160 Meters

[WA1GFZ]

Last Night there was an AM QSO on 1.877, 1.880 and Astabula on 1885 P&Ming about slop buckets which were really AMers

[K9ACT]

I was working on my 160 tank coil last night and heard KYV calling CQ but really PW.  Nothing I could do would bring him up to his usual killer sig.

Nothing that is, until I switched from the dummy load to the 160 antenna.

By the time I got the coil back in he was gone for the night.

Wouldn't we all like a sig that can be heard on a dummy load 400 miles away.

js

p.s.  For Don... remember that conversation we had about plate current on the 810?

Don't know how this slipped by me but that rig is now only putting out about 175W at the rated 220 ma which at 1400v is 308w input or about 56% efficiency... not even good for a linear.  Guess I just kept increasing the plate current as the tube got tired.  Time to buy a new one and treat it better.  I used to get 250w at 220 ma.

You don't suppose it has anything to do with the fact that the tube was made in China...? Surely not.

jjs

[k4kyv]

My HF-300's are not a whole lot better.  I was disappointed at the best power measurement I  could make into the calibrated dummy load.  OTOH, according to my Hammy Hambone Mirage wattmeter, the Gates puts out more rf watts on 160 than I am running DC input to the final!  Maybe I have accidentally discovered the solution to the energy crisis - to hell with cold  fusion. 

If the manufacturer's tube data sheet indicates that a tube runs 70% efficiency at a given grid drive, plate voltage and plate current, which is the case of the 810, that is a theoretical, ideal, figure.  You have losses at every step of the process between the plate of the PA tube and the radiating antenna. 

A practical tank circuit, with circulating current losses in the coil, rf plate choke losses, and dielectric losses in the fixed and variable capacitors is likely doing extremely well to achieve 90% efficiency. The same could be said for the antenna tuner.  In fact, someone on another thread recently quoted the Handbook as saying that the link coupled balanced tuner typically runs only 80-85% efficiency. Then there is loss in the feedline.  I measured 7% loss on a 140' run of brand new RG-213 on 160m into a calibrated dummy load @ 1:1 SWR.  So assuming 90% efficiency at both the tank circuit and antenna tuner, plus 93% efficiency of the feedline, and 70% efficiency at the class C final, all give a grand total of 53%, which is probably still overly optimistic.  With a leen-yar running slopbucket it will be even less.

For the benefit of those  who are fixated on 375 watts of carrier output, running 750 watts DC input to the final comes very close to that figure.  700 watts DC input calculates to 371 watts, slightly under the figure. The popular urban legend that the present-day p.e.p. bullshit limits AM to 500 watts DC input to the final is just that - urban legend.

[K9ACT]

OTOH, according to my Hammy Hambone Mirage wattmeter, the Gates puts out more rf watts on 160 than I am running DC input to the final! 

I was getting the same results on 20 meters until I found that the Heath Monitor was screwing up the whole system.  Moving the pickup to the other side of the Bird normalized everything.  I spent weeks chasing spooks in the transmitter until I did this.  It acted like self oscillation and I could not use it on 20.

>If the manufacturer's tube data sheet indicates that a tube runs 70% efficiency at a given grid drive, plate voltage and plate current, which is the case of the 810, that is a theoretical, ideal, figure.  You have losses at every step of the process between the plate of the PA tube and the radiating antenna. 

Right but I am referring only to the RF power into a dummy load.

By contrast, my 8000's put out 425W RF with 600W DC input which is right at 70%.  This is running them at only 150 Ma per tube so maybe there is something to be said about being kind to big tubes.

>700 watts DC input calculates to 371 watts, slightly under the figure. The popular urban legend that the present-day p.e.p. bullshit limits AM to 500 watts DC input to the final is just that - urban legend.

It's the cost of replacing 8000's that keeps me at 600 w input.

js

[k4kyv]

It's the cost of replacing 8000's that keeps me at 600 w input.

The maximum CCS rating for a pair of 8000's or 810's in class-C plate modulated rf service is 640 watts DC input.  The maximum DC plate voltage is somewhere around 1600 volts.

ICAS ratings are up to a kilowatt per pair @ 2000 volts.  But ICAS ratings are basically controlled piss-beating of the tube.  RCA noted sometime just before or after WW2 that amateurs were still getting reasonable life out of a tube when running it beyond its rated limits, due to the intermittent nature of amateur transmission compared to broadcast service, so they made up another set of ratings for amateur use that was a compromise between tube life and transmitter power.  It still shortened the life of the tube to run them at ICAS ratings, but that was when tubes were plentiful, easy to find, but not necessarily cheap - try looking up the price of a larger transmitting tube in a pre-WW2 catalogue or magazine ad and then plug those prices into an inflation calculator.

[K9ACT]

I just learned something very interesting.  The tube didn't soften slowly.  In fact it didn't soften at all.

The power loss was sudden and related only to setting up camp on 160.

I reconfigured for both 40 and 80 meters and the original power levels are back.

With 300 watts input I get 225 out on 40 and 80 but only 175 on 160.  This is into a dummy load and not much different into the antennae.

What could be going on here?

js

[W2VW]

Wouldn't we all like a sig that can be heard on a dummy load 400 miles away.

My signal is heard by dummies over 400 miles away almost every time I get on 75.

[K9ACT]

Night after night I hear this real nice round table on 1885 and night after night a bunch of slop buckets camp out on 1888.  The only way I can hear the AM bunch is to listen to the lower sideband only but there still is interference from the buckets.  If anyone happens to be a bit high in freq they can not be heard at all.

