--- In ham_amplifiers@..., "Phil Clements" <philc@...>
wrote:

I already had a monster blower on hand when I put my YC-156 amp
together. I drilled a hole in the wall, and ran the cooling air
thtough a 10 foot hose from another room. I hear no more noise

than

the cooling fan on my PC makes here in the ham shack.

### I learn something new every day ! I never tried remoting a
blower. I had been told that a lot of the noise was from the
actual airflow through the tube itself, so never tried it.

### Never had any problem remoting the RF deck/Hv supply either...
since we can see the wattmeters in both places... and easily tune
the amp in the other room. With variable 0 to -10 vdc in the
remote location... fed back to the ALC jack on the xcvr... and a
footswitch/wattmeter in both locations... it's easy to tune the amp
up. Just run into another room... adjust drive level... tweak
it... once the numbers are all written down, it's a moot point
anyway.... just change bands and dial by the numbers.

My shack is really small 8 x 10 x 7.5' ceiling. ...... the
concern with a remote blower would be cooking the shack with too
much hot air !!! ... even in winter.

### with a bigger room.... I can see the merits of a remote blower
[s]. With the entire amp remoted.... in summer time, one can
exhaust the hot air outside.... and in winter, exhaust to the
inside.

later... Jim VE7RF

(((73)))
Phil, K5PC

Alternative topologies, and using higher voltage devices make things
much easier. Common-emitter can be troublesome. We ended up going
common-drain (simple source followers), running 28V, and using a
diff-amp as the voltage gain stage, then resistive feedback to the
input stage. So, the feedback was DC to 100MHz or so. Ended up with
about 150W capability and IMD3 measured -58dBc rel one carrier. 5ths
and higher order were down substantially more.

We had tried simple xfmr feedback, problem was that the 2nd/4th/6th
order products, down near DC, were re-mixing with fundamentals to
create 3/5/7, etc. Weren't able to make xfmrs that operated close
enough to DC to get around that prob.

We worked with the semi mfr as well, trying to get internal resistors.
Turns out the technology used for emitter ballasting is fundamentally
non-linear. Good for balancing DC idle currents, but not very good
for negative feedback. In the MRF150 type devices, no such ballasting
is used, rather they depend on having 32 identical devices adjacent to
each other on a wafer, and bonding in direct parallel. Semiconductor
physics allows you to do things like that, expect adjacent devices to
be identical enough to directly parallel. In the MRF154, which was 4
X MRF150 in a single package, the drains and sources were in direct
parallel, and the only isolation resistors were in the gate paths,
cutting down on some form of cross-coupled VHF oscillation between
devices.

At one point, we feared we'd have an expensive hybrid design facing
us, but coming up with the diff-amp input, two stage buffer and final
output FETs, and getting the customer to buy off on 28V operation, did
the job. Complex circuit when we were done, and way more gain than
you want usually from a single stage, but we got the performance
without a custom hybrid design.

Hard to believe I was once in that industry...this was shore-based
marine SSB, we were supposed to meet a final system IMD of 36dBc rel
one carrier, including all stages...so we made them all super-clean,
and beat the spec by 10dB. Adjacent channel power measured far down
as well, but I don't recall the figure.

Actual torture test was to put band-limited white noise through it,
and see how much energy was in the next adjacent channel. A variation
on that test is still in use commercially, known as the "noise power
ratio" test.

Z

--- In ham_amplifiers@..., FRANCIS CARCIA <carcia@...> wrote:

I suspect you would be better off with a 300 watt amplifier running

closer to class A with transformer feed back, Most RF transistors have
internal emitter resistors to balance the parallel cells. Making
feedback work over a wide frequency range takes real talent and good
pc board layouts. gfz

zerobeat40 <zerobeat40@...> wrote: Hey, I tried to put the

NFB into a solid state amp once, being used as

a driver for commercial HF SSB. It was not so easy.

Assuming a pair of NPN transistors delivering 100 watts at 30MHz,
running from 13.8VDC, producting -30dBc IMD that we want to improve by
about 10dB. The correct value resistor is approx 0.2 ohms and it must
dissipate 15 watts, if the amp is to survive clumsy tuning into an
antenna tuner at full power. You could get away with a 5 watt device
if you insisted on only SSB (no CW or FM) and only into a matched
load. Smallest resistor I was able to find to meet this was a chip
style component, about 1/2 inch X 1/2 inch. It measured 5nH of
inductance. At 30MHz, XL=nearly one ohm. The stage gain at 30MHz was
reduced to approx 2dB, and the phase shift of this inductance reduced
the IMD benefits of the NFB to having no IMD reduction at all. At
1MHz, the solution worked very nicely - stage gain stabilized at 14dB,
and IMD measured about -42dBc (referenced to either of two incident
carriers)

If you could somehow create a 15 watt resistor that is 0.2 ohms and
under approx 0.2nH of inductance, then your proposed solution will work.

Let us know when you find that resistor.

Z

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

tnx, Tony. Since adding RF-NFB to a transistor amplifier is as
simple as adding unbypassed R to the emitter leads, it puzzles me why
Ham transceiver manufacturers don't wake up and start building
pristine radios.

Since the TS-830S uses essentially a copy of the KWM-2's RF
amplifier, it isn't surprising that the 830 has a reputation for
cleanliness.

cheerz

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

On Oct 30, 2006, at 5:14 PM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...>

wrote:

### what have u got against HV fuses Rich?

RICH SEZ.... Do you carry two spare tires in your car? As I

see

it, overkill is not good engineering - except perhaps on a

moon

mission if I going.

### RL Drake used a .82 ohm 1 watt reistor in the B+ as a HV
fuse.... it always blows

RICH SEZ.... It is not a fuse at 2500v, it was a temporary metal

vapor arc that had a v-drop of c. 20v during the period when it
should have been limiting current.

#### Rich, obviously a .82 ohm resistor is not gonna limit
current. It's in there as a HV fuse.. that's it.... and easily
replaced...

You missed the point: A fuse that creates a metal vapour arc when

it opens does not adequately limit peak-I until the arc is

extinguished. This is why 250v 3AG fuses are bad engineering
practice when used in a several kV application.

### They STILL open faster than any 240 Vac breaker ever will !

### The sand filled HV fuse's [5" long] kill that vapour arc so
fast, it's unreal. ... not even an issue.



### There is Nothing wrong with using a 250v 3Agc fuse/fuseholder
in the CATHODE of a linear either [in the CT of the fil xfmr]....
just shunt the 3agc fuse holder with a 100 K - 2/3 watt MOF
resistor. Put some 6A diodes [6A10, 1 kv-400A surge] back to
back, installed between chassis and B- IF the cathode fuse
blows open... you still have the 100 K resistor across it... which
biases the tube off ! Works slick..... and every time too.

...

RICH SEZ....The Henry 2k-4 has a resonant-choke filter --

perfect

for 120v operation with virtually no drop in PEP out.

### Trbl is... you would have to run a new heavy duty 20-

30 A 120 V line into the shack to run a Henry 2K-4.. on 120 V.

RICH SEZ... Not true. They run FB on SSB from a 120v, 15a

circuit.

####### DREAM ON !! 120v x 15 A = 1800 va To calculate AC
mains VA.... take the DC input in watts and multiply x 1.22

[this

factor's in 10% for core losses.. and another 11% for power
factor]

RICH SEZ.... The duty-cycle of 2-way SSB is under 20%. The old

Plywood Box amplifier did 14 out on SSB and it did not trip the
40a, 240v breaker.

### Not a chance ! Duty cycle on ssb is damned near 50%..
looking at any plate current meter. Rich, with ur 100' run of
4 ga CU wire... and an undersized 65 lb dahl xfmr.. and a 40A
breaker.... there is NO way you could run it key down for 1-3
seconds... just to take some steady state plate/grid cuurent
readings. Ur telling me b4 ur plate V was dropping 1000 V, while
talking.... what is it with dead cxr... 2 kv ??? You will never
know with a 40A breaker. You would be drawing an easy 110 AMPS
with 14 kw out ! Rich, if you can't possibly measure steady
state plate current..... you have nothing to reference ur average
plate current to, during typ ssb.

### IMO... using a scope to measure power out is flawed. IF the
scope is out say 5%.... ur calculated power output will be out
10%. [using V squared /R] In any event, the scope leads will
exhibit swr, and other bugs.


Later... Jim VE7RF

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

Jim...

pentalab wrote:

--- In ham_amplifiers@..., Jan Erik Holm <sm2ekm@...> wrote:

Well right now I dont have any "official test lab" figures,
however W8JI has measured (if you trust him, I do in this
case) -47 dB.

### W8JI, ALSO claimed in the same sentence, -52db for a Drake T4XC ! <snip>

There is NO mention of Drake or T4XC on that entire web page that I posted the quote from <>. It just ain't there.

73, Tony W4ZT

--- In ham_amplifiers@..., Jan Erik Holm <sm2ekm@...>
wrote:

Well right now I dont have any "official test lab" figures,
however W8JI has measured (if you trust him, I do in this
case) -47 dB.

### W8JI, ALSO claimed in the same sentence, -52db for a Drake
T4XC ! I owned 4 of em yrs ago... and I got the same results as
the ARRL lab did... a paltry -30 db pep... or just -26db compared
to one tone... which is typ of sweep tubes. Even to get that,
Drake used 70 ma of zsac @ almost 700 Vdc.... so the idle POWER
on the pair of sweep tubes was = 99% of the rated plate
dissipation !

### What power level did u run the FT-1000D tests at ?? I
currently have 2 x FT-1000D's.... and 2 x FT-1000MP-MK-V's.
haven't measured any of em. Seems to me the arrl lab measured -
36db PEP when then 1000-d was run full bore at 200 w out.
Yaesu claimed -36db, compared to ONE tone [-42 db pep], when run
at 150w out.

### Would be interesting to know what the 1000-D is at say 100
w output ? I'm betting it's very good.

### also... did u drive it into ALC ??? Try setting the power
output at 200 w.... but only driving it to say 190w [no alc]
and then at 150w.... and again at 100 w ..... all the while the
power output control is sitting at 200w.... and no alc ever
showing in any case. Then try it with alc at top of it range.

### Beware,,, my 2 x FT-1000D's new, were totally out of
calibration on every thing...esp alc. Srvc manual sez between no
alc.. and max alc... should be a 9.7 db difference..... mine was
only 5.2 db. {which is better imo... since hams will wail away on
the ALC]

### Also try adjusting the bias pot. I think the normal idle on a
1000-D is just 1 amp. Tweak it up to 1.5 A.... and also 2.0
A... and re-run ur tests.... u will be surprised.

### On the MK-V.... you can adjust EACH transistor
independently.... ditto with the driver transistors.... and you
do all of this TWICE.... once for AB... and again for CLASS A.

### On AB.. idle is 1 A PER final transistor 2A total. On Class
A... it's a whopping 5 A PER transistor... and 10 A total.

### On the MK-V hidden menu 9-XXX... you can also adjust
the "drive" on a band per band basis... most of em are way too
high. On CW... reducing em a bit, will eliminate the key clix.

### To eliminate ALC overshoot on all these rigs... you can
[ssb/cw] apply external -DCV to the ALC jack. You can also
just limit the audio on ssb with external rack mount
compressor's/limiter's/ distortion cancelled audio clippers. That
way, I can achieve an easy 1500w with NO alc ever showing at
all... if u wanted.

R L Measures wrote:

what Ham transceiver will allow testing of IMD below –40db?

### The yaesu MK-V on Class A... depending on BAND... is -60db
for 3rds... and -75db for 5ths. You can hear the diff on a 2nd
RX 3' away. I can also hear the difference from 1200 miles away
[IF the other station is running barefoot, no linear]

Later... Jim VE7RF

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

I suspect you would be better off with a 300 watt amplifier running closer to class A with transformer feed back, Most RF transistors have internal emitter resistors to balance the parallel cells. Making feedback work over a wide frequency range takes real talent and good pc board layouts. gfz

zerobeat40 wrote:

Hey, I tried to put the NFB into a solid state amp once, being used as
a driver for commercial HF SSB. It was not so easy.

Assuming a pair of NPN transistors delivering 100 watts at 30MHz,
running from 13.8VDC, producting -30dBc IMD that we want to improve by
about 10dB. The correct value resistor is approx 0.2 ohms and it must
dissipate 15 watts, if the amp is to survive clumsy tuning into an
antenna tuner at full power. You could get away with a 5 watt device
if you insisted on only SSB (no CW or FM) and only into a matched
load. Smallest resistor I was able to find to meet this was a chip
style component, about 1/2 inch X 1/2 inch. It measured 5nH of
inductance. At 30MHz, XL=nearly one ohm. The stage gain at 30MHz was
reduced to approx 2dB, and the phase shift of this inductance reduced
the IMD benefits of the NFB to having no IMD reduction at all. At
1MHz, the solution worked very nicely - stage gain stabilized at 14dB,
and IMD measured about -42dBc (referenced to either of two incident
carriers)

If you could somehow create a 15 watt resistor that is 0.2 ohms and
under approx 0.2nH of inductance, then your proposed solution will work.

Let us know when you find that resistor.

