Bob wrote:
ken scharf wrote:

Sounds like you're building a receiver with only one tube in it (a 7360)
and everything else solid state. Then again the 7360 probably makes a
very good product detector too.

No - the RF amplifier stage is a variable mu pentode, and there are more
variable mu valves used in the IF, another 7360 for the product detector,
and the rest is solid state. The hybrid approach seemed best - for
example, the variable current drawn by the audio stages is /entirely/
isolated from the IF supply, the front end supply and the local oscillator
supply. At the moment, it's a single conversion superhet, with a 10.7 MHz
IF (because I have 10.7 MHz filters), though I'm considering making it dual
conversion, with a very high first IF, to improve the inherent image
problems.

C.

One project that I have been considering would be a re-creation of the
classic Drake 2B receiver. This receiver was a dual conversion 80 meter
receiver with an additional converter for other bands (making it a
triple conversion). The receiver covered 600khz of the 80 meter band
(3.5-4.1 mhz), the first IF was 455 khz, and the second IF was 50 khz.
I have several sets of IF cans from BC453 receivers (85khz) and a 2.7
khz Collins filter that could be used instead of an IF transformer for
the first IF.

I was thinking of using compactrons in the set, a single 6AR11 for the
85 khz IF, a 6D10 for the product detector and bfo, a 6AF11 for the AF
stage and S meter amp. A 6AG11 would serve as an AGC tube and AM
detector. The second (third?) mixer would be a 6BE6 (455-85), the
first and second mixers would be 7360's (expensive!). The first (xtal)
hfo would be solid state (maybe a pll), the second hfo (vfo) would also
be solid state. I have several nice three gang capacitors from ARC-5
receivers with dial gear drive that would work nicely. The completed
set would look more like the 2C because of the dial unless I ever find
another Edystone dial. (I had one in the junk box for a few years and
sold it on ebay to someone building an HBR. Got a kings ransom for it too).

"ken scharf" wrote in message
. ..
Bob wrote:
I was thinking of using compactrons in the set, a single 6AR11 for the
85 khz IF, a 6D10 for the product detector and bfo, a 6AF11 for the AF
stage and S meter amp. A 6AG11 would serve as an AGC tube and AM
detector. The second (third?) mixer would be a 6BE6 (455-85), the first
and second mixers would be 7360's (expensive!). The first (xtal) hfo
would be solid state (maybe a pll), the second hfo (vfo) would also be
solid state. I have several nice three gang capacitors from ARC-5
receivers with dial gear drive that would work nicely. The completed set
would look more like the 2C because of the dial unless I ever find another
Edystone dial. (I had one in the junk box for a few years and sold it on
ebay to someone building an HBR. Got a kings ransom for it too).

The 6JH8 should work as well as the 7360 in a receiver mixer.
Swan changed to the 6JH8, probably for cost reasons.
( http://members.shaw.ca/pacifictv/cartridg.htm )

Not to make you feel bad, Ken... But, I still have an Eddystone
squirreled away for my HBR project. I think the Drake 2C
version makes more sense, though. The plug in coils and
oscillator LO scheme used by W6TC in the HBR
series leaves a bit to be desired.

Pete

Tio Pedro wrote:
"ken scharf" wrote in message
. ..
Bob wrote:
I was thinking of using compactrons in the set, a single 6AR11 for the
85 khz IF, a 6D10 for the product detector and bfo, a 6AF11 for the AF
stage and S meter amp. A 6AG11 would serve as an AGC tube and AM
detector. The second (third?) mixer would be a 6BE6 (455-85), the first
and second mixers would be 7360's (expensive!). The first (xtal) hfo
would be solid state (maybe a pll), the second hfo (vfo) would also be
solid state. I have several nice three gang capacitors from ARC-5
receivers with dial gear drive that would work nicely. The completed set
would look more like the 2C because of the dial unless I ever find another
Edystone dial. (I had one in the junk box for a few years and sold it on
ebay to someone building an HBR. Got a kings ransom for it too).

The 6JH8 should work as well as the 7360 in a receiver mixer.
Swan changed to the 6JH8, probably for cost reasons.
( http://members.shaw.ca/pacifictv/cartridg.htm )

Not to make you feel bad, Ken... But, I still have an Eddystone
squirreled away for my HBR project. I think the Drake 2C
version makes more sense, though. The plug in coils and
oscillator LO scheme used by W6TC in the HBR
series leaves a bit to be desired.

