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Drake W4 wattmeter part three

 

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Gang,

Before I celebrate too much, I have a couple more W4 meters that have the opposite problem—too much deflection—can’t set the calibration

If I apply 100W, the meter begs, and if you switch scales to 2000W, 100W of RF shows 900W

Again, a look at the simple schematic will help when I try to explain what I ended up doing.

On the 200W scale, trimmer R4 sets the calibration. On the 2000W scale, trimmer R4 is still used, but then R3, R2 are in series.

So I measured resistance between the cathode of D1 to the brown wire that goes to the 200W selector. I read 12K (the trimmer is actually 12K) and of course I can adjust the value down to about 100Ω or so.

Switch to 2000W scale, and measured about 80KΩ of resistance from the cathode of D1 to the wire that goes to the 2000W selector tab.

The wiring to both the 200W and 2000W meter positions are in perfect working order. So why does the meter go off scale no matter where the trimmers are set?

What I ended up doing was to insert a resistor in series with the wire that runs to the selector switch on both power levels.

On the 200W scale, I ended up with 62K, and the 2000W scale required a whopping 220K!

I’m wondering if at one time someone swapped out the meter for something much more sensitive instead of the stated 200uA one Drake used.

Mike wb8vge
 

On 2024-01-21 09:21, mike bryce wrote:

I’m wondering if at one time someone swapped out the meter for
something much more sensitive instead of the stated 200uA one Drake
used.
*** I can easily imagine somebody scoring a nice meter and just sticking
it in.

Once upon a time...

...As a preteen in San Francisco, I attended an after school electronics
program known as "Lux Labs". We had lectures, and we built projects. One
of our first projects was a crystal radio. The program provided us with all
the parts, including a cheap headset.

Down on Radio Row, I scored a really nice Western Electric headset.

For some reason, my crystal radio never worked. The instructor checked all my
wiring, pulled on my solder joints - all OK. But not a peep out of it.

Some twenty years later, I woke up one morning, sat up in bed, and said "600 ohms!"

...which was surely the input impedance of that nice WE headset. Way too low for
a crystal radio.

- Jerry, KF6VB
 

Yeah, there were some surplus Motorola repeater rack meters floating around eBay for a while that were almost the correct Jewell version but were more sensitive. I bought one, added an external shunt, and rescued a WV4. It's possible that someone got ahold of one of those and didn't understand the concept.

73

-Jim
NU0C

On Sun, 21 Jan 2024 09:28:41 -0800
"jerry-KF6VB" <jerry@...> wrote:

On 2024-01-21 09:21, mike bryce wrote:

I’m wondering if at one time someone swapped out the meter for
something much more sensitive instead of the stated 200uA one Drake
used.
*** I can easily imagine somebody scoring a nice meter and just sticking
it in.

Once upon a time...

...As a preteen in San Francisco, I attended an after school electronics
program known as "Lux Labs". We had lectures, and we built projects.
One
of our first projects was a crystal radio. The program provided us with
all
the parts, including a cheap headset.

Down on Radio Row, I scored a really nice Western Electric headset.

For some reason, my crystal radio never worked. The instructor
checked all my
wiring, pulled on my solder joints - all OK. But not a peep out of it.

Some twenty years later, I woke up one morning, sat up in bed, and
said "600 ohms!"

...which was surely the input impedance of that nice WE headset. Way
too low for
a crystal radio.

- Jerry, KF6VB






--

73

-Jim
NU0C
 

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here is one I’m working on, and I’m fairly confident it’s not a Drake factory meter.

Mike, wb8vge?

On Jan 21, 2024, at 2:11 PM, Jim Shorney <jimNU0C@...> wrote:


Yeah, there were some surplus Motorola repeater rack meters floating around eBay for a while that were almost the correct Jewell version but were more sensitive. I bought one, added an external shunt, and rescued a WV4. It's possible that someone got ahold of one of those and didn't understand the concept.

73

-Jim
NU0C
 

Mike, I'm curious.? How did you get so many bad ones?? Hamfest find?

73,

Steve Wedge, W1ES/4

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

Sent with secure email.

On Monday, January 22nd, 2024 at 4:53 PM, mike bryce <prosolar@...> wrote:

here is one I’m working on, and I’m fairly confident it’s not a Drake factory meter.

Mike, wb8vge?

On Jan 21, 2024, at 2:11 PM, Jim Shorney <jimNU0C@...> wrote:


Yeah, there were some surplus Motorola repeater rack meters floating around eBay for a while that were almost the correct Jewell version but were more sensitive. I bought one, added an external shunt, and rescued a WV4. It's possible that someone got ahold of one of those and didn't understand the concept.

73

-Jim
NU0C
 

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Yeah, over the years, I’ve collected quite a few. I’ve never really did anything with them other than line them up on a shelf and look at them. With the weather so crappy, I decided to take them down and test them.?

I have a couple of WH7 watt meters and one was really out of calibration. It calibrated without issue.?

Heathkit loved to build ‘oscopes….. Drake loved to build wattmeters!


mike wb8vge

On Jan 22, 2024, at 5:18 PM, Steve Wedge, W1ES/4 via <w1es@...> wrote:

Mike, I'm curious.? How did you get so many bad ones?? Hamfest find?

73,

Steve Wedge, W1ES/4
 

Yeah, we all have "those projects".? I'm finally tearing into a TS-830S that I thought had RF switching issues.? It turned out that the meter switch wasn't making contact.? I took it apart and cleaned it and it's now working but has some other messed up things going on.

Steve Wedge, W1ES/4

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

Sent with secure email.

On Monday, January 22nd, 2024 at 5:22 PM, mike bryce <prosolar@...> wrote:

Yeah, over the years, I’ve collected quite a few. I’ve never really did anything with them other than line them up on a shelf and look at them. With the weather so crappy, I decided to take them down and test them.?

I have a couple of WH7 watt meters and one was really out of calibration. It calibrated without issue.?

Heathkit loved to build ‘oscopes….. Drake loved to build wattmeters!


mike wb8vge

On Jan 22, 2024, at 5:18 PM, Steve Wedge, W1ES/4 via <w1es@...> wrote:

Mike, I'm curious.? How did you get so many bad ones?? Hamfest find?

73,

Steve Wedge, W1ES/4
 

On 2024-01-22 14:36, Steve Wedge, W1ES/4 via groups.io wrote:
Yeah, we all have "those projects". I'm finally tearing into a
TS-830S
*** I *loved* my TS-830S. Best radio I'd ever had. My only problem with it
was the crappy circuit boards. They were not very tolerant of rework.

- Jerry, KF6VB
 

I'm fortunate in that this set seems to be unmolested AND has BOTH 500 Hz CW filters. Not bad for $80 at NEARfest a couple of years ago!



Steve Wedge, W1ES/4

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

Sent with Proton Mail secure email.

On Monday, January 22nd, 2024 at 7:20 PM, jerry-KF6VB <jerry@...> wrote:


On 2024-01-22 14:36, Steve Wedge, W1ES/4 via groups.io wrote:

Yeah, we all have "those projects". I'm finally tearing into a
TS-830S

*** I loved my TS-830S. Best radio I'd ever had. My only problem
with it
was the crappy circuit boards. They were not very tolerant of rework.

- Jerry, KF6VB
 

Mike

I placed 2 each 1N295's in the mail to you this AM. I think these are the spare 2 I bought for my W4 when I was having problems.? Enjoy

73? Bob

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