Z

tnx, Tony. Since adding RF-NFB to a transistor amplifier is as simple as adding unbypassed R to the emitter leads, it puzzles me why Ham transceiver manufacturers don't wake up and start building pristine radios.

Since the TS-830S uses essentially a copy of the KWM-2's RF amplifier, it isn't surprising that the 830 has a reputation for cleanliness.

cheerz

On Oct 31, 2006, at 7:32 AM, Tony King - W4ZT wrote:

R L Measures wrote:

What is the total IMD of a KWM-2 ?

<snip>

Tom says the following:
"IM3 levels of -30 dB are really very poor. An old KWM2 I tested was -47
dB using ARRL standards. Compared to something like an IC-756, the
Collins had about 50 times LESS power in total adjacent channel
distortion products!"
<>

73, Tony W4ZT

.

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

R L Measures wrote:

What is the total IMD of a KWM-2 ?

<snip>

Tom says the following:
"IM3 levels of -30 dB are really very poor. An old KWM2 I tested was -47 dB using ARRL standards. Compared to something like an IC-756, the Collins had about 50 times LESS power in total adjacent channel distortion products!"
<>

73, Tony W4ZT

Well right now I dont have any "official test lab" figures,
however W8JI has measured (if you trust him, I do in this
case) -47 dB.

Myself I have measured a KWM-2 compared to a FT-1000D, KWM-2
was almost 15 dB better, you can see here



I have a faint memory that Ive read someplace -56 dB however I dont
remember more.

In any case I think its safe to say that a KWM-2 is far better then -40 dB, or a 32S-3 for that matter.

73 Jim SM2EKM
-----------------------------------------------------------------------------
R L Measures wrote:

What is the total IMD of a KWM-2 ?

On Oct 30, 2006, at 9:25 PM, Jan Erik Holm wrote:

As far as I know a Collins KWM-2

/ SM2EKM
-------------
R L Measures wrote:

what Ham transceiver will allow testing of IMD below –40db?

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

开云体育

As far as I know a Collins KWM-2

/ SM2EKM
-------------
R L Measures wrote:

If I recall, they have the QRO brand of amps set up this way, or I
seen one being modified I can't remember which. All they did was
mount a button type thermostat near the tube. Seems to me though they
used a single speed blower and used a resistor in series with the
line lead. The thermostat simply shorted out the resistor when it go
hot enough to close.

If it were me, I'd mount a small heatsink on the thermostat to catch
the hot air transfering it to the metal end of the thermostat. Maybe
make one from thin copper sheet (valley copper). One for a small
power transistor mounted on the metal end of the button would do it
and mount either near or in the heated air flow of the tube. You
would want a N/O type contact on the thermostat. You can buy these at
Granger for practically nothing along with the blower. The resistor
was a power resistor, maybe 25 watt, but I can't remember the value,
maybe 50 ohms or less.

Best,

Will


--- In ham_amplifiers@..., Tony King - W4ZT <w4zt-
060920@...> wrote:

R L Measures wrote:

On Oct 30, 2006, at 11:08 AM, zerobeat40 wrote:

Forget the link to the datasheet:



The only thing I have against the YC-156 is the noise...damn,

they're

loud, if you're wanting to run power and keep 'em cool.

One advantage of an 8171 is that a quiet 1700rpm blower will cool

one

VFB on SSB.

You can get a 1500 RPM blower from Dayton that will cool the YC-156/

179

and not be loud. They've got a nice two speed blower that'll do

even

better if you sense the cooling air temp and switch the speed ;)

73, Tony W4ZT

On Oct 30, 2006, at 6:38 PM, Tony King - W4ZT wrote:

The only thing I have against the YC-156 is the noise...damn,
they're
loud, if you're wanting to run power and keep 'em cool.

You can get a 1500 RPM blower from Dayton that will cool the
YC-156/179
and not be loud. They've got a nice two speed blower that'll do

even

better if you sense the cooling air temp and switch the speed ;)

I already had a monster blower on hand when I put my YC-156 amp
together. I drilled a hole in the wall, and ran the cooling air
thtough a 10 foot hose from another room. I hear no more noise than
the cooling fan on my PC makes here in the ham shack.

(((73)))
Phil, K5PC

On Oct 30, 2006, at 6:38 PM, Tony King - W4ZT wrote:

R L Measures wrote:

On Oct 30, 2006, at 11:08 AM, zerobeat40 wrote:

Forget the link to the datasheet:



The only thing I have against the YC-156 is the noise...damn, they're
loud, if you're wanting to run power and keep 'em cool.

