Swan 350 Loading...
 

I have a silly question about the Swan 350 antenna
loading switch. Did they mean for you to switch it
while the rig was keyed for tuning, or were you
supposed to unkey the rig before switching it?

I've always assumed the later, but...

-Chuck

Swan 350 Loading...
 

Chuck Harris wrote:
I have a silly question about the Swan 350 antenna
loading switch. Did they mean for you to switch it
while the rig was keyed for tuning, or were you
supposed to unkey the rig before switching it?

I've always assumed the later, but...

-Chuck

Chuckee

Silly questions deserve silly answers, no one with any sense buys a Swan.

Do it while you are tuning, if it doesnt smoke you are fine.

Lazy Senior

Swan 350 Loading...
 

Lazy Senior wrote:
Chuck Harris wrote:

I have a silly question about the Swan 350 antenna
loading switch. Did they mean for you to switch it
while the rig was keyed for tuning, or were you
supposed to unkey the rig before switching it?

I've always assumed the later, but...

-Chuck


Chuckee

Silly questions deserve silly answers, no one with any sense buys a Swan.

Who says I bought it?

Do it while you are tuning, if it doesnt smoke you are fine.

I didn't figure you would know.

-Chuck

Swan 350 Loading...
 

Lazy Senior wrote:



Silly questions deserve silly answers, no one with any sense buys a Swan.

Ahem, Lazy, this IS the "boatanchor" forum (and not a personal political
soapbox) where one could expect to ask BA questions, even about a Swan,
without the insults.

-Bill

Swan 350 Loading...
 

Bill wrote:
Lazy Senior wrote:



Silly questions deserve silly answers, no one with any sense buys a Swan.


Ahem, Lazy, this IS the "boatanchor" forum (and not a personal political
soapbox) where one could expect to ask BA questions, even about a Swan,
without the insults.

-Bill


Really, look at some of my posted questions in the last week and the
crap I have gotten from many in this group.


I was simply giving Chuckee what he has been giving me the last week - a
hard time.

Research some of the undeserved crap I have gotten from him.

Lazy Senior

I didnt mean it as an insult tho,no one I know would pay money for a Swan..

Swan 350 Loading...
 

Lazy Senior wrote:



Silly questions deserve silly answers, no one with any sense buys a
Swan.



Ahem, Lazy, this IS the "boatanchor" forum (and not a personal
political soapbox) where one could expect to ask BA questions, even
about a Swan, without the insults.

-Bill

Really, look at some of my posted questions in the last week and the
crap I have gotten from many in this group.

Look at the acrimonious posture you have adopted in this venue in the
past week or two since you 'surfaced'.


I didnt mean it as an insult tho,no one I know would pay money for a Swan..

Ok, I'll buy the part about insults but why in the hell would a real ham
come onto a boatanchor group out of the clear blue and start ragging
guys about buying a Swan?

Tell us which BAs you're running so that we can have as much fun ragging
down your gear. Swan is an easy mark...give us something to get our
teeth into.

-Bill WX4A

Swan 350 Loading...
 

How incredibly rude of "lazy"...I own a 350, love the radio...also own
Icom gear...as for the antenna loading, you need to adjust it while
tuining the radio but with as little power out as possible to save the
finals from going soft on you.

Steve W4SEF


On Wed, 23 Nov 2005 19:26:46 -0500, Chuck Harris
wrote:

I have a silly question about the Swan 350 antenna
loading switch. Did they mean for you to switch it
while the rig was keyed for tuning, or were you
supposed to unkey the rig before switching it?

I've always assumed the later, but...

-Chuck

Swan 350 Loading...
 

Hi Steve,

Thanks for the info. The manual was silent on that issue. I was
concerned that there would be arcing at the switch contacts if
you switched live, so I would try one setting, key it, dip, and
adjust the fine loading, unkey, and then try another coarse load
position, wash rinse repeat... until I got the plate current I
was expecting.

The Swan design was very competent, but very much driven by cost.
That said, it is sort of odd that they used the fancy, but expensive,
7360 balanced modulator tube. I wish they would have used 6146's,
but sweep tubes were so plentiful, powerful, and cheap back then that
they probably were as good of a choice as any.

The drifting problems were the result of Swan's using a single conversion
design. They used a band switched HF VFO to feed their first (and only)
mixer. That decision saved them a whole bank full of crystals, and
another conversion stage. It also reduced the number of conversion
products (spurs) that were drifting around in the cabinet. But the cost
was the introduction of that famous Swan drift to the ham bands.

Another cost reducing measure was to exploit the custom of USB on 20,15,
and 10m, and LSB on 80 and 40m. Swan used hi injection for their mixer
on 80 and 40, and low injection for the rest. That allowed them to get
by with a single BFO crystal, and no USB/LSB switch. Hams didn't like
that, so very quickly, Swan introduced a modification to add a third position
to the REC, CW/SSB switch for "opposite sideband", and added a new crystal.

It's an interesting radio. It won't be my favorite, but I was glad to
get a chance to experience it.

-Chuck


Steve Fritts wrote:
How incredibly rude of "lazy"...I own a 350, love the radio...also own
Icom gear...as for the antenna loading, you need to adjust it while
tuining the radio but with as little power out as possible to save the
finals from going soft on you.

Steve W4SEF


On Wed, 23 Nov 2005 19:26:46 -0500, Chuck Harris
wrote:


I have a silly question about the Swan 350 antenna
loading switch. Did they mean for you to switch it
while the rig was keyed for tuning, or were you
supposed to unkey the rig before switching it?

I've always assumed the later, but...

