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eHam Forums => Misc => Topic started by: 2E0BSS on August 21, 2007, 02:36:38 PM



Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: 2E0BSS on August 21, 2007, 02:36:38 PM
I have an interesting question (for me it's interesting) I am licensed as a 2E (intermediate) here in the uk which gives me, on most bands, 50 watts PEP I don't have a stand alone watt meter just one on the SWR meter of my MFJ 948 Versa tuner, however, I'm unsure how to calculate the PEP power when tuning my FT 101 E up. This is how I set power up please correct me if I'm incorrect.

First tune the radio to all the dips and max powers then switch the 948 to PEAK on the meter and lower the power untill it sits just below the 50 watt point in both tuned and bypass just to make sure. The MFJ instruction manual states to the following:

"Peak Power and Average power values are equal with steady unmodulated carriers ie FSK, FM. The PEP is twice the average power with SSB two tone test modulation and may be any amount larger than the average power SSB voice signals"

What does that actually mean as the FT 101 E cannot do FM just AM/CW/SSB.

Any help will be greatly appreciated so I can run the correct power from my FT 101E

Charlotte 2E0BSS


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on August 21, 2007, 03:03:30 PM
That's a challenge since the FT101E has absolutely NO power output adjustment of any kind when used on SSB!


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: 2E0BSS on August 21, 2007, 03:29:51 PM
Ok that's very interesting so when I adjust the  carrier to lower the power what am I actually lowering ? The power on SWR meter does drop and the reports I get are no different to my 857D on 50 Watts.

I previously was told if I lower the Carrier till the 50 watts or as near as possible to it is lined up with the needle then I'm transmitting around that power I guess that's incorrect info. How can people operate on Top band with them at a lower power level ie over here in the uk it's 32 Watts

Any more advise would be greatly appreciate. Does anyone know where I can get the unit serviced ? mainly in the UK

Thanks Charlotte 2E0BSS


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: KE3WD on August 21, 2007, 05:57:16 PM
I think what you are doing will "put you in the ballpark".  And after all, it is all that you can do with that meter.  

I also don't think that they expect you to nail the 50WPEP with a calibrated instrument, either!

You could also measure DC Voltage and Amperage at the power supply and multiply by efficiency factor, or even get into that ballpark with the AC mains voltage/current, but again, I think that you are giving it the old college try here.  

But I don't know what the situation is in your country, if you actually have inspectors or the like who will knock on doors demanding to use their equipment to measure your power output, that would be another story entirely.  

Outside, they aren't going to be able to tell all that accurately whether your signal is 40, 50 or 75W PEP at the radio antenna jack.  


KE3WD


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: KE3WD on August 21, 2007, 06:01:27 PM
>> previously was told if I lower the Carrier till the 50 watts or as near as possible to it is lined up with the needle then I'm transmitting around that power I guess that's incorrect info. How can people operate on Top band with them at a lower power level ie over here in the uk it's 32 Watts <<

If you can't adjust the rig down low enough from the front panel, the thing will have to be modified internally to accomplish this.  

Not all that hard to do, lowering output power is a lot easier than trying to make it higher than the radio is designed to do and will also derate the PA quite a bit, the tubes should last virtually forever.  

Cutting the power in half is likely as easy as inserting a plate voltage dropping resistor in the right place.  There are other ways, of course.  This one is "brute force".  


KE3WD


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: KE3WD on August 21, 2007, 06:16:20 PM
BTW the Manual for the 101E states, "The operator may select any power output desired by simply rotating the "CARRIER" control within the limits of its range from one to ten".  

Are you saying that with the CAR control all the way CCW, the output power is still too high to meet your requirements?



Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: W2RDD on August 22, 2007, 03:26:51 AM
Congratulations on having your intermediate license and for making every effort to be an "honest" operator. Ethical behavior is rare these days.


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: N8UZE on August 22, 2007, 05:31:11 AM
Use CW mode to tune and check your PEP.  The average and peak are identical on this mode and it is a mode that your radio has.  If the PEP on CW is 50watts, your SSB PEP will not exceed 50 watts either.


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: 2E0BSS on August 22, 2007, 09:59:29 AM
today my mic quit on me for my 101E so I'm guessing the problems may have related to it. As for the power issues I've checked the meter against known accuracy set up my 101E accordingly so it's going to be around 50watts.

Now go to find a replacement mic for my 101E. Thinking of the new MFJ one for Yaesu, although it's so new no store can tell me if they work as they haven't sold any.

Yaesu are sending me all the manuals for the radio including the technical supplement so that will be a start.

Charlotte 2E0BSS


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on August 22, 2007, 02:39:07 PM
The one mistake in what you're doing is that the CARRIER control has no effect whatever on SSB power.

It adjusts the output in the CW mode from "full" to very low (nearly zero) if you turn it all the way down.

However, go ahead and do that: Turn it ALL THE WAY DOWN, to "zero," and then use SSB.  Your output power will be the same as it was when it was all the way up.

The carrier control does not adjust SSB output power, only CW.

