On Mar 25, 1:41*am, Michael Black wrote:
On Mon, 24 Mar 2008, Tim Shoppa wrote:

QST for May 1965 has the "Miser's Dream" that was a pretty advanced
receiver for the time, including a 7360 mixer and an HF IF filter (though
a second conversion to 455KHz for specific design reasons).

The article is called "Some Thoughts on Home Receiver Design". The
second
conversion to 455 kc. was to avoid having the BFO on the lots-of-gain
IF, and to
permit the use of a crystal controlled BFO, yet have it be adjustable
by moving
the 2215-to-455 oscillator freq.

The first IF is 2215 kc. If you can find a junked Sierra 126B
selective voltmeter,
it has nearly-identical filters inside. Some other models of Sierra
selective voltmeter
may have them too.

*I've
always considered that the vector for the 7360 in hobby receiver
mixers, though if I dug out the article, I'm sure it explicitly
referenced the Squires article.

The Squires article was in Sept. 1963 QST.

*One feature of the receiver is
a q-multiplier at the signal frequency, to improve front end
selectivity given there was no RF amplifier. *I've always wondered
how necessary that q-multiplier was, given later receivers with
high IFs got by fine with limited front end selectivity (I always
wondered if the notion of no RF amplifier was so radical that
they felt a need for the q-multiplier).

It was necessary on the higher bands. The IF was only 2215 kc., and on
15 meters the image rejection wasn't too good with just a single tuned
circuit.
The quick solution was an RF Q multiplier. But it seems to me to be an
add-on;
what it does is to boost the desired signal by increasing the
effective Q, rather
than rejecting the unwanted by adding more poles.

IMHO the better solution would be a double-tuned input circuit.

There was a tube receiver in QST about February of 1973 (or was
it '72?), that had to be one of the last described there. *It went
for super strong signal handling, including a 7360 mixer and some
sort of power tube as the RF stage.

"An Experimental Receiver For 75 Meter DX Work", by W1KLK, February
1972.
Uses a 7044 computer duotriode as a grounded-grid RF amp, followed by
a 7360 mixer.
There are no less than four tuned circuits before the mixer, and you
have to retune the
preselector often. Not for idle bandscanning; this RX is for digging
out the weak ones.

The 6AR8 is reportedly microphonic, and other types are preferable.
7360 was considered
a transmitting tube, which is why you find it in the Transmitting Tube
manual, and why
almost nobody but RCA made them.

Alternatives are the 6JH8 and 6ME8, which are less expensive and more
common. They were
used in TV sets. At least one ham rig maker (Swan) changed from using
the 7360 as a
balanced modulator to the 6JH8.

The Southgate Type 7 receiver section uses a 7360 mixer (google my
call to see).

73 de Jim, N2EY

Hi,

snip

Alternatives are the 6JH8 and 6ME8, which are less expensive and more
common.

I've done some experiments with the 6ME8 and it's horribly noisy compared
to the 7360.... or even a 6BE6 for that matter :-\

Cheers,
__
Gregg

On Thu, 1 May 2008, geek wrote:

Hi,

snip

Alternatives are the 6JH8 and 6ME8, which are less expensive and more
common.

I've done some experiments with the 6ME8 and it's horribly noisy compared
to the 7360.... or even a 6BE6 for that matter :-\

You're not going to get a balanced mixer out of a single 6BE6 either.

But, on does have the advantage that beam deflection tubes aren't just
used as first mixers. Balanced modulators and mixers in SSB transmitters.
Product detector in a receiver. There, noise isn't the same issue
as in a first mixer.

Michael VE2BVW

On Thu, 01 May 2008 11:25:12 -0400, Michael Black wrote:

On Thu, 1 May 2008, geek wrote:

Hi,

snip

Alternatives are the 6JH8 and 6ME8, which are less expensive and more
common.

I've done some experiments with the 6ME8 and it's horribly noisy compared
to the 7360.... or even a 6BE6 for that matter :-\

You're not going to get a balanced mixer out of a single 6BE6 either.

But, on does have the advantage that beam deflection tubes aren't just
used as first mixers. Balanced modulators and mixers in SSB transmitters.
Product detector in a receiver. There, noise isn't the same issue
as in a first mixer.

Michael VE2BVW

Indeed!

My tests were based on the first mixer for a SW receiver (gah, which I
have still to build . )

Cheers!
__
Gregg