One advantage of an 8171 is that a quiet 1700rpm blower will cool one
VFB on SSB.

You can get a 1500 RPM blower from Dayton that will cool the YC-156/179
and not be loud. They've got a nice two speed blower that'll do even
better if you sense the cooling air temp and switch the speed ;)

Two speeds are good, Tony, and proportional speed control with a DC- brushless motor is better yet Tektronix was doing this 30-yrs ago.

73, Tony W4ZT




Yahoo! Groups Links

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

On Oct 30, 2006, at 5:14 PM, pentalab wrote:

--- In ham_amplifiers@..., R L Measures <r@...> wrote:

### what have u got against HV fuses Rich?

RICH SEZ.... Do you carry two spare tires in your car? As I see

it, overkill is not good engineering - except perhaps on a moon
mission if I going.

### RL Drake used a .82 ohm 1 watt reistor in the B+ as a HV
fuse.... it always blows

RICH SEZ.... It is not a fuse at 2500v, it was a temporary metal

vapor arc that had a v-drop of c. 20v during the period when it
should have been limiting current.

#### Rich, obviously a .82 ohm resistor is not gonna limit
current. It's in there as a HV fuse.. that's it.... and easily
replaced...

You missed the point: A fuse that creates a metal vapour arc when it opens does not adequately limit peak-I until the arc is extinguished. This is why 250v 3AG fuses are bad engineering practice when used in a several kV application.

either with another .82 ohm-1 watt R... or a single
strand of real small ga wire.

Small wire also forms a metal vapour arc as it melts.

Either way... it opens BEFORE the
primary circuit breaker's open up. I have never had the breakers
on all 4 of my L4B's ever open in last 30 yrs.

...

RICH SEZ....The Henry 2k-4 has a resonant-choke filter --

perfect

for 120v operation with virtually no drop in PEP out.

### Trbl is... you would have to run a new heavy duty 20-

30 A 120 V line into the shack to run a Henry 2K-4.. on 120 V.

RICH SEZ... Not true. They run FB on SSB from a 120v, 15a circuit.

####### DREAM ON !! 120v x 15 A = 1800 va To calculate AC
mains VA.... take the DC input in watts and multiply x 1.22 [this
factor's in 10% for core losses.. and another 11% for power
factor]

The duty-cycle of 2-way SSB is under 20%. The old Plywood Box amplifier did 14 out on SSB and it did not trip the 40a, 240v breaker.

EG 1500w out/.63 = 2380 w input. 2380 x 1.22 =2904 va. 2904
Va/120 v = 24.2 AMPS !! Ur 120 v line is gonna SAG way b4 the
15 A breaker pops open.. with it's rinky dink 14 ga cu wire.

In
which case, you may as well run a 240V line in the 1st place...
unless u are talking about 600 w pep out on ssb.

RICH SEZ... no, 1500 pep. Resonant-choke filter DC supplies are

wonderful until you have to lift the sucker.

#### Resonant-choke filters, imo... are the most useless bloody
things ever devised.... and don't tell me 50 kw Broadcast
staion's use em.. they don't....

end

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

R L Measures wrote:

On Oct 30, 2006, at 11:08 AM, zerobeat40 wrote:

Forget the link to the datasheet:



The only thing I have against the YC-156 is the noise...damn, they're
loud, if you're wanting to run power and keep 'em cool.

One advantage of an 8171 is that a quiet 1700rpm blower will cool one VFB on SSB.

You can get a 1500 RPM blower from Dayton that will cool the YC-156/179 and not be loud. They've got a nice two speed blower that'll do even better if you sense the cooling air temp and switch the speed ;)

73, Tony W4ZT

On Oct 30, 2006, at 11:08 AM, zerobeat40 wrote:

Forget the link to the datasheet:



The only thing I have against the YC-156 is the noise...damn, they're
loud, if you're wanting to run power and keep 'em cool.

One advantage of an 8171 is that a quiet 1700rpm blower will cool one VFB on SSB.

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org

On Oct 30, 2006, at 1:57 PM, Peter Voelpel wrote:

________________________________

From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of pentalab

### These YC-156/YC-179's.. with their almost 19db of gain..

RICH SEZ..... Eimac says the gain is 14.2db at 6kV.

### Who cares what Eimac sez ?

...
### ...
I rather do my own measurements.
Other builders talk like fishermen,

Excellent chortles, Tnx, Peter

when I visit them I see and measure the
truth ;-)

73
Peter

...

R L Measures, AG6K, 805.386.3734
r@..., , rlm@..., www.somis.org