[Boatanchors] R-388

[Al Parker]

Hi Howie,
	One of those "small red micas" that has been a problem in several 
R-388's for me was pointed out by John Poulton 6-8 yrs ago.  It's C-204, 
between the detector and AVC sections of V-110.
	It does cause squirrely results in AVC action, maybe at least one of 
your problems.
	There's another right there, C-206, that is the same type/value, a 
"CM-100" I think they're called.  Seems like I've replaced that one, too.
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole

On 5/26/2018 8:42 AM, howard holden wrote:
> No these are the caps in the tuned circuits. My voltages look good, no +
> V where it shouldn't or low screen or plate V so I'm not suspicious of
> coupling caps or bypasses. But I read somewhere (don't remember where
> nor can I find) that there were some small red micas that were suspect.
> And some of those are buried. But thanks for the ideas!
> 
> 
> 73, Howie
> 
> 
> On 5/25/2018 9:06 PM, Robert Downs wrote:
>> Howie,
>>
>> After reading your first three paragraphs, my thought was that the problem sounded like missing or leaky decoupling capacitors.  I've not had that problem with my R-388 so I didn't know that they were red.
>>
>> Robert Downs
>>
>>
>> -----Original Message-----
>> From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of howard holden
>> Sent: Friday, May 25, 2018 7:35 PM
>> To: boatanchors
>> Subject: [Boatanchors] R-388
>>
>> Started working on an R-388 two years ago, then life got in the way. Getting back to it, and the old girl�s coming to life.
>>
>> I�ve cleared up some issues with loose/misaligned cams on the IF slug rack and slippage on the drive shaft that moves the IF gears, reset the drum pointer and dial so that X.100 Kc appears where it should. Tracking on the VFO seems pretty tight.
>>
>> Aligning the IF, slugs seem to tune correctly, the caps seem to have relatively little effect. But reception is pretty good on the 2 and 3 Mhz bands. Aligning the RF (4-7, 8-15, and 16-30Mhz) same situation on the 4-7 and 8-15 sections, but the 16-30 section adjusts well on both slugs and caps.  Also reception is good on 4 Mhz, fair on 5 and 6, poor on 7, good on 8Mhz, fair on 10-13, poor on 14 and 15 Mhz. Haven�t REALLY made an evaluation on 16-30 yet.
>>
>> I recall having seen info that the little red mica caps (on most of the RF and IF coil/cap assemblies but not present on the 16-30) can be an issue. Is this good sensitivity on the low end but poor on the high end caused by flaky red caps? Also getting the same effect on tuning the caps on the BC band, although that band seems to be working quite well overall.
>>
>> Comments/hints/suggestions welcome!
>>
>> Howie WB2AWQ/7
>>
>> ______________________________________________________________
>> Boatanchors mailing list
>> Home: https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailman.qth.net%2Fmailman%2Flistinfo%2Fboatanchors&data=02%7C01%7C%7C3adda9bde0dd427ae38c08d5c2be00e3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636629043667377920&sdata=GHChCs6gW%2Be4SkvrbCKX%2FNBzvbVH39SGYuZnroswrYM%3D&reserved=0
>> Help: https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailman.qth.net%2Fmmfaq.htm&data=02%7C01%7C%7C3adda9bde0dd427ae38c08d5c2be00e3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636629043667377920&sdata=TcTFmIzWyH75F6%2FJbhKeE9d%2F0iUp9b1y4hXoeJw%2BzY4%3D&reserved=0
>> Post: mailto:Boatanchors at mailman.qth.net
>>
>> List Administrator: Gary Harmon, K5JWK
>> ** For Assistance: gharmon at idworld.net **
>>
>>
>> This list hosted by: https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.qsl.net&data=02%7C01%7C%7C3adda9bde0dd427ae38c08d5c2be00e3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636629043667377920&sdata=rk4IA94NAiSQJY%2FvUnSV2C8%2FgHyHNO7HxPwZ60G6cFk%3D&reserved=0
>> Please help support this email list: https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.qsl.net%2Fdonate.html&data=02%7C01%7C%7C3adda9bde0dd427ae38c08d5c2be00e3%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636629043667377920&sdata=mSoHOvgppEdaTdR4Tycx9UmaqHOFNq5jqIuElgIWvck%3D&reserved=0
>>
> 
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
> 
> List Administrator: Gary Harmon, K5JWK
> ** For Assistance: gharmon at idworld.net **
> 
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> 

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus