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Thanks Jim,
But I remember someone looking at the signal on a Heathkit station monitor and while it was a fat Christmas tree it was far from a fully filled as you say green bar.

I wonder if anyone can do some scope image grabs of shorted vs open,

Joe WB9SBD

To getter the tubes,? you can use the lower B+ position, apply a bit of drive ( with amp into a DL), then tweak the tune cap off resonance a bit.? ?That's from W8JI.?

Another method is to use a small lab supply, with positive terminal to chassis...and negative to cathode...and apply some vdc.? ?That will bias the tubes on....and plate current can be dialed up to anything you want.? ?This is with amp keyed on, NO drive applied...and drawing idle current.? ?With the small lab supply,? you can dial up any amount of idle current you want.? Again, use the lower B+ setting.? ?This method will work? with B+ as low as 900 vdc.?

On a good eimac 3-500Z, they will hi-pot test 16 kv from anode to grid...... and 5 kv from grid to cathode.?

?

On the chinese 3-500Z's, they hi pot test 1 kv? between grid and cathode, normal for chinese 3-500Z's.? The chinese 3-500Z's also have a lot higher grid to cathode C? vs an Eimac.? The chinese tubes have the grid a lot closer to the cathode vs an eimac.? Grid to cathode shorts typ show up when the? cathode is lit.... and results in negative grid current on idle. ( on RX), and tube biased off.?

On my 4 x L4B's, they all use 3 x 15 ohm resistors in parallel for the suppressor assy ( IE: 5 ohms in total), then wrapped with 2 turns of 3/8" wide silver plated copper strap.? ( 15 ohm carbon comp, 2 watt resistors).? Brown-Green-Black.?

The 3 x resistors look like brand new on all 8 x tubes.? ?Now figure that one out.?

With no reading glasses on, I was sure the diagram showed 150 ohms each....and 3 in parallel. = 50 ohms.? But alas, the? 'zero' was actually the ohm symbol !? Then saw the Brown-Green-Black color bands.?

With the? ALC jack shorted out, the mic gain became the RF clipping level control.? IF? you wanted some more talk power for some pile up, it worked good.?

It was done all the time back then. Just a spst toggle to short out the? ALC jack.? ?Then it looked like a solid green bar on the scope, instead of the typ 'xmas tree' pattern.?

Funny thing was, nobody bitched abt imd / splatter...go figure.?

Some folks in W6 land told me they pulled out one of the tubes, then cut off one of the pins, to do the same thing.?

Essentially, you turned it into an rf clipper, albeit, with no filter to clean up out of band imd products. A real RF clipper would have the 2nd filter. ( like the magnum 6 /? DX engineering RF clippers).?

The Vomax was just a split band audio clipper, with a filter for each of the 3 x bands.? Then the filtered ( and clipped) 3 x bands were? re-combined.??

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Hello Lyndon.

WB4HFN page can be of help. Also GW4ALG used to have a page on homebrew versions of the modules you have. Those old pages can be seen here:


This page shows you how to make each of the other band modules:


This page shows you the WARC band modules:


?The WB4HFN page at:

has a homebrew Aux7.

Jim Shorney's article:
/g/DRAKE-RADIO/files/TR-7%20Better%20Allband%20Transmit%20Mod.pdf
or

talks about how to "general coverage" the TR7 for both transmit and receive without the Aux7 and associated modules.

If you do want to make modules for the Aux7 then as someone else suggested, buy a supply of 1N4148 diodes.? The 14 pin DIP headers will be harder to find and expensive.

Another WB4HFN page that shows the truth table for those modules and where the cathodes of the 1N4148's need to go to make up your RTM7 band modules:


Good luck.

Jim Pruitt
WA7DUY

When I engage the RIT on my TR-7 it adds 5kc to the receive frequency & adjusting the RIT pot has no impact. Wondering if anyone else has run into this or has a suggestion on what to look for?

thanks!
Shawn
kj7mx

I think they are actually plated copper.


On Wed, 24 Apr 2024 20:02:39 -0700
"K6OXN Bob via groups.io" <bobk6oxn@...> wrote:

I don't have a nanoVna but the coil is the original .5 inch twisted aluminum original in the L7

--

73

-Jim
NU0C

I don't have a nanoVna but the coil is the original .5 inch twisted aluminum original in the L7

Same here when I had an R7 with an AUX-7 board.

