This was via e-mail, I am on their mailing list. I don't think it was a fake.

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

People must understand that the power distribution in speech is not very efficient. Thus speech processors. They do several things but all are to the end of modifying power distribution to make it more efficient in power limited transmission systems. Note that as a rule of thumb the ratio of peak to average in male speech is about 10db. If a transmitter is set to pass peaks without distortion its average output will be very low. A processor reduces the ratio of peak to average in various ways and also modifies the spectral distribution in the speech to accentuate the parts that contribute to intelligibility and articulation. An ALC is really a sort of peak limiter to reduce drive when it will drive the amplifier into distortion. Most ALC systems are fairly simple so an external processor is often more effective. With an external processor the ALC can be almost inactive but will provide a safety factor.
The idea is to increase average power to overcome noise. This also applies to the modification of the speech spectrum. Since low frequencies contribute the most to speech power but relatively little to articulation it is common to limit low frequency response and enhance high frequency response since the highs contribute most to it. However, the effect of combined spectrum shaping and amplitude limiting is not simple so some care must be applied in deciding what exactly to do.
There is a perfectly enormous amount of literature on speech processing (and music processing) in the technical literature. Bell Labs has research going back a century, worth doing some reading.

--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

On 2024-04-25 14:50, Richard Knoppow wrote:

I just got an e-mail from MFJ announcing they are going out of
business. Will continue to sell until they are out of stock and will
offer repair services in the future. Applies to all their associated
companies.

Wow. This is serious bad news. Interesting, their website has no hint of it.

- Jerry, KF6VB

I just got an e-mail from MFJ announcing they are going out of business. Will continue to sell until they are out of stock and will offer repair services in the future. Applies to all their associated companies.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998

Yeah, you don't want to do that. We have enough trouble these days with dirty signals on the air. Don't add to it. Get an inline processor, SP75 or equivalent.

73

-Jim
NU0C

On Thu, 25 Apr 2024 08:58:25 -0500
"Joe WB9SBD via groups.io" <nss@...> wrote:

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

On 4/25/2024 7:08 AM, Jim VE7RF wrote:

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.

--

73

-Jim
NU0C

开云体育

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.??

开云体育

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