[ARC5] SCR-522: Rethinking The Old Gal

[Mike Feher]

Hi Dave –

 

Hey, what power meter is that? I have a lot of the HP ones with sensors But yours looks portable and easier to move around. 73 – Mike 

 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

848-245-9115

 

From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of David Stinson
Sent: Saturday, April 25, 2020 9:14 AM
To: ARC-5 <arc5 at mailman.qth.net>
Subject: [ARC5] SCR-522: Rethinking The Old Gal

 

Once, I was disdainful of the SCR-522 VHF rig.  Not because of its history, which is quite significant, but for aesthetics, calling it an "ugly black lump of a radio."  And it is.

But I'm recently reminded of high school dance days- how there was always the "plain girl" who sat with a friend and never got asked to dance, so a fella would eventually feel bad that she's being left-out and ask her to dance.  To his surprise, once she got past her justifiable reticence, he finds she can "cut a rug" with the best of them, and surprise- she's really quite a nice and fun person.  Some life-long marriages have started this way.

Well, I recently took out the SCR-522 for "a dance," trying to complete some earlier work now that I have some better test gear available and half-an-hour of time every few days.  Once properly restored and carefully aligned, the "plain girl"  surprised me.  The manual specs the receiver sensitivity at around 3 microVolts,  6 as "acceptable."  Given the 9000-series tube front-end and the state of the VHF art in 1943, that's about right.  Well, this lady is doing about 1.5 microVolts for a good usable signal.  The local UNICOM on 122.8 sounds excellent. Transmitter is good as well.
Rigs works peachy on the BC-1303 tester, but the Antenna relay won't throw when connected to the BC-602.  Still working on that issue.

https://youtu.be/NRHB9DlARXM

On crystal substitution using that DDS gizmo-  This rig requires more drive than the SCR-274 VHF.  Square waves at about 10V peak needed for the receiver.  Higher than that and the receiver stops working.  The transmitter requires an even harder whack- 18-20V peak, and the DDS connection at the transmitter crystal socket causes a ground loop with 60 Hz gremlins.  For some reason, the transmitter will self-oscillate with the DDS connected and less than 12-15V drive, probably from the 60 Hz crud.
Luckily, I have crystals close enough to etch to where I need them.

This "plain girl" has won me over.  I don't want to marry her,  but a "dance" now and then is fun.

GL OM ES 73 DE Dave AB5S



 


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