Phil W9IXX has a New email address
Hi,
FYI new email below:
73, Phil W9IXX
|
Re: Amplifier failure to key
The last page of the "Advanced Users' Manual" for the ARB-704
says this about Technical Assistance:
"If you have any problem with this unit first check the
appropriate section of this manual. If the manual does not
reference your problem or reading the manual does not solve your
problem, call Ameritron at 662-323-8211. We can
only help if you have your ARB-704 manual, radio manual, and
information about your station available during the call.
We strongly recommend calling Ameritron with any questions,
but questions can be mailed directly to Ameritron at 116 Willow
Road, Starkville, MS 39759 or Faxed to 662-323-9810. Please be
aware that MFJ is a separate facility, and as such does not always
offer the best assistance with Ameritron products. Be sure to send
a complete description of the problem, explain how this unit is
being used, and include a complete description of your station."
I have several ARB-704s of my own, and since one was at hand and
I had the necessary jumper cables and ohmmeter at hand, decided to
see whether one can determine whether the ARB-704 is, indeed,
working with just an ohmmeter. My meter is the moderately-priced
Harbor Fright Centech-brand model 61593; your results might differ
from mine depending upon your meter.
First, hook up the -704; plug in power, plug in a RCA cable to
the Radio jack, then check that when you short the center RCA pin,
the front panel Transmit follows your shorting of the
center pin. Next, plug your ohmmeter into the jack on the rear
panel labeled Amp. If your meter is like mine, I plugged
my Red ohmmeter lead into the center pin of the Amp RCA
socket and connected the black lead to the shell of the jack.
Next, I set the meter to the "Diode Check-Buzzer" position
on the Ohms range scale, which, on my meter, is just CCW of the
Ohms ranges (it shows a tiny diode symbol to indicate you can
check diodes on that switch position). Now, shorting the Radio
jack's RCA center pin to ground causes the front panel LED on the
'704 to light up, and also causes my ohmmeter to read around 0.63.
Switching the ohmmeter to any other resistance range, I have to
set it to a high resistance scale such as 200K or higher before it
will read again. With the RCA center pin unshorted, the meter
reads infinite resistance; shorting the pin makes the meter read
some arbitrary resistance (we don't really care what resistance,
since we're just trying to find out whether we can even test the
ARB-704 with just an ohmmeter).
Now, if you plug your amplifier into the Amp socket on the '704,
you should be able to switch it into Transmit as you manually
short the center pin of the Radio socket on the -704. If so, move
the Radio socket cable back to your FT-3000 and see whether it now
works; it should. BUUUUTTTT....
The ARB-704 manual does mention this, on page 8 of the manual: "QSK
Radios Some QSK transceivers (mostly early Yaesu's) have a
control terminal or jack labeled "Inhibit" or "Linear that has to
be grounded on transmit. Consult the radio manual for details on
this particular requirement. This connection prevents hot
switching of an external power amplifier, and is normally wired to
a "handshake" line on a QSK amplifier that tells the radio the
amplifier has successfully gone into the transmit mode." It is
possible that while you were moving things around, you somehow
moved this setting on your radio and it's no longer working the
same way.
73,
Steve KJ0XP
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Re: Amplifier failure to key
You narrowed?it down. Good job. Maybe MFJ can give you some troubleshooting tips for the ARB-704. Please let us know what you find out. Bob? W4JFA
Hal
Thanks for the input and suggestion.? I was trying to figure out a safe way to do some troubleshooting.? I say safe because I am a mechanical guy so I don't always understand the test results I get and I worry about taking my failed electronic item and turning it into a worthless electronic item because of shorting something out, etc.? Electrical/electronic is my weaker suit.? It is much easier with mechanics, you see the leak, etc.? HiHi.
Anyway, I did use a DMM and read out the Amp 15 pin connector on the back of the 3000.? I was pleased to see it appeared okay and the 3000 out was as expected.? Then I looked for continuity on the five conductors of the Plug & Play cable.? There was continuity on all five between five pins on the 15 pin and the 5 pin on the other end.? However, I was surprised to see the match up of the two ends.? I would have expected a different match-up, unless I am reading/viewing this incorrectly.
Finally, I took the RCA relay cable I had between the ARB-704 and the amp relay jack and went from the FTdx 3000 "Tx Gnd" jack and the amp Relay jack.? The amp keyed on transmit.? Based on this I am leaning to something wrong in the interface (ARB-704).? It does have several transistors and diodes.? I thought I would try and test them,
Again, thanks for the dialog and advice.? Attached is a synopsis of my testing to date.? Take care.
73 Harrison N1FAM
?? ?
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Re: Amprepairguy Is Now The new Owner Of Harbach Electronics !!!!!!
Jim, I'm assuming he'll still?have all of the power supply circuit boards/kits? Bob? W4JFA
It's still in a transitional phase as of today.? A lot of items are being shipped from OH to CT.
