[ARC5] BC-453 Question BC-454 Also

[J Mcvey]

The variac is NOT isolated from the line, so recruiting  directly from a variac is dangerous.You didn't mention how you were going to power the 24V filaments...
I hope you meant that you have an isolated power supply which you intend to bring up slowly.
I would re-cap it, which can be done by cutting the flower pots open and replacing the guts with metal film or mylar 400 V types.  Solder them back together when done. Looks pretty good - especially if you "finish" the joint with a hot air solder tool.
A quick way to assess the health or lack thereof, is to check the center point of the two power resistors.It should be close to 35% of the DC B+ supply . If it's quite a bit lower, you either have the "top" resistor in the chain gone high or leaky caps or both. If it's much greater than 35% then the "bottom" resistor is open.





    On Friday, April 3, 2020, 10:22:59 AM EDT, Bob Groh <bob.groh at gmail.com> wrote:  
 
 First of all, I am NOT a collector - just an old timer ham radio operator who (FYI) made and used a Q5'er 'back in the day' (i.e. 1957 or thereabouts) - loved it by the way. Huge nostalgia thing for me and I sort of intend to build a new one some day.
Having said that, I recently resurrected two LF receivers (a BC-453 and a R-23 (which is basically a BC-453 in Navy trim - all black - the 453 is unpainted aluminum)) with the idea of seeing what I had and to lay plans for further work.  That, of course, meant going down the 'rabbit hole' and chasing down lots of interesting information and opinions. Here are some of my thoughts:1.  If your BC-453 is 'unmodified' and in virgin state - don't muck with it. Today unmodified military gear is rare. The collectors will applaud you.2.  If it is mucked up anyways, then go for it. Roam the web - lots of good information out there on bring them back from the dead.
My other thoughts: My two were a mixed bag. The BC-453 has great metal work but had been hacked a bit to add a power supply on the back and it is minus the BFO coil and the audio output transformer. Have an offer for a BFO coil but the audio output transformer - well, I'll have to hack that in. This is probably the one that I will use for my Q5'er nostalgia machine. 
The R-23 is in great shape but missing a bit of metalwork - the dyno area is a bit hacked but other than those two areas the rest looks great.  So I am going to leave it alone.
Power supply - I am NOT going to try to build one on or in the R-23 but rather an external one. Aiming at transformer isolated, 150 VDC'ish (no higher) and keeping filament at 24 VAC. 
Cap replacement - absolutely. I am not going to try 'stuffing' the pots - just little mini-boards. I will save the pots for others.
As a side note, if you have bits and pieces (e.g. tuning knob) that are sought after, you might consider selling those separately.  I don't care if I have a hacked up tuning knob assembly but a collector really wants the real thing.
Just my thoughts. Have fun.
73Bob Groh, WA2CKY
On Thu, Apr 2, 2020 at 10:27 PM Whitebear1122 <whitebear1122 at comcast.net> wrote:

Today I brought in from the garage a BC-453 that has been sitting out there for several years. It has been sitting in an old timers basement since the early 60’s so it was gunky with grime.  So I had to clean it up before I wanted to get to close to it..  It cleaned up nicely with some GOJO and a tooth brush, and looks great.

I’m thinking of building a Q5’er with it.  

Question for you experts:  How would you approach powering this up? One option is to just plug it into a variac and slowly bring it up and find out what happens.  Another approach would be to disconnect all the 0.05 or 0.5 cans and measure capacitance and leakage current.  Another approach is to shot gun replace those caps.  

I know there has been a lot of discussion about recapping the BC-348 Micamold caps and just getting it over with.   What about the ARC5 receivers?  What has been your experience?

Thanks, Scott WA9WFA




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