[R-390] Y2K Errata

[pete wokoun]

Craig,
 
On your three findings, they appear correct on the Y2K schematics!
 
Amazing, 12 years out and folks are still proofreading it,  LOL!
 
Mele Kalikimaka and Hauoli Makahiki Hou to all.

Pete KH6GRT
 
 
 

> From: hamfish at efn.org
> To: r-390 at mailman.qth.net
> Date: Wed, 26 Dec 2012 13:43:24 -0800
> Subject: [R-390] Y2K Errata
> 
> Hello All,
> 
> The last few days I've been going over and comparing two R-390/A's. One
> being a Motorola and the other a Amelco. The trouble has been located, I
> think. But in the process a few items might be amiss in the Y2K manuals.
> 
> So:
> #1: In section 5 on page 20, where the AF sub-chassis, voltage and
> resistance diagram is shown; the LOCAL AF OUTPUT V603 pin #1 voltage should
> be 0 (zero) volts, not 10 volts. Ten volts is a lot of grid voltage. IMHO
> 
> #2: Same page, V604 a 6AK6, the description should be LINE AF OUTPUT, not
> LOCAL.
> 
> #3: In section 7 on page 43; this is the IF Amplifier Sub-Chassis section;
> the value for C537 should be 180 pf, not 1800 pf.
> 
> The trouble with the Motorola seems to be silver migration on C532, C537, &
> C546. I've pulled all three from a spare hanger queen victim and checked the
> values. C537 is without a doubt 180 puffs. The Sprague TO-6A does well with
> the value & insulation resistance, but it can't handle the silver migration
> stuff. All else checks good; tubes, wiring, resistors, etc. The voltage
> readings on V507, pins 1,2,3 & 6,7,8 are bizarre to say the least. Same with
> V509 on pins 1 &2. The common item, silver mica capacitors. 
> 
> Happy Holidays,
> 
> wd8kdg
> Craig
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:R-390 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html