[Milsurplus] BC-348-Q restoration

[Dennis Monticelli]

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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20200615/c0ddeb23/attachment-0001.html>