The philosophy of the day was that that selectivity was desireable and touching up the
tuning every 50 to 100 khz was not a bad thing.  Narrow band was less wideband noise
and adjacent frequency overload interference.



Allison

If its the one i remember it comes from the same era (pre 40ch CB) when 27.235, .265 and
a few other channels were designated as Business CB and carried a slightly different license. 
At that time a Courier BL-100, ML100, Lafeyette had a similar amp, to name a few they were
100W input class AB or AB1 using sweep tubes (6js6 and friends) and for AM ran about
25-30W carrier with clean peaks. There were a few solid state amps and they generally ran
about 75-100W input and were biased for about .2 to as high as .6A no carrier
(single ended and push pull) for linearity.  Most were very clean though the devices of
the time were fragile.

AM and SSB both require a linear amp, only FM and CW can run Class C (back then).

Oh, and there was a lot of crap out there mostly CB rigswith type approved stickers
that were real.  One that came to mind was some of the cheaper radios.  Different
standards then as the 40CH era were also compliant to new standards for
signal cleanliness and adherence to power limits and also the ban on amps that
work above 15 and below 30.

I know this as back then I used my 1st class to cert my brothers commercial setup (legitimate
use for business).  CB wasn't always wild and woolly, and we aren't talking the same thing as now.   
Back then you could be busted for being dirty.  Though there was a lot of angst between CBers
and hams as it wasn't that long before the hams lost 11M.  Despite that there were a lot of hams
that were also legal CBers with calls.


Allison

<<<a BetterQRP end-fed half-wave tuner with an LNR Trail end-fed wire and choke (40/20/10m). Works great, and you get the little LED SWR indicator. Of course>>>

Why?  The match box supplied with it works find for 40/20/10, At least both of mine do.  Of course you still
need different wires for 15 and WARC.


Allison

<Yes - it is generating high power, broad spectrum RF hash.  Mean power output is roughly the same as when it's operating properly.  However, when the RF hash begins, the SWR goes through the roof. >


if there is power out its oscillating.  The problem is it may not be exactly RF.  Most RF power devices
have way more gain at audio and low RF and if the bypassing, grounding, and lead dress is not top notch
they will take off.

I'd definitely use a PAD on the input even if its 1db though more is better. Make sure your grounds are good.
most all RF power amps I do have the edges wrapped with copper and plenty of wires through if there are
no plated through holes.  Especially around the emitter leads.  At 15-20A ground has a habit of looking less so.

Allison

Best answer not said...  Because the manual says don't.



Allison

I have HB SSB radios for 40, 20, 10 and 6M and have worked a lot of DX (even on 6!)
at power levels of 4W and below.

Its doable and can be a lot of fun.  The trick if any is use the best antenna possible.
For example back then It was a 3 element yagi for 6M 18feet up.  When I was working
loads of 10M contacts in early 2011 I used a K6STI rectangle.  A good dipole 30ft up is
a good 20M antenna.

A short vertical with minimal ground plane is not a good antenna its a compromise
and maybe more portable.

In the end its about radiated power, if people can work mobile with 100W with
inefficient (most mobile antennas are) antennas then 5W into a good one is better.

Allison

I've built that and the RF always right to left.  Modulator is on the left (RX mixer) and
TXmixer is on the right(rx product detector).

Its a good design but far from unique.  It's big feature is the high level mixers (ad831s)
are far better than the much cheaper 602s.

I even published a similar design many years back similar using SA602s for lower total power
consumed.

Allison

What WB2WIK said is painfully true.

Minimally a yagi on 6 even three elements or a moxon, for two I'd say not less than 6 elements.
unless your intent is local use out to maybe 30-50 miles.  Aslo even a dipole on 6 has to be rotated
as the pattern at 20FT is actually like the textbooks!

You only need maybe 6 feet between them (more is better) and at least 20ft more like 30+ feet up.
Without question larger and higher is better on both bands.

With 4 elements on 6 at 20W I"m good to about 120miles, at 200W 300 happens.  For 2M I use an
11 element and with 200W it's solidly good to 150+ and often much more.

Since Es season makes any old went noodle usable I often turn the power down to under 5W SSB
to work Europe to make it interesting.  More often though I need more power to be heard over
the pileup din.  Seriously when Es is in a good antenna makes weak ones into strong and also
gives me equal punch in the out going direction for those with tepid antennas.  Also when the Es
are weak or aurora it can make the differs between barely heard and acceptable copy.

I also have a square loop for 6M and a 6 element for 2M as auxiliary antennas for nets and the
difference is remarkable.

Allison

Zenki is only half right.

The manpack boys use power to assure communication between two points.
This is military and lives.  Also the radio that can do 20W is a squad radio,
the rest of the guys may have an VHF/UHF HT in the 5W range.  Also they
are trained to keep it short and to the point even with encryption.

Amateur QRP operation is not based on the idea that contact with HQ from any distance is imperative.
We are amateurs and hobby.  Its fun to play.  Sometime the emergency need occurs and we do
what we have to with what we have often not a KW maybe not even 100W but it gets done.  

