Re: {Collins} Wattmeter PEP

Mike, et al,

I guess I am going to have to chime in here. Our PDC-1 Peak Reading Adapter kit was originally designed and implemented in Collins 312B-4/5 watt meters. Thousands of these circuits are in use worldwide not only in Collins watt meters, but in many others as well.

Our kit does not affect the calibration or accuracy of the watt meter, however, it does accurately show voice peaks for SSB signals with an adjustable slow decay rate. This is an active circuit that uses a dual op-amp. In the Collins meters which utilize meter lamps, this circuit uses the 6.3 volt ac line for power. With a flip of the switch, you can immediately go right back to average reading mode.

This circuit works so well, that many are even used in laboratory grade meters, such as the Bird, Telewave and Coaxial Dynamics units.

In my personal 312B-4, I used a switch that was mounted on a bracket I pinched between the cabinet and the directional coupler, so as not to have to drill any holes...

No offense, but this active circuit works better than any capacitor style circuit for the purpose of reading true PEP levels.

Please contact me, if you have more questions on how to convert your average reading watt meter to true peak reading...
Floyd Soo, W8RO
President, Hi-Res Communications, Inc.
Founding Member; Past President, Board Member and Net Manager, Collins Collectors Association

Sent from my 4G LTE smart-aleck phone

<div>-------- Original message --------</div><div>From: Mike Waters <mikewate@xxxxxxxxx> </div><div>Date:05/01/2015  6:40 PM  (GMT-05:00) </div><div>To: collins@xxxxxxxxxxxxx </div><div>Subject: Re: {Collins} Wattmeter PEP </div><div>
</div>Sounds like a plan. Please let us know what the new diodes do before you
add anything else.

You want suggestions ... my suggestion is to make your proposed switch
select between (1) the standard circuit (probably with the diode mod), (2)
my 7 uF tantalum cap mod, and (3) the PEP board.

In fact, before you do anything with capacitors or PEP board, why don't you
make it so you can switch between the original diodes and the new ones?!

Tantalum capacitors can have a slight advantage over electrolytics in some
time constant circuits. (I forget the details, but maybe it's something
about the rise/decay times being more linear). Whether it would make a
significant difference in this case, I can't say for sure. If I had the
tantalums, I would send you some at no charge, but I don't.

Reading average power is important. My question is whether or not that PEP
board will also show the average similar to the way that my capacitor mod
does. Based on SSB waveforms that I've seen on a scope, and reading the
info at ,  I have some
nagging doubts about that.

Gentlemen, I am not trying to show off or pick a fight with anyone. I
simply am trying to learn something and share my own experiences.

73, Mike

On Fri, May 1, 2015 at 3:28 PM, <donroden@xxxxxxxxxx> wrote:

> Quoting Colin Lamb <k7fm@xxxxxxxxxxxx>:
>  I agree with Bill about the PEP wattmeter board.  I have added similar
>> boards to a number of wattmeters.
> As do I.
> I just wanted to install modern diodes before I added the pep board.
> I want to add a small  ( hidden or nearly so ) switch attached to a
> bracket on one of the front feet of the 312B-5 and the 312B-4  to switch
> between average  ( but correct ) and pep.   Suggestions appreciated !!
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