[ARC5] RBB Receiver Question

[Mark K3MSB]

HI Dave

My SOP for bringing up radios is to first verify resistance checks.
 Afterwards, with all tubes removed,  I apply power via variac - slow
bringup,  low value fuse(s) and make sure the transformers work as expected
and current draw is minimal.   I then insert the rectifiers and VR tubes
and again slowly bring up power,  monitoring current draw (again, it should
be minimal) and check tube base voltages.  I check for hot spots, smoke,
etc during both phase.   Next is a slow bring up with all tubes installed
and rates fuses.

I do like your suggestion of monitoring the DC bus currents during
bring-up.

I use a 3 range AC meter when applying power, and that’s what I use for 117
VAC current monitoring.   That doesn’t provide as fine a level of feedback
as individual bus DC meters would.

I think your “leave the filament off” is the same as me just removing all
the tubes except the rectifiers and VR tubes

73 Mark K3MSB



On Fri, Mar 8, 2019, 1:21 AM David Stinson <arc5 at ix.netcom.com> wrote:

> Leave the filament off.  Power the B+ busses and monitor the current.
>
> I don’t remember what the “static, no filament” current should be
>
> on the RBB/RBC, but a look at the diagram should allow you to
>
> figure it.  For example- A refurbed TCS receiver with “good” caps
>
> should draw a steady 15 mA or there abouts.  Leave it like that for
>
> several hours.  If nothing obvious, turn off the B+ and put your finger
>
> on each cap.  If one is warm or hot, it’s leaking.
>
> This won’t find open caps, but it will find the leakers.  Howling
>
> IFs, low audio gain, etc. will point to open caps, but this has helped
>
> me find leakers in a short time.
>
> GL OM DE Dave AB5S
>
>
>
>
>
> *From:* arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net]
> *On Behalf Of *Mark K3MSB
> *Sent:* Thursday, March 07, 2019 7:48 PM
> *To:* List Milsurplus; ARC5
> *Subject:* Re: [ARC5] RBB Receiver Question
>
>
>
> ,
>
> Thanks for the comments guys.     The context was I'm not going to worry
> about replacing them prior to power up.    Performance and tube voltage
> checks may indicate that replacement of some is necessary.
>
>
>
> I have an RBB-6 and RBC-5 along with an RBC-2.    Two need cases.   A
> Case.... a case...  my kingdom for a case.....
>
>
>
> 73 Mark K3MSB
>
>
>
>
>
>
>
> On Thu, Mar 7, 2019 at 7:43 PM Mark K3MSB <mark.k3msb at gmail.com> wrote:
>
> I am almost ready to apply power to my RBB receiver.
>
>
>
> From "NAVSHIPS 91469 Radio Receivers RBB-5, 6 and RBC-5, 6 (1952)",  quite
> a few of the capacitors are listed as paper dielectric,  castor oil
> filled.    These are C341 through C-352 on pages 8-11 and 8-12.
>
>
>
> I'm almost positive these are NOT of the wax paper variety,  but rather
> the typical oil-filled caps -- so I do not have to worry about replacing
> them.
>
>
>
> Just want to be sure....
>
>
>
> Thanks
>
>
>
> Mark K3MSB
>
>
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