Can someone tell me or a picture would help better? Where C100 is?? Should be a .22 uf?

Skip

Take a look on page 2-7 (two times in the PDF) where you might find what a are looking for.

Karl, DK7AL

On 2024-04-08 09:39, Gary Follett wrote:

You’d need to cross-correlate the data to Yaesu but there is band
data, at logic level, on the bandswitch.

*** I'll need to look into that. Could possibly do it with a diode
matrix.

- Jerry, KF6VB

You’d need to cross-correlate the data to Yaesu but there is band data, at logic level, on the bandswitch.

Gary

W0DVN

On 2024-04-08 08:53, Jim Shorney wrote:

Attached, version 2 digital control board. They changed to a PROM for
the default band logic.

Interesting. I wonder how hard it would be to get band data out of the radio?
I have a homebrew linear that has no bandswitch - it just follows the exciter via
Yaesu band data.

- Jerry, KF6VB

Attached, version 2 digital control board. They changed to a PROM for the default band logic.

73

-Jim
NU0C

On Mon, 08 Apr 2024 06:33:30 -0700
Fran?ois F1FPG via groups.io <fra.gab@...> wrote:

I would like to get copies TR7 schematics ( not 1976 realise but the last 1982).? Does anyone know if such exist somewhere? Haven't found anything online as yet.
last TR7 ( SN 9XXX) and TR7A(10XXX)? are not realy different but without schematics troobleshoting is not easy!
sorry for my poor english or américan? but i'm sure you will understand my request!
best 73" Fran?ois F1FPG

This may be the latest one I have in PDF. Unfortunately the people who scan these tend to leave out the page that has the publication date. if the attachment does not come through you should be able to find it on the internet.

The major changes were to the Predriver, 2nd IF/Audio board and the Digital Control board. The new version of the Digital Control board is not in this manual but I may have it as a separate file. There were also some changes to the 2nd Mixer board but I think the later revisions are in most rigs except the very oldest and most of the changes are in the published manuals. I do have most of the 2nd Mixer changes documented, as well as some of the known 2nd IF/Audio changes. There are a couple of resistor changes on the PBT/Ref board to support the version 2 2nd IF/Audio board but otherwise it seems essentially unchanged. The TR-4310 service manual has some newer info if you can find one.

I think my paper reproduction has some later info but I would have to check it. I don't recall who I purchased it from.

73

-Jim
NU0C



On Mon, 08 Apr 2024 06:33:30 -0700
Fran?ois F1FPG via groups.io <fra.gab@...> wrote:

I would like to get copies TR7 schematics ( not 1976 realise but the last 1982).? Does anyone know if such exist somewhere? Haven't found anything online as yet.
last TR7 ( SN 9XXX) and TR7A(10XXX)? are not realy different but without schematics troobleshoting is not easy!
sorry for my poor english or américan? but i'm sure you will understand my request!
best 73" Fran?ois F1FPG

开云体育

MN2700 SOLD
Thank you everyone for looking.

Kind of the opposite of what you would do to avoid orange peel.

- Jerry

You can amplify a hammered-spackled finish by painting outside in the sun,

or I suppose by using a heat gun, to speed-up the drying of the paint.

Someone told me that and it, in my experience, worked.

Ah. That makes sense. The cabinet looks quite nice, BTW.

- Jerry, KF6VB

You use the drill bit to make the hole on the nozzle larger.? That way
is sprays large drops, for the lack of a better word, of paint. One
holds the can about 2 ft away when spraying.

73

Stan
KM4HQE

On 2024-04-07 19:32, Stan Gammons via groups.io wrote:

To try to
duplicate the spackle finish; I used a #52 drill.

*** How does a drill make a spackle finish?

- Jerry, KF6VB

I had a sort of similar situation. I needed to regulate a high voltage
for a tube rig. The PS that I had delivered 325V and I needed 275. I put a zener
diode across the pass transistor to guarantee that the voltage across it wouldn't fry it during turn-on and turn-off. I also used a long series string of diodes to get the 325
down to 290 or so, so the pass transistor only had to drop 15V.

- Jerry, KF6VB

It was a very warm day in 4 land today, so I finished painting the MS-4
cabinet. It's not "perfect" but it looks a lot better than what it did.
I'm going to leave it as is.? I used Krylon 5557 satin black. To try to
duplicate the spackle finish; I used a #52 drill.

No luck with the T-4X today. I'm going to set it aside for a while and
come back to it later.


73

Stan
KM4HQE

It is the boost voltage for the VCO so it is pretty low current. It runs one op amp that drives the tuning voltage to the varactors. Total capacitance between the 78L24 and the op amp is 3x 1uF, with an inductor in series with one of the caps. OTOH the input filter capacitor is 1uF. Apparently it doesn't take much to filter 46 KHz ripple. I don't think they run warm but I didn't check as I wanted to get the rig back on the air.

I'll give it the finger test the next time I have a TR7 open.

73

-Jim
NU0C

On Sun, 7 Apr 2024 11:37:53 -0600
"Bill Leonard N0CU" <billincolo73@...> wrote:

Jim,
Given the high input voltage, voltage spikes are certainly a possibility,
but I would also investigate how hot the device is running. High device
temps accelerate failure rates.
If I remember correctly, the protection diode across these devices is
recommended when there is a large filter cap on the output. When the input
voltage is removed, the device becomes reversed biased. The higher the
output voltage and the higher the capacitance, the more likely that there
can be a problem.
Bill N0CU

On Sun, Apr 7, 2024 at 10:13?AM Jim Shorney <jimNU0C@...> wrote:

One of my TR7s suffered a 24V regulator failure yesterday. It was just
sitting there running and failed overnight. Anecdotal evidence suggests
that the 78L24 is a high failure rate part and in my limited sample of <10
I have now replaced three over the years in different rigs. But why?
Inquiring minds want to know.

Other 78xx and 78Lxx devices are used in the 7 line gear and they don't
fail as often. Maybe it is the voltage? One data sheet that I found with
specs for the 24V chip lists 40V as the maximum input voltage. Input on the
TR7 PS board was measured at about 36V unloaded. Maybe spikes stressing the
IC causing eventual failure. Reducing the input voltage with a small series
resistor is something that could be investigated. Ten volts of headroom in
this circuit seems like overkill (pun intended). I have not tried this.

One thing in the back of my mind was that a protection diode across the
regulator is suggested in some 78xx data sheets. I had to go back to an
older TI data sheet to find it.



The idea here is that the regulator can be damaged if for some reason the
input voltage drops below the output voltage. A back biased diode from
output to input supposedly prevents this. I don't know that this is what is
happening but diodes are cheap (or sometimes free) so I added one.

If both me and the rig are still around in 20 years I will let you know
how it works out.


--

73

-Jim
NU0C