Re: {Collins} Need RCA SK3089 diode data (312B-4 mod)

I will make a general comment to everyone..  Making the wattmeter (302C-3)
"More Peak Reading" is not a good plan...  It is then neither fish nor fowl.

To make it Peak Reading (nice to have), just use the very reasonable and
very high quality peak reading wattmeter board mod that is offered by Floyd
Soo, W8RO, and his company is Hi Res Communication. The contact info is in
our Support Directory.

Otherwise, it should be left configured as is so it is an average power
meter the way it was designed.  It is a very good design and can easily be
updated with modern Schottky diodes or modern germanium. Either will work.


Bill Carns, N7OTQ (Trustee K0CXX)
Past President, Collins Collectors Association
Founding Board, Collins Radio Heritage Group
Editor, Signal Magazine
Wimberley, TX
512 618 2762  (Cell)
512 847 7010  (Home)

-----Original Message-----
From: Collins [] On
Behalf Of Mike Waters
Sent: Friday, May 01, 2015 1:42 PM
To: collins@xxxxxxxxxxxxx
Subject: {Collins} Need RCA SK3089 diode data (312B-4 mod)

In 1980, I replaced the original 1N82A diodes in my Collins 312B-4's
directional coupler with these, and I forget exactly why I did (or where I
got the mod info from). The original RCA SK3089 datasheet might give some

Google failed me on this one; all I could find was a cross-reference to an
NTE-112. And based on my past experiences with NTE semiconductor
cross-references, I don't trust the NTE data.

73, Mike

On Fri, May 1, 2015 at 1:16 PM, Mike Waters <mikewate@xxxxxxxxx> wrote:

> My RE 312B-4 has the following mods, which I highly recommend:
> 1.) 1N82A diodes replaced with RCA SK3089 diodes. I forget the details 
> on those.
> 2.) 7.1 uF tantalum capacitors to make it more peak-reading, as the 
> Collins 302C wattmeter has.
>  One 7.1 uF capacitor goes between R3/R5/L1 and ground; the other one 
> between R4/R6/L2 and ground.
>  The negative lead on each tantalum capacitor is grounded.
>  Three 2.7 uF/20v in parallel = 7.1 uF.
> 73, Mike
> On Thu, Apr 30, 2015 at 12:47 PM, <donroden@xxxxxxxxxx> wrote:
>> ... I replaced both 1N82A s  with low conduction / high back 
>> resistance 1N5711s.
>> ... What is the next logical step ?
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