-Chuck

Swan 350 Loading...
 

Thanks Chuck for the info on Swan. My dad bought me a 350 new in 1965
when I was 15 years old. Loved the radio even tho it did drift. I have
one now and am having a blast working on it to modify and improve the
drift problem that they all had.

73s
Steve W4SEF


On Wed, 23 Nov 2005 19:26:46 -0500, Chuck Harris
wrote:

I have a silly question about the Swan 350 antenna
loading switch. Did they mean for you to switch it
while the rig was keyed for tuning, or were you
supposed to unkey the rig before switching it?

I've always assumed the later, but...

-Chuck

Swan 350 Loading...
 

Steve Fritts wrote:
Thanks Chuck for the info on Swan. My dad bought me a 350 new in 1965
when I was 15 years old. Loved the radio even tho it did drift. I have
one now and am having a blast working on it to modify and improve the
drift problem that they all had.

Swan's answer to the drift problem on the later 350's was to put
the transistor for the VFO (2n706) in a small box mounted under the
chassis. They figured that that would keep it isolated from the tube
heat. The best answer I have found is to turn the radio on at least
one hour before using. That is easily done, as it often takes an hour
of tuning around the bands before you are ready to start transmitting
anyway.

-Chuck

Swan 350 Loading...
 

Chuck Harris wrote:

The Swan design was very competent, but very much driven by cost.
That said, it is sort of odd that they used the fancy, but expensive,
7360 balanced modulator tube.

That's the sheet-beam tube? Those things actually reduced the cost of
a design because they eliminated a whole slew of parts. Later on there
were a bunch of cheap ones designed for chroma detectors in TV sets, but
at first there was only one.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Swan 350 Loading...
 

Scott Dorsey wrote:
Chuck Harris wrote:

The Swan design was very competent, but very much driven by cost.
That said, it is sort of odd that they used the fancy, but expensive,
7360 balanced modulator tube.


That's the sheet-beam tube? Those things actually reduced the cost of
a design because they eliminated a whole slew of parts. Later on there
were a bunch of cheap ones designed for chroma detectors in TV sets, but
at first there was only one.
--scott


I've only heard of them being used because of their extremely good
carrier suppression. They provide on the order of 60dB of carrier
suppression, as compared to a typical balanced modulator which gives
only 30dB. When used in conjunction with a crystal, or mechanical
filter, the 7360 can achieve 80dB of carrier suppression.

I can see that they would provide some reduction in parts, they are
capable of oscillating, but Swan didn't use it that way. I think
they could have achieved a greater cost savings using 4 matched
diodes in a ring modulator configuration.

-Chuck

Swan 350 Loading...
 

it is sort of odd that they used the fancy, but expensive,
7360 balanced modulator tube.

That was an extremely common choice for not only for not only
transmitter balanced modulators but also for receiver mixers and
product detectors in the 50's and 60's. I think it must've been the
case that one early ham article used it and everyone else copied it.
Certainly it was not a common junkbox part...

Tim.

Swan 350 Loading...
 

Swan 350 Loading...
 

In article ,
Chuck Harris wrote:

ARRL published a circuit using it in many of their handbooks from the
'60s. And I have heard that it was used in TV applications, but the
part that surprises me is I have only seen one type, the 7360. If it
was such a commonly used tube, it surely would exist in a non industrial
numbered version (eg. 6ZZ9, or some such).

Chuck,
There was never a pin-for-pin "entertainment" version of the 7360,
but there were a few functionally-equivalent types, the 6AR8, 6JH8,
and maybe another (6M-something) I can't remember. They could be
used in the same circuits as the 7360, and they were cheaper
as they were made in much larger numbers (Zenith used the 6JH8 in
color-TV demodulator circuits). And they were used in ham gear
too -- my old Swan 260 "Cygnet" used a 6JH8 as the balanced mod.
These tubes did make great balanced modulators, and nice receiver
mixers too.

Ted Zateslo, W1XO

Swan 350 Loading...
 

Ted Zateslo wrote:
In article ,
Chuck Harris wrote:

ARRL published a circuit using it in many of their handbooks from the
'60s. And I have heard that it was used in TV applications, but the
part that surprises me is I have only seen one type, the 7360. If it
was such a commonly used tube, it surely would exist in a non industrial
numbered version (eg. 6ZZ9, or some such).


Chuck,
There was never a pin-for-pin "entertainment" version of the 7360,
but there were a few functionally-equivalent types, the 6AR8, 6JH8,
and maybe another (6M-something) I can't remember. They could be
used in the same circuits as the 7360, and they were cheaper
as they were made in much larger numbers (Zenith used the 6JH8 in
color-TV demodulator circuits). And they were used in ham gear
too -- my old Swan 260 "Cygnet" used a 6JH8 as the balanced mod.
These tubes did make great balanced modulators, and nice receiver
mixers too.

Ted Zateslo, W1XO

Hi Ted,

Thanks for the info. I thought I knew my old RCA RC-25 tube manual
pretty well; I bought it new, and the binding has all fallen apart,
but there they were just like you said.

I must have stopped mucking around with tube color tv's before they
became popular.

-Chuck

Swan 350 Loading...
 

[7360 tubes for balanced modulators and mixers]
Chuck wrote:
ARRL published a circuit using it in many of their
handbooks from the '60s.

I just pulled out my '65 ARRL handbook and there are two SSB exciters,
each of which uses TWO 7360's.

And there are two not-awfully-fancy receivers, each of which uses a
7360 in the mixer.

Man, somebody in the ARRL must've owned stock in that tube company :-).

Tim.