So what the military ops do with antennas that look cool but are often very inefficient wideband
without auto tune may or may not apply to hams.  Not to take we can't take a page from them
but our communications are usually to someone/anyone and rarely HQ. I have used PRCs, and
have a PRC1099 (5/20W SSB) and the radio is about 30 pounds with battery and antenna.  Its
heavy and fun.  But I'm not Army humping a 75 pound pack.   It is however worth reading
marine handbook MCRP 3-40.3B (can be found via Google or your favorite search engine)
for field expedient antennas.

If you don't like low power, thanks for playing.  

Seriously, QRP means a weak signal.  I know QRO ops that shun QRP and qrp ops but
willingly chase a rare island into the noise even when the island is less than 100W into a
makeshift antennas. Whats the difference besides attitude.

The 5W number is for contests to level the field so someone that thinks 20W is QRP enough
is not qualified as 5W.  Also 5 W is a convenient point where easily carried low cost batteries
with reasonable lifetimes (hours).  Of course you can run a 100W radio at 20-30W using
very expensive 4s2p Lipo but at some point watthours in the battery will collide with
power out and limit available transmitting time. Also most contests are a day or longer
with field day being a good example.

For some out in the grass, hills, or a picnic bench with a radio its all about what you can
or are willing to carry.  For others its how many QSOs you can run on a lantern battery.  
There are more than a few that do QRP due to conditions at the home
(RFI/HOA/CCR/Line noise) make portable operation a way to play.  

I have no problems working a pileup with 4-5W, good antenna and I just work the the
flow of the pileup and get the contact.  What I can't do even with power is wake a
dead band.


Allison

AA4PB,

I do agree.  However many of the low cost QRP SSB radios have crystal filters
that are tepid at best with 4 crystals and 2.5khz and a shape in the 2.5:1 range
they are only ok at best.  A lot of other rigs deal with this and the receiver does
show that.  The K2 was proof of that, QRP and a killer receiver. 

I've also used the uR2 and uT2 pair with power amp enough to get the basic
boards 1mW up to (4W) it's gobs of fun.  RX is about 75ma, TX well under an amp.
Analog phasing, not a KX3 but still very good.

Then again I have a TenTec Triton (m540) and its your basic 100W solid state but RX
is very good and it only wants 250ma on receive.  Throttled back its' not half bad
QRP radio.

As to antenna, I was asked once if a K1 on a Tribander at 100Ft is QRP?  Of course
and it could both hear and be heard very well.   Regardless of the power you have
or use the very best antenna you can do makes it better.

Of course for run I run QRP mobile 40M using a KNQ7A and a homemade 7.5ft center
loaded whip.  That's doing it the hard way.  It's fun.  That and it's a good minimalist
battery operated 40M radio.

Allison
 

the whole designation of QRP is concerned with output power.

Back in the day a two tube TX (CW) might run nearly 2W heating the tubes (filaments).
Your were 5W or less (input) if the product of the plate voltage and plate current of
the final was 5W or less.  With the right tubes and all it could be done with batteries
and it was!

Now we do QRP with all manor of radios and we look at output power.  

The only time it makes a difference what radio is used is if the whole show runs off battery,
especially if the battery is carried there with all the other gear.  IF I have a short hike
I can bring a 100W Eagle set to 5W and run a few hours on a 25AH gell.  Or I can use
a KX3 and a 3.2Ah LiPo and run the same number of hours and carry 30 pounds less up
the hill. In the end its still 5W and QRP.  And its all good fun.

Oh, and QRP never meant you must use a poor receiver.  So if your willing to carry
a big enough battery almost anything is game, at 5W or less TX power.  Use what
you have or pick what you will use most.   It may make sense to get a 100W radio
for QRP if the trips to the field intermittently and run from the house a lot.  If your
a hiker or  over night pack op maybe a ligheter radio and LiPo batteries are the ticket
for less weight.

In the end and even with 100W no one ever said you have to use it all.


Allison

I went for the TenTec Eagle.  I also have a older (1978 build) TT triton M540, Tempo-One.
The Eagle brough allt he critter comforts like lid filters (auto notch), speech processor, dual VFO
and WARC bands to name a few.

Besides it looks right at home next to my TT 526 6n2.

Allison

Maximum safe load is variable number depending on what your trying to accomplish.

They use 7AH gell sometime 10 or 12AH cells for starting assist depening whos you buy
and the peak current is in the range of 50A or more (at 7-8V).

Generally gell cells can supply peak currents high enough for short periods to melt wires
or terminals.  We are talking 30-100 amps or more for seconds.

So with those two things in mind we have no meaningful "whats the max current" number.
What does happen is the more current you draw the lower the terminal voltage and
you'd like to stay above 11V.  At around 10.4-10/5V the battery is working too hard
or exhausted.  Keep in mind that over discharging the battery is very bad for its life
but brief large current usages generally is not a problem.

What you want to know is run a 100W radio (full or throttled) and for how long?

One caveat you want to keep the total Depth of Discharge (DoD) below 50% for
best battery life (measured in discharge charge cycles).  That mans you can take 5AH
out of a 10Ah battery.

