[ARC5] Using BC-454 as backend

[Bob kb8tq]

Hi

> On Jan 24, 2018, at 10:16 PM, D C _Mac_ Macdonald <k2gkk at hotmail.com> wrote:
> 
> I used an R-25/ARC-5 for the fixed I.F. for a Morrow 5BR-1 converter as my primary station receiver for several years in the mid-1050s.

Just prior to the Norman Conquest of England in 1066 ….really tough to keep up with hobbies after that …. :)


>   I believe you would be happier from a selectivity standpoint going that way instead of trying to convert your BC-454 I.F. to 1525 kHz.


I agree 100% that the R-25 would be a better option 

Bob

> 
> 73 de Mac, K2GKK/5
> (Since 30 Nov '53)
> Oklahoma City, OK
> USAF Retired 61-81
> FAA Retired 94-10
> 
> 
> From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> on behalf of Ian Wilson <ianmwilson73 at gmail.com>
> Sent: Wednesday, January 24, 2018 20:45
> To: ARC5
> Subject: [ARC5] Using BC-454 as backend
>  
> I am working on using a BC-454 as backend to a Morrow converter. The
> Morrow produces 1525kc for a BC band car radio as backend. My plan
> is to use the BC-454 with IF and BFO tuned up from its original 1415kc.
> The idea is to make 100% reversible changes only.
> 
> So far I have dug out and reanimated a BC-454. This works OK as a receiver -
> tested with 4MHz input. Tested all the tubes - all good except a dead 12SK7.
> 
> So the next step was to remove the RF amplifier and converter tubes and
> tap into the input to the first IF transformer. This appeared to be working OK.
> 
> Next step is to retune the BFO, align the IFTs to 1525kc (obviously I don't
> know whether they will pull this far. If not, have to think of a Plan B). However,
> came across a problem - if I retune the BFO too far it apears that the IF
> strip itself starts to oscillate. Not sure whether I am diagnosing this correctly.
> 
> Perhaps a screen bypass capacitor in the IF stages? There is some sign of
> leakage from some of the metal can capacitors.
> 
> Originally I left the primary of the 1st IFT floating. Bad idea. However, putting
> a few kOhm (with series 0.01u cap to keep the HT happy) to ground made no
> difference whatsoever.
> 
> I'm sure numerous people over the aeons have trodden this path. Interested
> in any suggestions.
> 
> 73, ian K3IMW
> 
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20180124/84477e27/attachment.html>