It it pointless to discuss the mentality of the slop buckets but I can't help but wonder why the AMers insist on operating on 85 under these conditions.

Why not move down a few so we can enjoy what AM is supposed to be instead of hunkering down on the LSB and wearing hairshirts all night?

What is the magic to 1885?

The only thing that comes to mind is another group of AMer's that insist on setting up camp on 1880.  This puts the 1885 group between a rock and a hard place.

Not sure where this can go but I have been having more fun with RTTY on 1808 the last few nights than tangling with slop buckets up the band.

Jack

[K5UJ]

What could be going on here?

From my experience only thing I can offer is ur output tank circuit needs help on 160?  More coil; more load cap?

About the buckets on 1888 I don't know Jack, maybe you are the only one bothered by them?  last couple times I was on there I worked HLR and KYV and they both strapped anyone nearby.  I'm planning on eventually getting one of those Sherwood sync detectors to go with my 75A3 but I thought that you could notch anything out with that high tech SDR receiver of yours.  I've seen a friend's SDR and he always likes to show me how he can click his mouse and move the passband around independently of carrier.   I'd try cutting out the uppersideband on 1885 and just get the carrier and lower sideband.

73

Rob
K5UJ

[wa2dtw]

The slopbuckets on 1888 have made 1885 almost unusable, unless we have the big time strappers on frequency.   And the AM activity on 1880 makes it impossible to move down.  (and 5 kc is too close for two good AM QSO's anyway).  Lately, it is very difficult to find a sweet spot on 160 meters.

[K9ACT]

About the buckets on 1888 I don't know Jack, maybe you are the only one bothered by them?  last couple times I was on there I worked HLR and KYV and they both strapped anyone nearby. 

That is a special case.  What about a round table including not so strong stations?   Unlike 75 meters, there are not many strapping East Coast sigs on 160

>I'd try cutting out the uppersideband on 1885 and just get the carrier and lower sideband.

That is a given which I already discussed.  If the 85 gang moved to 83 and the 80 gang moved to 75 we could all enjoy AM as it should be. 

js

[W3GMS]

Yes those SSB ops on 1.888 are creating problems.  The other night an AM station switched to SSB and broke in on the group on 88 and got them to move up to 90.  That made things much better.  The comment was made that the ops on 88 are very close to each other and are not bothered by the AM operation on 85.  It may be worth talking to the group "nicely" on 88 and asking them to move up.  It worked the other night so it may work again. 
Joe, W3GMS

[Bill, KD0HG]

Sheesh.
Where's all the guys with the ex-broadcast iron?

[W3GMS]

Bill,
That does not do it in this case!  They are real close to each other and I think they could hear each other with a paper clip as an antenna!  I have the broadcast stuff here but nothing phases them except asking them to QSY.   
Joe

[K9ACT]

Yes those SSB ops on 1.888 are creating problems.  The other night an AM station switched to SSB and broke in on the group on 88 and got them to move up to 90.  That made things much better. 

That's a great idea.  I guess the main reason I didn't think of it is because I have no SSB conveniently available.

If they can't or don't want to move just pushing the USB button would make most of the problem go away.

js

[K5UJ]

Of course if they are there on 1888 carrying on first then sure, a move to 1880 or something is in order so as to not start any problems however if I am having a nice chat with someone on 1885 and after a few minutes these folks start up then they are lids and I don't see why I should be shoved out of the way.   It occurs to me that if they are all near each other then they can be nulled out with a small rotatable rx loop.  A separate rx antenna on 160 is a good idea anyway.   

I agree that politely asking them to QSY if they showed up _after_ the AM qso got started is a good idea.  the QRM may be due to radio ignorance on their part.  There are hams operating SSB who have no understanding of bandwidth and the meaning of the frequency display vis a vis their signal.   check out the upper band edge of 20 m. sometime or the lower edge of the U.S. 40 m. phone band and you will hear SSB stations going over the edges.

[Pete, WA2CWA]

Has the 160 band shrunk over the last several days. You're all diddling between 1880, 1885, 1888, etc. AM works above 1900 and even below 1880. I've worked AM stations on 1910, 1945, and even up around 1980. You all seem to be trying to turn 160 AM operation into one of those imaginary windows with the typical P&M.

[Ed/KB1HYS]

All I want for Christmas is a V F O...

Sri, sometimes I be a wiz-a$$...

[wd8das]

Pete wrote:

>I've worked AM stations on 1910, 1945, and even up around 1980.

Certainly - I spend most of my 160m operation on 1985 kHz.  Glorious fun!  Come on up to 160...

Steve WD8DAS

[k4kyv]

We had a nice group on 1885 AM to-night.  About 5 of us, all using retired broadcast rigs, and most of the content of the discussion was various modifications and solutions to problems encountered getting the xmtrs to work on 160. Strapping signals, good quality, no slopbucket QRM.

[K9ACT]

We had a nice group on 1885 AM to-night.

When W9GT called CQ, I doubled with you in responding and you won.

It was getting on to cocktail time so I just listened for awhile.

Came back after dinner and the band was totally vacated except for the buckets on 1888.  I listened a bit and looked up a call sign, W9 something  but he is in Texas.

Bits and pieces of the conversation include some one saying he was accused  of "being really wide" last night and they all agreed.  He backed off to 500W and they did some reasonable analysis of his problem.  Seem like reasonable people that just  picked a bad place to hold court on LSB.

Later on, my noise level went up to almost S9 from the usual S3.  I called CQ for a while and worked W9ABC about 20 miles away and had to wear earphones to copy his 20 over sig.

Strange night.

Jack






 Strapping signals, good quality, no slopbucket QRM.