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SoundMods
PostPosted: June 18th, 2025, 1:46 pm 
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Joined: July 24th, 2015, 4:17 pm
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Location: Parkville, Maryland
Hey all. I own a Hickok 6000A Mutual Conductance tube tester and as your learned from Part 1 that I posted yesterday – I was able to replace its vacuum tubes with solid-state modules.

Since my power amplifiers use 300B power triodes as pre-drivers and 845 power triodes for the outputs I could not test either tube-type with my Hickok tester. I do have a basic emissions tester that accommodated the 300B and using the Jumbo 4-pin to UX-4 adapter I could test for emission level. But what if the tube failed without the grid functioning? The emission tester is of no value at all. It typically connects the grid-to-the-plate to test for plate current. Tests good but it is not functional in your amplifier and you'll not know the reason why. Hell -- it is only triode - -what can go wrong? Besides you might want put together matched pairs and a mutual conductance tester works like the tube is in a working circuit.

As I noted in part 1 – need is the mother of invention. I fabricated a UX-4 4-pin to 8-pin octal adapter to use with my Hickok. I did find a manufactured adapter, but the UX-4 socket was “junk” as the socket was too tight for the average 300B or my Jumbo adapter’s UX-4 jack. To add insult to injury the “store-bought” pin-connections did not coincide with any known tubes that the Hickok was designed for. Except for a company in the U.K. that offered one -- but they couldn’t take orders because of a flooding disaster they were dealing with. I didn’t want to wait.

The adapter I constructed is an easy task for any DIY’er on this BLOG that has the scratch-building “chops.” The attached photo shows the component parts used except for the solid-conductor wire, paint, and epoxy. You can either use the EMT connector full length, or as I did, or cut it down (preferred). The 4-pin socket and 8-pin octal plug fit into the EMT connector perfectly. The EMT connector can be obtained at any Home Depot and the socket and plug is available on eBay. Here are the links:

https://www.ebay.com/itm/195386515290

https://www.ebay.com/itm/195861332924

The Jumbo adapter is also available on eBay:

https://www.ebay.com/itm/355472580407

The <*.pdf> file attached is the final solution to enable testing 300Bs and 845s with the special settings that I determined for use on the Hickok 6000A. For those who wish to test 45s, or 2A3s, or 211s you can easily dial-in their requirements and establish your own special settings. What you will need to enable testing those tubes is right here in this presentation.

Just a note – this presentation is for private use only by the members of this group and not available for publishing without my express written permission.


Attachments:
Octal Adapter Parts.JPG
Octal Adapter Parts.JPG [ 2.34 MiB | Viewed 315 times ]
Jumbo-UX-4 Adapter.jpg
Jumbo-UX-4 Adapter.jpg [ 1.03 MiB | Viewed 315 times ]
Hickok 300B&845 testing.pdf [343.53 KiB]
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tomp
PostPosted: June 18th, 2025, 2:11 pm 
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Walt comes through again. Great job.
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SoundMods
PostPosted: June 18th, 2025, 4:58 pm 
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Joined: July 24th, 2015, 4:17 pm
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Location: Parkville, Maryland
tomp wrote:
Walt comes through again. Great job.

Thanks! :obscene-drinkingcheers:

Of course one can always buy the Amplitrex AT1000 Vacuum-Tube Tester for $1.795 plus tax and shipping costs.

Since I don't have "deep pockets" I spent my waking hours coming up with a way to test those triodes with my Hickok.

I tested multiple tubes that I have in stock (yes -- I am a rabid audiophile) and got the expected results.

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