Same goes for the TS-520S and virtually all transceivers from the 1960s through the 1970s, and even a bit into the 1980s.  

WB2WIK/6


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: 2E0BSS on August 22, 2007, 03:54:17 PM
So no matter what my ATU is saying the Radio is still transmitting at around 130 Watts PEP? This is bad news. Is there any way at all including turning the VR's inside to lower the physical power output. I'm still at a loss though because over here in the UK Top Band (160m) has a max of 32Watts how do hams comply with that? I know of hams who use FT 101 series units.


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on August 23, 2007, 10:14:12 AM
There are ways to reduce FT-101 power, but turning down the CARRIER control isn't one of them, unless you're on CW.

Of course, MOST DXing on 160m *is* CW, so maybe that explains what they're doing on 160.

To reduce SSB output power, you can use a variable voltage power supply applied to the ALC input contact on the FT-101 rear panel.  This would be a "negative" voltage power supply (+ from the supply would be chassis ground), so it must be isolated.  I've used something as simple as a 9V alkaline battery with a 10K potentiometer wired across it, using the wiper terminal and one end terminal to produce an adjustable external negative ALC voltage from 0 to 9V.  That's usually about sufficient to turn the transmitter power down quite low.

I would NOT recommend making any internal adjustments in the FT-101.

WB2WIK/6



Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: KE3WD on August 23, 2007, 07:26:41 PM
WB2WIK -- Using a pot as voltage divider into the ALC (and the 9V battery) is a great idea!  

shoulda thunk of it.  


KE3WD


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: N1UK on August 25, 2007, 02:02:56 PM
Can't he just reduce the mike gain? It certainly reduces the power very nicely on my TS930S.

The peak power meter on the MFJ is likely to read low. To get an accurate PEP measurement you need a meter with active circuitry in it. This is a nice one

 
http://www.eham.net/reviews/detail/5691
 
http://www.daiwa-industry.co.jp/radio/ham_e/cn801ehp.htm
 


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on August 25, 2007, 10:02:11 PM
Don't confuse "PEP" and "peak", people.  Peak power meters are the ones that need the active circuitry and therefore need a power supply (wall wart or internal battery) to run this circuitry.  Many relatively inexpensive meters read average and PEP, but not true peak.  My MFJ-986 tuner says "peak", but it really isn't; it's PEP.


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: N1UK on August 26, 2007, 07:22:27 AM
Yes I was confusing the two . Thank you for putting me straight on that one. How accurate is the MFJ at reading PEP?

Mark N1UK G3ZZM


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on August 28, 2007, 10:11:38 AM
It agrees pretty closely with PEP meters from other manufacturers.  Probably within plus/minus five to ten percent of the "true" reading.  


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on August 28, 2007, 01:18:24 PM
Don't confuse PEP and peak?  What are you talking about?

To measure PEP power, of course active, powered circuitry is absolutely required.  What would bias the peak sample and hold circuit?  It can't be powered by RF or by magic.

There's no definition or usage of "peak" power in the world of voice modulated radio transmitters, at all.  PEP is the only term used and defined.  The ITU regulates this worldwide, and they only define power three ways: None of those are "peak."

A pretty good writeup on this is here:

http://www.vk1od.net/VSWR/MeasureSSBTxPower.htm

WB2WIK/6


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on September 04, 2007, 05:23:16 PM
Steve - I think the folks at Bird know what they're talking about.  Their Model 43, as I know you know, measures CW power (which is the same thing as PEP, for all practical purposes - or so I have been trained to believe).  It has NO internal batteries or external power supply of any sort, for any purpose.

The Model 43P DOES require batteries or external power for operating the Peak (not PEP) reading circuitry.

Whether such instrumentation as Peak RF Wattmeters is necessary (and maybe it's not, judging from your last post) is not for me to determine.  However, if as respected an authority in the field as Bird chooses to design, manufacture and sell such instrumentation, I'd imagine they have a good reason.

I used to work in a Navy calibration lab, and one of the types of instruments I'd receive for calibration and/or repair were Birds and their associated slugs.  At that time, each Bird 43 HAD to be calibrated with slugs identifiable by serial number, and woe to the technician on the waterfront who used a slug that wasn't on the list for a particular Bird 43!


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on September 05, 2007, 10:43:05 AM
>RE: FT 101 E Peak Envelope Power MFJ 948 Tuner  Reply  
by K7KBN on September 4, 2007  Mail this to a friend!  
Steve - I think the folks at Bird know what they're talking about.<

::Yes, they do.  I wrote some of their marketing collateral for them back in 1969.

>Their Model 43, as I know you know, measures CW power (which is the same thing as PEP, for all practical purposes - or so I have been trained to believe).<

::Nope, your training is very wrong.  CW and PEP are the same power when using CW, which is a continuous wave mode, providing the CW signal isn't interrupted by keying to add communications intelligence.  FM and PEP would also be the same, and for the same reason; no amplitude modulation.  As soon as you go to any AM mode including SSB, there are huge differences in measurement requirements and a Bird 43 cannot measure PEP at all, unless the operating mode is CW or FM where there is no amplitude modulation.  Bird 43 cannot measure PEP for AM, for SSB, for pulse modulation...

