[ARC5] Strange box - Pictures

[Neil Barnett]

The galvanised sheet metal around the VHF unit
suggested to me that it was a TV tuner, but now
that I look closely I see the Navy anchor stamp
and some soldering direct to the aluminium chassis,
a giveaway to its military origins.  So it seems that
the galvanised plate is merely a mounting bracket.
Your info about the frost/freeze plugs is interesting,
thanks.

73 de Neil ZL1ANM


----- Original Message ----- 
From: <WA5CAB at cs.com>
To: <neilba at clear.net.nz>; <ARC5 at mailman.qth.net>
Sent: Monday, October 24, 2005 5:46 PM
Subject: Re: [ARC5] Strange box - Pictures


> Actually, no.  As Gordon mentioned earlier, the well made parts inside the
> black box are the guts out of one of the VHF Command Set receivers, 
> probably the
> R-28/ARC-5.  I finally got around to going into the attic and getting AN
> 08-10-195 Volume 2 (VHF Components).  Everything in the upper photo except 
> the
> trashy power supply related components, speaker, coax, 6V6GT and box 
> matches
> Figure 19 and Figure 20 - VHF Receiver - Right Side.  Everything in the 
> second
> photo except for the previously mentioned exceptions matches Figure 21 and 
> 22 -
> VHF Receiver Left Side.
>
> Someone gutted an R-28 (or maybe a BC-942).
>
> The domed plugs in the top of the 6.9 MC IF transformers are just sheet 
> metal
> hole plugs (with fingers in the holes).  Same function as the black 
> plastic
> ones commonly seen today.  They were fitted to protect the tuning 
> adjustments
> from casual tampering and dust or other contamination.  As were the 
> aluminum or
> plastic caps on top of the IF transformers in the HF and MF receivers.
>
> Incidentally, frost plugs, or freeze plugs as they are called up here, 
> aren't
> really there to protect a cylinder block from freezing.  This is an almost
> universally accepted urban myth dating back to well before anyone on this 
> list
> was born.  The holes being plugged were mostly vent holes during the 
> casting
> process, required to successfully cast a cylinder block with integral 
> water
> jacket.  The fact that they often pop out if the coolant in the block is 
> allowed
> to freeze probably led to the myth.  But the block invariably cracks 
> anyway.
> In other cases, the plugs cover holes required during internal machining 
> of for
> example oil galleries, after which the holes need to be plugged to prevent
> lube oil from leaking out.  In better quality engines such as the 2-1/4 
> litre
> Land Rover, threaded aluminum plugs were used in most vent holes and 
> threaded
> steel ones over the oil galleries.

> Robert Downs - Houston
> <http://www.wa5cab.com> (Web Store)
> MVPA 9480
> <wa5cab at cs.com> (Primary email)
> <wa5cab at houston.rr.com> (Backup email)



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