Pete


Well the plug in coil stock used by W6TC are also unobtainium these days
too. It IS possible to by raw polystyrene tubing of the right size, and
glue onto bases from dead tubes, or tube base plugs (both of which are
available from time to time). The APC variable caps are getting rare
these days, but good quality ceramic trimmers would sub and these are
not TOO hard to find.

I have a bunch of turret tv tuners with the removable strips and also
gave thought to building a receiver similar to the HBR's but with toroid
core coils switched in the tuner strips. I don't know if the toroid
cores were available to W6TC and if he would have used them.

I also have a dial drive from an HRO receiver if I ever get the desire
to build something even more antedeluvian!

"ken scharf" wrote in message
. ..
Tio Pedro wrote:
"ken scharf" wrote in Well the plug
in coil stock used by W6TC are also unobtainium these days
too. It IS possible to by raw polystyrene tubing of the right size, and
glue onto bases from dead tubes, or tube base plugs (both of which are
available from time to time). The APC variable caps are getting rare
these days, but good quality ceramic trimmers would sub and these are not
TOO hard to find.


The APC caps (silver plated brass are needed for the LO coils) are
still available. I've read that over one million a month were produced
during WWII. How true that is, I don't know, but it was on a webpage
dedicated to the history of Hammarlund. You have to shop around,
but I've picked up a few dozen for around two bucks each.

The National polystrene coils were becoming scarce by the time
the last HBR ran in QST. Bill (exray) uses Garolite XXX tubing
(phenolic) for his plug in coils; a bit pricy for my tastes. Ted's
coils had Qs of around 150 or so.

I'm going to try using fiberglass tubing--fortunately I have the
poor ham's Q-meter (Heath QM-1) to verify the effectiveness of that
material. A kind soul sent me a few dozen expired tubes to salvage
the bases from. There's always plastic pill bottles, they've been
tried and pass the Q-Meter test.

I have a bunch of turret tv tuners with the removable strips and also gave
thought to building a receiver similar to the HBR's but with toroid core
coils switched in the tuner strips. I don't know if the toroid cores were
available to W6TC and if he would have used them.

W6TC went through great pains to eliminate drift in the LO coils,
I don't know if toroids are the best choice for oscillator coils.

I'm sure you're familiar with the turret tuner in the RCA
TW-2000?

I also have a dial drive from an HRO receiver if I ever get the desire to
build something even more antedeluvian!

Now you're talking!!

Pete

Tio Pedro wrote:
The National polystrene coils were becoming scarce by the time
the last HBR ran in QST. Bill (exray) uses Garolite XXX tubing
(phenolic) for his plug in coils; a bit pricy for my tastes. Ted's
coils had Qs of around 150 or so.


I remember Allied radio and Lafayette radio both carrying those
polystyrene coil forms as late as the early 70's (The last HBR article
was in '64 IIRC). Those coil forms were NOT made by National Radio, the
National coil forms were made of dark brown plastic (bakelite?) or
ceramic material. Millen also made some plug in coils that were made of
an orange colored bakelite like material. The '67 HB had a novice
transmitter (1625 final) that used those coil forms, Allied Radio part
numbers given.

I had a few of those coil forms at one time purchased to build a one
tube regenerative receiver from the 'boy electrician' book by Alfred
Morgan. Barry electronics had the 1H4G tubes for 50 cents back then.

Ocean State Electronics was carrying the polystyrene coil forms a few
years ago. They also had some 'cloned' forms that would fit the old
National Radio SW3 receiver (same weird 6 pin base).

Tio Pedro wrote:

The 6JH8 should work as well as the 7360 in a receiver mixer.
Swan changed to the 6JH8, probably for cost reasons.
( http://members.shaw.ca/pacifictv/cartridg.htm )

I've tried both, and the 7360 wins by a long way - it probably proves
that "you get what you pay for"! The 7360 gave me useful conversion gain,
a spectacularly high intercept, and as low a noise figure as you could ever
wish for.