On receive that radio wants an amp maybe 1.5 (give or take) so we are just listening
for around 3.5 hours for less than 50% DOD.   On transmit with no modulation that
radio sits there likely consuming about 2.5A with voice making for 20-23A on peaks
(at 100W).  Since averages are what count we are around 1/3 of the 20-23 A (at 100W)
for the period your transmitting or around 10A (weighted and rounded up).  So that
battery is good for less than 0.5 hour transmit (maybe more) depending.  So if your
total time on of an hour RX (-1.5AH) and 15minutes of transmit (-2.5AH) you have
used around 4AH or about 40% DoD and have some room left.  So the 10AH gell cell
can certainly run full power for short periods of time (minutes at least).  At a more
moderate 25 or 50W that time goes up.  So when you intersperse mostly RX with
short TX operations that little battery can last hours.  Add enough solar power to
offset the RX (20W panel) and that time grows greatly.  A larger panel say 30W
would not only offset the receiver it would also replace some of what the TX used.

A good example is I wanted to demonstrate my new Eagle, 1.3A on RX and 2.5A on no
modulation TX.   At a full 100W it's over 22A on voice peaks.  The battery was a handy
7AH gell cell.  I was able to run RX for over an hour and three 4 minute transmissions
at 50W and the battery was still above 12.5V while receiving.  That was enough for brief
check in to a net.  I don't advise this only it does show what can be done as those gell
cells can deliver a huge amount of current for short periods of time.

NOTE: the assumption is on transmit the no modulation current is 2.5A and at 100W the peak
is around 22-23A take 1/3 of the difference or about 7A and add that back to the 2.5A for around
10A as an average.  It will vary with radio, voice, pauses without speaking, and if compression
is used make the 1/3 average value 2/3 (about 14A).   If you throttle back the TX to 50W
the numbers are better but not twice better as the TX still needs 2.5A to run things and at lower
power the efficiency of the transmitter stages are not as good so the average current does
not drop as fast.  Based on what some of my radios do at 50W the example would only improve
a small amount to maybe an average current of 8A in the first case.

Also the 857 if memory serves has a low power high efficiency 20W mode to help that. 
Check your radios manual on that.

So yes portable ops with a 10AH gell cell are doable and for reasonable times.  However you still
need to replace the power used and charge the battery fully when done if you expect to repeat
that over several days.

FYI: if you discharge that battery to 50% and use a 20W panel (1.2a charge current) you need
no less than 4.1 hours of FULL sunlight on the panel.  That would be hard to do in the winter
and with areas that have trees it may be tough to do.  More solar if you can afford it and carry it
would be better.  Note there are foldable solar arrays but they are very expensive per watt
compared to conventional arrays.


Allison

My $0.02 from building and testing lot of antennas. 

When you used the 6ft length that puts you right next to the antenna holding
the end of the coax via the antenna analyser.  That's nothing like how the
antenna is going to be used.  You become part of the environment and
likely made the antenna tune lower then if you were much further away.

The ugly balun is way to large around.  a 5-6" piece of something is about right
with at least 10-20 turns unless your using something unusually stiff.

Note unless the balun has _very good _choking action the shield of the coax
is part of the radial farm.  A second one close to the entrance is advised.

Usually when a vertical shifts like that it suggests the "ground" isn't.  Add
more radials.

Tune it for the best match at the rig, it s the radio/amp your trying to
make happy.

100Ft of decent coax like quality RG213 isn't enough loss to make a big deal
about when measuring SWR unless the stuff is damaged or bad connectors.
This is HF, if you have more than 1db of loss in the system something is broke.

If you want an RF short (pl259) use a connector and a barrel (DBK female to
connect it) and the connector has a #12 wire from the pin to the shell
(very short, direct!).  A short like that is handy for testing stubs and DC
testing for open cable.  A small dummy load (connector with a short leaded
quality 50 ohm resistor) is handy too.  A clip lead is another word for a crappy
electrically short antenna.

Making the cable a half wavelength is pointless for an antenna that covers at
80 through 10M including 30M and 15M and is more than 50FT away.


Allison

Ok, the usual problem is the shape of the filter.  If you doing the common 4 crystal filter therein
lies the problem.  Those filters if say designed for 2.4KHz to 6db are typically wider than 8khz a
mere 50db down.  yes we are talking shape factors greater than 2 and approaching 3 (ratio of 6db
band width to 60db bandwidth).

Solution use more crystals with maybe more sophisticated filter shape.  I usually start 6 crystals
and have gone as far as 10 to get the steep skirts.  I did do one filter using 5 crystals at 8mhz that
was very good (used very high Q crystals) but it still suffers from fairly weak ultimate rejection
and its in a radio I use for occasional fun.

If the filter has poor skirts or tepid ultimate rejection (most of the 4 crystal fitlers will fail)
then opposing sideband will get by the filter (also happens if the layout or shielding is poor).
Also all of the crystal cases need to be grounded, they are next to each other and can easily
allow unwanted coupling lowering the high rejection skirts to mush.

If you have carrier leaking adjust your balanced modulator (or improve the layout and
shielding of the carrier osc)!

The ARRL press has Experimental Methods in RF Design, EMRFD is very worth having if your
a builder and covers said issues well.


Allison