[Hallicrafters] SR-150 Tuning

[Rocco Lardiere]

Ron,

Max power output should coincide with max RF gain for the receiver section,
or it should be darn close.  This is affected by the alignment of both
the -150 and the -400; if the alignments are off, the symptoms would be what
you are describing.  You should not expect perfect tracking - but it should
be very close.  You should be able to adjust for max RF output, and the
receiver sensitivity should be acceptable at that setting (S9 for 50-100 uV
or so).  This sort of problem is common for transceivers from the 60's.
When in doubt, align per the manual - carefully - and then check for
acceptable RX gain/sensitivity coincident with adequate RF output power.

73,

Rocco N6KN

----- Original Message ----- 
From: "Ronald Oberloh" <wa0kds at yahoo.com>
To: "John N. Schwartzberg" <jschwart at ix.netcom.com>
Cc: <hallicrafters at mailman.qth.net>
Sent: Monday, January 05, 2004 3:42 PM
Subject: Re: [Hallicrafters] SR-150 Tuning


> I am in the process of restoring an SR-400 and have noticed the same
> thing.  Is this normal for the Hallicrafter transceivers?  If is is has
> anyone modified the circuit to correct the problem or know what might be
> causing this. If it was a little off it would not bother me but it  is a
> long way off.  If this is not normal then what might be the problem?   I
> have not checked the schematices but knowing a little bit about other
> Hallicrafter products I expect the SR-150 and SR-400 might have a lot of
> circuit in common.
>
> Thanks
> Ron   WA0KDS
>
>
>
> John N. Schwartzberg wrote:
>
> >
> >> Hey Gang -
> >>
> >> I dusted off my radio bench, then the SR-150, to warm up the shack.
> >> I noticed the following while tuning it up on both 20 and 40 meters:
> >>
> >> With a resonant antenna load, peaking both the pre-selector tuning
> >> and the final output tuning for maximum indication on either an
> >> external watt-meter or the internal meter results in relatively low
> >> receiver sensitivity.  I can then increase the receiver sensitivity
> >> with the pre-selector tuning, but at the expense of output.  The
> >> manual includes the following tuning instructions:
> >>
> >> "Adjust the RF Level control until a small indication is seen on the
> >> S-meter.  In the transmit mode, the S-meter indicates the relative RF
> >> voltage.  Adjust the FINAL TUNING control for maximum output and then
> >> adjust the PRESELECTOR for maximum output indication.  Adjust the RF
> >> LEVEL control as required to keep the S-meter below S9, while tuning
> >> the PRESELECTOR."
> >>
> >> Is it "normal" to then be able to peak up the received signal using
> >> the PRESELECTOR control after this tuning procedure?  I don't recall
> >> that being the case in the past, but I can't honestly say that I've
> >> ever checked it.  I follow the prescribed tuning procedure, and go.
> >> For some reason today, I adjusted the preselector some time after
> >> tuning thinking the received signals were kind of low, and discovered
> >> that I could peak them up, but lost about 1/4 to 1/3 of the output
> >> indication.
> >>
> >> Has anyone else observed this on their SR-150, or does the collective
> >> brain trust have any thoughts?
> >>