Here's a not so great pic of one I made 40 years ago but it doesn't look
quite right based on the info in the Module programming chart on page 4
of the manual.? Not my greatest work, but it gives you an idea of how to
make them.

73

Stan
KM4HQE

On 2024-04-24 18:17, Jim Shorney wrote:

Yup, DIP headers and 4148s are the way to go. This hack is years old.
I did it in the late 80s and it had been around a while by then. :)

*** I did it too. I got the appropriate Molex connectors in Ebay, and wired
up essentially a complete Aux7 on a piece of perfboard. Well, except for the
crystal oscillators.

- Jerry, KF6VB

Yup, DIP headers and 4148s are the way to go. This hack is years
old. I did it in the late 80s and it had been around a while by
then. :)

So I just went diode shopping at Newark. They were giving
away 4148s! I just bought a lifetime supply (1000) for
twelve bucks. I just wish they sold caps that cheap ...

--lyndon

Yup, DIP headers and 4148s are the way to go. This hack is years old. I did it in the late 80s and it had been around a while by then. :)

73

-Jim
NU0C

On Thu, 25 Apr 2024 00:33:43 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:

I’ve used 1N4148’s on DIP headers. 1N914’s work just as well. Somewhere on Ron’s page are the diagrams for setting the bands.

73,

Steve Wedge, W1ES/4

Time flies like an arrow. Fruit flies like a banana.

Sent from [Proton Mail]() for iOS

On Wed, Apr 24, 2024 at 20:15, Lyndon VE7TFX <[lyndon@...](mailto:On Wed, Apr 24, 2024 at 20:15, Lyndon VE7TFX <<a href=)> wrote:

From poking around the band modules on the AUX-7 I acquired,
they just seem to be diodes connecting pin 1 to everything else,
right? Is there any reason I can't just roll my own with 1N4001s
or something similar?

The two modules on the board I have appear to be TI parts,
labelled BC1206. I have searched high and low but I can't
find a data sheet, or any reference at all, to a TI part
bearing that number. Anybody have an idea what those might
be?

Cheers,

--lyndon

P.S. I have two band modules covering 0-1MHz I would be willing
to swap for some WARC coverage :-)

It could. Really the coil should be shorting out the resistors at HF frequencies so very little RF will pass through them. You don't have that Nichrome snake oil that was going around a few years ago, do you?

I would check your resistors with a NanoVNA to make sure they are non-inductive. Not all are really.

73

-Jim
NU0C

On Wed, 24 Apr 2024 17:31:08 -0700
"K6OXN Bob via groups.io" <bobk6oxn@...> wrote:

Quick and maybe easy question, Could a cold or poor solder joint on the Parasitic Resistors where they attach to the so called coil of the Plate connector cause my problems with the hot resistors?

73? Bob

I've used 1N4148s on DIP headers. 1N914s work just as well.

My brain meant to type 4148, but my fingers had other ideas ;-)
My plan of attack is also to use headers.

Somewhere on Ron's page are the diagrams for setting the bands.

I have the AUX-7 documentation so I'm good to go.

Thanks for the confirmation.

--lyndon

Quick and maybe easy question, Could a cold or poor solder joint on the Parasitic Resistors where they attach to the so called coil of the Plate connector cause my problems with the hot resistors?

73? Bob

From poking around the band modules on the AUX-7 I acquired,
they just seem to be diodes connecting pin 1 to everything else,
right? Is there any reason I can't just roll my own with 1N4001s
or something similar?

The two modules on the board I have appear to be TI parts,
labelled BC1206. I have searched high and low but I can't
find a data sheet, or any reference at all, to a TI part
bearing that number. Anybody have an idea what those might
be?

Cheers,

--lyndon

P.S. I have two band modules covering 0-1MHz I would be willing
to swap for some WARC coverage :-)

The resistors I replaced were 2 watt 47 ohm carbon composition resistors just like the one's that exploded. I am still perplexed as to why these would run so hot as to burn up. All items in that circuit checkout perfect. I realize that 1000pf instead of 1520pf ceramic capacitors shouldn't make that much difference.? The Door knob are rated at 7.5kv so should be good. I did find a poor solder joint on one of the parasitic resistors but it had good mechanical connection.? Have repaired that.? I will look into some of the other type of resistors.? Thanks

73? Bob