[Milsurplus] BC-348-Q restoration

[Mark K3MSB]

Well,  my web site had the detailed pictures of the 4 modules but nothing
about their removal.   So,  after working 8 hours and spending 3 hours on
yard work,  I did some fast scrambling and updated my web site with some
removal notes.   First pass,  but if I didn't get this up tonight it would
probably fall off the radar....   I will try to align my terms with those
in the manual at a later time.    Comments welcome.

http://www.k3msb.com/bc348/main.html

Scroll down and select the link for "Antenna / RF / Detector / Oscillator
(sub)Assembly Photos"

73 Mark K3MSB




On Mon, Jun 15, 2020 at 8:22 PM Dennis Monticelli <
dennis.monticelli at gmail.com> wrote:

> OK.  Found another mod.  This one was hidden behind the front access
> plate.  The first RF stage 6SK7 had been rewired as a pentode. I'm thinking
> there must have been a published mod way back when on getting more gain the
> easy way.  Stock is triode connected.  I presume the designers chose a
> triode for lower noise.  Meanwhile the impedance matching to the next stage
> and the overall gain distribution is all tied to that triode connected
> stage.  Unless someone tells me otherwise, I will reverse the mod.
>
> Dennis AE6C
>
> On Mon, Jun 15, 2020 at 8:00 AM Dennis Monticelli <
> dennis.monticelli at gmail.com> wrote:
>
>> Hi guys,
>>
>> I am beginning my first BC-348 restoration. Luckily the Q model is the
>> simpler of the two basic types. It appears to have decent caps, not
>> micamol. Not badly hacked either.
>>
>> First order of business has been to remove unwanted mods. That means all
>> other than the AC supply, which fortunately was well executed.  A 1uF
>> bypass cap on the cathode of the 2nd IF has been added.  The stock 0.1uF
>> bypass is still there.  Was this a published mod to change AVC action?
>>
>> Regarding the tuning gearing.  It was stiff and I found dried grease.
>> Was any grease used on stock units?  I note the use of brass on steel gear
>> design choices which I recall is naturally lubricating.  What do you
>> recommend regarding cleaning and possible lube of the gears?  I am using
>> WD-40 on Q-tips to clean off the old lube.
>>
>> Any other restoration hints would be appreciated.
>>
>> Dennis AE6C
>>
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