[Milsurplus] RAK/RAL Muting

[William Props]

Hi Ken,

I was trying this on 160M with just 100W. I was hoping to monitor my
sending on the receiver, but the oscillator seems to lock onto the transmit
freq like typically happens with an overloaded regen. It instantly
recovers. I've tried setting the regeneration both right at the edge of
oscillation and way beyond that. No change. I've replaced a leaky mica, and
a handfull of resistors. All of the oil filled caps are original. I'm using
the original power supply and cable. There are a few holes in the back of
the cabinet I could try sealing up.

Thanks,
Chris

On Wed, Mar 30, 2016 at 8:15 PM, Kenneth G. Gordon <kgordon2006 at frontier.com
> wrote:

> On 30 Mar 2016 at 18:22, William Props wrote:
>
> >
> > Was there any type of muting used with the RAK/RAL on ship installations
> when used with a
> > transmitter or was the receiver expected to handle strong local signals?
> I've tried using my RAL
> > with a separate receiving antenna for full QSK, and the transmitter just
> blocks the oscillator like
> > expected. How was it done on the ships?
> >
> > Chris
>
> Hmmm....well, I used an RAL-7 for at least 12 years as my main station
> receiver and
> operated full-QSK CW with transmitters up to a KW input. I was first
> licensed in 1956, and
> go the RAL-7 about a year later.
>
> I used separate tx and rx antennas.
>
> From my experiences with it, I consider the RAL to be the finest HF TRF
> receiver I have
> ever used. Mine was very sensitive, stable as a rock, plenty selective
> enough for me, and
> extremely reliable.
>
> I was very much involved in CW message-traffic handling at the time
> (1960s), and at this
> late date, I don't remember ever havning any sort of problem with blocking
> such as you
> seem to describe.
>
> On the other hand, my RAL-7 was NIB when I got it, so maybe that has
> something to do with
> your issues: I don't know.
>
> I DO know that many Navy Sparks preferred the RAK/RAL to the later RBB/RBC
> receivers
> because the RAK/RAL was less subject to interference from nearby
> transmitters than the
> later receivers. The RAK/RAL were unusually well filtered for RF ingress
> by means
> other-than the antenna.
>
> You say that the transmitter blocks the oscillator: how long does it take
> to recover? Is the
> oscillator (detector) pulled off frequency? What, exactly, happens when
> you hit the key on
> your transmitter? Have you gone through your RAL and tested or replaced
> the caps? Many
> of those are bad by this late date. Are you setting the regeneration
> control on the very edge
> of oscillation, or deeper into that? I always set my regen control on the
> very ragged edge of
> oscillation. What sort of power supply are you using? At the time, my
> power supply and
> cables were all stock and original.
>
> I will repeat that the RAK/RAL had every single lead that went into and
> out of the receiver
> very well filtered with RF chokes and bypass caps, so that the only way RF
> could get into
> the receiver was by the antenna connector, and even THAT was filtered in a
> way that
> allowed RF to the 1st RF amp grid but to no where else.
>
> The power-supply cable is double-shielded and bypassed at both ends, as is
> the AC line
> into the power supply. The audio output connections are also filtered, and
> the front-panel
> phone jack is in its own shielded box with RF chokes and bypass caps in
> it.     The cabinet
> has a springy thing around the periphery of the box which ensures an
> RF-tight contact
> between the receiver chassis and the box, and the box has a large can in
> the rear
> containing another filter through which the power supply cables and audio
> to an external
> speaker or audio control were fed.
>
> Ken W7EKB
>
>
>
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