Bob

On Sep 21, 2:30�pm, Bob wrote:
Tio Pedro wrote:
The 6JH8 should work as well as the 7360 in a receiver mixer.
Swan changed to the 6JH8, probably for cost reasons.
( �http://members.shaw.ca/pacifictv/cartridg.htm)

That's true, but the Swan transceivers weren't using the 7360 as a
receiving mixer. They were using it as the balanced modulator in the
transmitter section, which is a very different job, and the 6JH8 was a
low-cost alternative.

The 6JH8 could probably be used (with mods) in a lot of SSB
transmitter projects from the hollowstate era, rather than the 7360.

I've tried both, and the 7360 wins by a long way - it
probably proves
that "you get what you pay for"! �The 7360 gave me
useful conversion gain,
a spectacularly high intercept, and as low a noise figure
as you could ever
wish for.

What circuit and values did you use, Bob? Voltages, balanced vs.
unbalanced, output and input circuits, etc.?

73 de Jim, N2EY

wrote:
On Sep 21, 2:30�pm, Bob wrote:
Tio Pedro wrote:
The 6JH8 should work as well as the 7360 in a receiver mixer.
Swan changed to the 6JH8, probably for cost reasons.
( �http://members.shaw.ca/pacifictv/cartridg.htm)

That's true, but the Swan transceivers weren't using the 7360 as a
receiving mixer. They were using it as the balanced modulator in the
transmitter section, which is a very different job, and the 6JH8 was a
low-cost alternative.

The 6JH8 could probably be used (with mods) in a lot of SSB
transmitter projects from the hollowstate era, rather than the 7360.

I've tried both, and the 7360 wins by a long way - it
probably proves
that "you get what you pay for"! �The 7360 gave me
useful conversion gain,
a spectacularly high intercept, and as low a noise figure
as you could ever
wish for.

What circuit and values did you use, Bob? Voltages, balanced vs.
unbalanced, output and input circuits, etc.?

73 de Jim, N2EY
Just looked on bay.
Wow, the 7360 is as expensive as 1L6's!

wrote:

What circuit and values did you use, Bob? Voltages, balanced vs.
unbalanced, output and input circuits, etc.?

Balanced throughout! Supply is 130 V, and the deflection plates have a 10 k
preset (to give DC balance) with the wiper going to the supply, and the
ends connected to potential dividers (68 k and 10 k) to give 15 V at pins 8
and 9. The anodes are connected directly to the primary of a 10.7 MHz IF
transformer, with the centre tap of the transformer going to the positive
rail through a 220 ohm resistor. There is a fixed capacitor (of 100 pF)
from one anode to ground, and the other anode has a parallel combination of
68 pF fixed and a 65 pF trimmer to ground to allow phase balance. Pin 3
(grid 1) has - 1.9 V bias fed through a 470 k resistor and is coupled to
the top of an at-frequency tuned circuit - the high input impedance of the
valve allows the tuned circuit to be connected without a tap. The bias
line has to be well-decoupled (I used a 470 uF electrolytic) to prevent
hum. The control grid (pin 2) is connected to the positive supply through a
470 ohm resistor, and is decoupled to ground with 10 nF.

The balanced local oscillator (a pair of 2N3819 FETs) is buffered by a pair
of common emitter bipolar transistor stages (I used 2N3866, because I have
a lot of them) and fed to the deflection plates in antiphase. IF rejection
is roughly 60 dB, conversion gain is 25 dB. You can tune right through the
IF frequency /without/ /a/ /whistle/ - which is unique in my experience!

I found the circuit values in the original valve specification, and they
seem to be well optimised - I tried various alterations, but always to the
detriment of performance.

The Kallitron oscillator is stabilised (in 10 Hz steps) with a huff-and-puff
unit based on a PIC, which also provides a frequency readout on an LCD
display.

Over the years, I've tried /every/ possible mixer topology, including the
modern H-mode switching types (which are astonishingly good), but the 7360
can't be beaten.

The receiver is simply the best that I've ever used, even including some of
the high-priced exotica that I saw and used at the BBC Caversham Monitoring
department!

Bob

"Bob" wrote in message
...
wrote:
Over the years, I've tried /every/ possible mixer topology, including
the
modern H-mode switching types (which are astonishingly good), but the 7360
can't be beaten.

Bob

Hi Bob

A lot of folks have reported good results using the 6JH8 in place
of the 7360; with a few reporting better linearity. They appear
to be pretty much the same as far as performance. Have you tried
one?

Pete