:45 PM 
Started by W4AMV - Last post by W4AMV
Looking for a 3 or 4 section ganged 360 pF variable C for a transmitter build.
Power level just 200 W

Tnx, Alan W4AMV

 on: Yesterday at 08:07:03 PM 
Started by Steve - K4HX - Last post by Opcom
A confessed cat killer to boot.

 on: Yesterday at 07:49:50 PM 
Started by Todd, KA1KAQ - Last post by Opcom
Wow that's tops! I thought you were going to say there is no HOA and no zombies! 

Is that a 400A service? Did the owner have a machine shop in the garage or did you get a nice big house?
I have never seen that in a house. Seen it in a lab a few times, where each workbench had its own receptacle and breaker.

Haha we await what may get built.

 on: Yesterday at 07:14:05 PM 
Started by KJ6NKX - Last post by KJ6NKX
I'm on the hunt for a schematic for the Gates Stereo Yard board.
This model is pretty rare, and the schematic is apparently even rarer...

 on: Yesterday at 05:35:27 PM 
Started by KF4IZE - Last post by KF4IZE
I'm looking for a functional multi-meter (M2) for my Henry 2K amplifier. It is the tear-drop style meter and measures grid current and plate voltage. Does not have to be in mint condition, only working. Please send shipped cost to zip code 28304. Thanks so much in advance. 73 de KF4IZE

 on: Yesterday at 04:39:41 PM 
Started by ka4lbi - Last post by ka4lbi
Hi Gang, I am in need of two or more of the switch I have in the attached photo... Please reply with the price including shipping and the quantity that is available.... Respectfully KA4LBI

 on: Yesterday at 04:34:53 PM 
Started by Opcom - Last post by Opcom
Do you have the filter design available?

Here is a nice Chinese pcb manufacturing video from PCBWay.

 on: Yesterday at 07:03:31 AM 
Started by SM6OID - Last post by SM6OID

I'd like to share my AM results so far with you.

OK I have two BC-696A that originates from the Danish Air Force.
One of them is "highly rebuilt", new cables and components, including removing the roller inductor.
The other one is close to stock, only the antenna relay has been removed AND it has a modified frequency range, 2.8-3.6 MHz, it is said by a former Danish AF Tech that is was used for their communication with a station on Greenland on 2.8xx MHz.

For those of you not familiar with these nice set, use google!
But in short, it's a MOPA configuration comprising two 1625 parallel finals, about 40 W CW nominal output.
The ATA (early Navy versions) and SCR-274-N are screen grid modulated while the ARC-5 series are plate modulated.

So, here we go...
First CW, with approx. 200 V on the MO plate and 800 V on PA plate, screen grids via a resistor of 27 k from 800 V.
Result is approx. 100 W out, it sounds ok, its a MOPA so the tone is "nice and round".
The voltages are stabilized.
So, then how to modulate?

Looked around and with in my reach I found an singe ended output transformer.
Connected the PA screens to 200 V via the transformer "primary" and the "secondary" now became primary and hooked up to a AF generator.
Transmitter was tuned to max smoke CW and now I had around 40+ W carrier with 200 V on the PA screens.
Turned up the AF generator and I began to see a modulated envelope!
Set the modulation as high as "practically possible", about 85-ish%.
Readjusted the transmitter loading (external tuner) and screen grid voltage a little, the envelope looked OK, trapezoid pattern also indicated the it was entirely usable around 80-85%!

Then I hooked up an old radio from mid -50's as audio source, music sounded OK too.
Yesterday I made an audio test over the air with another ham 50 ish miles away, 40+ W carrier and probably 75-80% modulation to minimize the risk of distortion.
This time I had a car audio amp from a Saab 9000 as "mod amp"
Played Dream a little dream of me, with Mama Cass.
The "listeners report" I received was very positive!
Next step is to feed my own voice and make some QSO's.

In the future, a power supply needs to be constructed, the current set up is terribly bulky and occupies too much space.

Future also involves modulating my "brand spanking new" ATA (5.3-7.0 MHz) that will stretch well in to the lower part of 40 m phone. Had it on the air CW, making a stout 100+ W with 800 V on PA plates.

Attached a picture, the thing that looks like a toaster is the BC-696A, on top of the scope the modulation amplifier can be seen, the PS for MO and screen grid, modulation transformer can not be seen.

Needless (?) to say, I'd like to lay my hands on the original modulator, both the BC-456B and the MD-7/ARC-5, but it appears that they are about as rare as hens teeth...

 on: July 13, 2019, 04:24:11 PM 
Started by Jim, W5JO - Last post by Jim, W5JO
For west coast people there are a few xformer people in the Los Angeles area as well. 

If you can, put their contact information on so I can make a note.  I live in the middle of the country and shipping is about the same either way. 

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