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PEP Conversion for DRAKE W-4 Wattmeter

unit_399

unit_399

EL CAPO
Jun 17, 2008
2,313
3,740
273
ALEJANDRIA, COLOMBIA SA
One of the 1st pieces of equipment I bought when I got into CBing in the late 60s was my trusty Drake W-4 wattmeter. Over 60 years old and still works and looks like new. Only downside . . . AVG reading only, no PEP.
I ran across a site online from K4DPK offering a PEP conversion kit for the W-4. The price was right, so I thought I'd give it a shot and bought it. Received it yesterday. Nicely built and GREAT instructions.

PEPBOARD2.png



The kit is designed to bolt on to two existing screw holes on the W-4s sensor box.

PEPBOARD3.png

I removed the box (4 screws) and installed the PEP kit. Cut a wire on the W-4 and spliced in the wires from the PEP kit.

PEPBOARD4.png

The kit requires an 8 - 14 vdc supply. I chose to use a rechargeable 9 volt battery.
I have enough wires running around my station.

Reassembled the meter, hooked it up, and it was ready to go. Easy calibration. and "hang time" adjustment.

PEPBOARD5.png

PEP/AVG W-4 works perfectly. Easy 45 minutes work.

- 399
 
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unit_399 said:
One of the 1st pieces of equipment I bought when I got into CBing in the late 60s was my trusty Drake W-4 wattmeter. Over 60 years old and still works and looks like new. Only downside . . . AVG reading only, no PEP.
I ran across a site online from K4DPK offering a PEP conversion kit for the W-4. The price was right, so I thought I'd give it a shot and bought it. Received it yesterday. Nicely built and GREAT instructions.

View attachment 65612



The kit is designed to bolt on to two existing screw holes on the W-4s sensor box.

View attachment 65616

I removed the box (4 screws) and installed the PEP kit. Cut a wire on the W-4 and spliced in the wires from the PEP kit.

View attachment 65613

The kit requires an 8 - 14 vdc supply. I chose to use a rechargeable 9 volt battery.
I have enough wires running around my station.

Reassembled the meter, hooked it up, and it was ready to go. Easy calibration. and "hang time" adjustment.

View attachment 65614

PEP/AVG W-4 works perfectly. Easy 45 minutes work.

- 399
Click to expand...
I have been using his PEP Kit in my WELZ SP-600 for 6 meters for many years & it also works very well. He makes some great products for a great price & he's a good guy from all I have heard.
 
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UPDATE: Put the converted W-4 inline today for the first time. Meter was DOA in the PEP mode. My fault. The PEP board has a "hang time" (peak hold) adjustment and I turned it down so far that I ran the slider off of the carbon track in the variable resistor. I keyed up in AM mode, and backed up the adjusting screw until the meter just began to read in the PEP mode. I like my meters to bounce around in SSb, so am not a fan of peak hold. The meter still holds a little, but recovers pretty quick. Great product. Highly recommended. Made my old W-4 super useful.

- 399
 
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I'm ready for a non-linear hang-time response.

The gold standard for true PEP readings for years was to key the mike, turn up the mike gain and whack the front of the mike with a pencil.

If the reading was a match for what it shows for "Heeeellooo" you're good to go.

Just one problem. The hang time makes it impossible to use it for adjusting anything. Can't see a peak if there's no downhill side to the meter's response. I cheat and use a 'scope, but my peak adapters are all set for a too-short hang time. This reduces the PEP reading by at most 10 percent, but so what? Any time a customer sees more on his meter at home that he did on my Bird here, they never complain. I'm just impatient about seeing the needle fall back. If the peak power reading is a few percent low, so what?

Seems to me a simple microcontroller program could look at the length of time the meter is being "hung" and look at the quarter of a second or so that follows it. If it's zero, then just short across the peak circuit's hold capacitor and produce a reading that's better connected to that moment's reality.

Would love to see someone develop the "intelligent" hang time feature. Probably won't be me.

73
 
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nomadradio said:
I'm ready for a non-linear hang-time response.
The hang time makes it impossible to use it for adjusting anything. Can't see a peak if there's no downhill side to the meter's response.
Would love to see someone develop the "intelligent" hang time feature. Probably won't be me.
Click to expand...
My sentiment exactly. I like to see what my output looks like in real time. Being able to watch the instantaneous output's peaks and valleys, I'm able to evaluate (kinda) the differences in microphones, audio processing, etc. When the meter needle just "floats" you lose the ability to do any of this.

- 399
 
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unit_399 said:
My sentiment exactly. I like to see what my output looks like in real time. Being able to watch the instantaneous output's peaks and valleys, I'm able to evaluate (kinda) the differences in microphones, audio processing, etc. When the meter needle just "floats" you lose the ability to do any of this.

- 399
Click to expand...
What sort of battery llfe are you having on the W-4 & Peak kit?
I've heard people w/ Bird meters complain about batteries dying when left On overnight. Is that a problem with Phil's board?
I installed Phil's board in a W-4 last May '23 but wired to a PSU and yes, the extra wire can be a fuss.

neil, NYC
 
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The original Bird peak adapter used two 9-Volt batteries, and a first-generation op-amp chip. First generation, as in power hog.

We use adapters based on a newer, low-power chip LM358. A whole world of improved analog chips have emerged since the original Bird peak adapter, and the 358 might not be the ideal choice any more.

This has one advantage. It only takes one 9-Volt battery to run it. I use rechargeable 9-Volt. They get swapped into the charger once a week. Leaving a meter in peak mode overnight doesn't discharge it completely. But doing that two days in a row will pull it down.

Biggest reason I use a battery is the signal-rectification issues we had using an external DC wall wart. An amplifier with one cover removed would bleed the peak adapter and cause unrealistically-high readings. Selecting an antenna in place of the dummy load would also 'bleed' the peak adapter.

The adapters in our Bird 43s came from "LNA Technology". No idea if they are still around, but this design has been duplicated by a list of outfits the last ten years.

I'm skeptical of the "times 2, times 5" feature. More than once I have damaged a Bird element with more RF power than it was rated. Putting 500 Watts into a 100-Watt element just makes me skeptical.

In particular, Coaxial Dynamics elements may not be as stout as the Bird originals. I have one of their 10 kW slugs that's labeled "10 kW peak". When a particulary big amplifier pegged it on peak mode, I switched to average. When the average reading reached about 4500 Watts, the element went dead.

Oops.

If you plan to use an adapter with the "multiplier" feature I would recommend sticking with original Bird elements before pushing a "multiply" button.

73
 
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Naysayer said:
What sort of battery llfe are you having on the W-4 & Peak kit?
I've heard people w/ Bird meters complain about batteries dying when left On overnight. Is that a problem with Phil's board?
I installed Phil's board in a W-4 last May '23 but wired to a PSU and yes, the extra wire can be a fuss.

neil, NYC
Click to expand...
I've been using the same 9V battery since the end of September last year. Still hanging in there. I keep it in line 100% of the time because I was too lazy to install a switch. Very happy with the PEP kit. Highly recommended.

- J.J. 399
 
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Where can you actually buy these from, have a Drake W-4 and a WH-7 would like to put one in each, see a lot of reviews on them but cant find a site to buy them from?
 

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