>It has NO internal batteries or external power supply of any sort, for any purpose.<

::That's true, it doesn't need any since a CW signal is continuous wave.  A keyed CW signal (A1A) is an interrupted continuous wave.  If you send dits and dahs when using a Bird 43 to measure power, you'll see it indicates *WAY* less power than if you just close the key continuously and send a carrier.  That's because it can't measure PEP.  If you use a Bird 43P (the PEP version of the same meter), you'll see the continuous carrier or the dits-and-dahs sending will both read the same power.

>The Model 43P DOES require batteries or external power for operating the Peak (not PEP) reading circuitry.<

::The 43P is a "PEP" reading meter, by definition.  Again, no matter what anyone calls it, there are only a few ways to indicate power according to the I.T.U., which regulates all transmitters everywhere in the world including here.  PEP is one of them.  "Peak" is not one of them.

>Whether such instrumentation as Peak RF Wattmeters is necessary (and maybe it's not, judging from your last post) is not for me to determine. However, if as respected an authority in the field as Bird chooses to design, manufacture and sell such instrumentation, I'd imagine they have a good reason.<

::Well, sure they do.  A Bird 43 and many other instruments are very useful for measuring the output power of FM transmitters, for example: No amplitude modulaton means an FM signal is the same as an uninterrupted CW signal.  It's CW power.  Bird 43s can also be used to measure the carrier output power of an AM transmitter, as long as you're only interested in measuring carrier power.  It can't measure the PEP power of an AM transmitter, which is the only thing amateur radio operators should be concerned with, since we are regulated by PEP power and not carrier power in Part 97.

-WB2WIK/6


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on September 05, 2007, 03:44:01 PM
Okay.  Just to point out, however, that the Bird 43/43P operating manual - at least the one online - makes no mention whatsoever of "PEP", and refers to the 43P as a "PEAK" reading instrument.  Perhaps you should correct them.


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on September 07, 2007, 11:14:05 AM
KBN: What you say doesn't seem to be true (far as I can tell).

The model 43P was discontinued and replaced with this one, which does have its data sheet and manual on line and they do refer to it as a "PEP" wattmeter as follows (cut and pasted from Bird Electronic website five minutes ago):

>4314B Thruline® Wattmeter
 PEP, Single element, Portable Wattmeter
 Accurate CW and Peak Envelope (PEP) field power measurement over 450 kHz to 2.7 GHz and 100 mW to 10 KW.
Uses industry standard Bird elements with space to store 2 additional within the meter housing.
Rugged metal housing for the most demanding environments.
Quick Change (QC) connectors to minimize the need for adaptors when making critical measurements.
 
 
 The Bird 4314B Wattmeter is similar to the Bird Model 43 Thruline Wattmeter but also contains electronic circuitry to accurately measure peak envelope power which is present in amplitude modulated signals such as AM broadcast, single sideband and TV video transmitters. The circuitry operates from 2 standard 9V alkaline batteries or an optional A.C. adaptor.<

They have no listing whatever for the 43P that I could find.  And this one, the 4314B, appears identical to the 43P's that I own, I don't see any difference except the model number.

And they DO call it a "PEP" meter.  

WB2WIK/6
 


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: 2E0BSS on September 07, 2007, 11:31:00 AM
Great information folks. I'm in the process of having the unit serviced by an expert (someone who knows these things and fixes them professionally) upto now the set isn't doing to well it's off transmitting frequency by 6.75kc's and it's receive frequency isn't much better either ok that's only out by a variable 3-6 depends on the frequency used.

As for RF power well that's not too good either it will push 90watts this drops off after a few seconds and if continually used it goes to around 10 watts.

I'm having the set serviced because it's what I consider amatuer radio (seeing a set like that some 30 years ago gave me the radio bug)I'm not a fan of all these new base stations which glow all pretty colours plus the FT101E's sound is better than the lot oh that was one thing the engineers first report said was ok the receiver is working all be it off frequency.


I'm now looking for the service equipment myself so I can get a dead radio and try to fix it any advise on finding the individual units would be great.


Charlotte 2E0BSS



Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on September 08, 2007, 08:09:39 AM
http://www.repeater-builder.com/other-mfrs/bird-43-wattmeter-2001.pdf


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: WB2WIK on September 09, 2007, 11:59:00 AM
K7KBN, that's a six year-old reference on a "ham" independent web site; it's not Bird's website, and if you look at Bird's website you'll see the 43P is indeed discontinued and replaced by the 4310 which is listed as a "PEP" wattmeter.

Bird discovered their mistake (using the term "peak" instead of PEP, since there is no definition of peak power in international regulations) and changed it in 2004.

WB2WIK/6


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on September 09, 2007, 02:27:45 PM
Thanks, Steve.


Title: FT 101 E Peak Envelope Power MFJ 948 Tuner
Post by: K7KBN on September 09, 2007, 02:28:04 PM
Thanks, Steve.