A lot of new items will be added, including the entire Penta tube lineup, for both amateur and commercial users.
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Re: Amplifier failure to key
Hal
Thanks for the input and suggestion.? I was trying to figure out a safe way to do some troubleshooting.? I say safe because I am a mechanical guy so I don't always understand the test results I get and I worry about taking my failed electronic item and turning it into a worthless electronic item because of shorting something out, etc.? Electrical/electronic is my weaker suit.? It is much easier with mechanics, you see the leak, etc.? HiHi.
Anyway, I did use a DMM and read out the Amp 15 pin connector on the back of the 3000.? I was pleased to see it appeared okay and the 3000 out was as expected.? Then I looked for continuity on the five conductors of the Plug & Play cable.? There was continuity on all five between five pins on the 15 pin and the 5 pin on the other end.? However, I was surprised to see the match up of the two ends.? I would have expected a different match-up, unless I am reading/viewing this incorrectly.
Finally, I took the RCA relay cable I had between the ARB-704 and the amp relay jack and went from the FTdx 3000 "Tx Gnd" jack and the amp Relay jack.? The amp keyed on transmit.? Based on this I am leaning to something wrong in the interface (ARB-704).? It does have several transistors and diodes.? I thought I would try and test them,
Again, thanks for the dialog and advice.? Attached is a synopsis of my testing to date.? Take care.
73 Harrison N1FAM
?? ?
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Re: Amplifier failure to key
Dear Harrison,
?
Perhaps using a DMM you might wish to verify the
Amplifier Keying Jack on the ¡®3000 is closing when
you PTT.
?
Perhaps you might rig up a dummy jumper with
a switch to actually operate the keying on the
amplifiers.
?
That will help pinpoint.
?
Hal
W4HBM
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Amprepairguy Is Now The new Owner Of Harbach Electronics !!!!!!
It's still in a transitional phase as of today.? A lot of items are being shipped from OH to CT.
A lot of new items will be added, including the entire Penta tube lineup, for both amateur and commercial users.
|
I have an Ameritron 811H and a Dentron Clipperton L amplifier that I was driving with a Yaesu FTdx3000 through the Ameritron ARB-704 interface (only one in the circuit at a time) .? I am using the plug and play cable between the 3000 and either amp.? Now neither amp seems to key. With the amp in standby all seems well and I am able to communicate as normal.
It would appear that the relay on either amp does not closes.? I.E., when I PTT on the transmitter I get the 3000 transmit LED as well as the LED on the 704 but nothing on either amp.
I was planning to try to read out the voltages coming out of the linear out connection on the 3000 for a starter.? Being both amps are acting the same I am thinking that the problem is with the 3000.? Lastly, I will not totally rule out operator error.? Any and all advice On what I should check or how I should proceed is appreciated.? Attached is a pictorial of my set up.
Post note:? don¡¯t know if this is relevant but rereading the 704 manual it states that 13.8 volts is coming from the transceiver through the plug and play cable.? As a result no external power to the ARB-704 is necessary.? In addition to the plug and play cable I have had a 12V wall wart feeding the ARB-704.? Fortunately, I didn¡¯t see any ill effects before this point.
Thank you.? 73 Harrison N1FAM
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12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 16
- 12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 16
Here all the various tank coil taps are completed. Adjustable SS spark gap installed across the vac load cap. After this video was done, the 2nd adjustable SS spark gap was installed across the vac tune cap. Spark gap across the load cap protects the load cap. Spark gap across the vac tune cap protects the vac tune cap AND the bandswitch.
There is also a.... '.7 uh pre-coil'...... that is wired between output of plate block cap assy....and the hot side of the C1 vac tune cap. The anode to grid C + stray C (lower anode fins to chassis) and this .7 uh pre-coil form the step down L network. This transforms the 1600 ohm plate load Z (7200 vdc loaded @ 2.5 amps) down to just 361 ohms @ 21.225 mhz. Then a lower, loaded tank Q can be used for the PI network on 15m. That L network also has a lesser effect on all lower bands. IE: 939 ohms @ 14.175 mhz. 1419 ohms @ 7.150 mhz etc, etc.
The original target value for the pre-coil was .6 uh. (which would have transformed the plate load Z down to just 483 ohms @ 21.225 mhz). Trying to tap a tubing coil is tough enough as it gets.
With the temp 1600 ohm resistor from anode to chassis....and analyzer on output side (and the pair of RJ2B's relays externally powered on), the swr was 1:1 after tweaking the tune + load to the calculated values for each band = jives with the spreadsheet / GM3SEK software. Previously, both the vac tune + load caps were mapped out, with pf vs turns counters....and a cheat sheet made up.
On a similar note, once the tune + load caps tweaked for 1:1 swr, the caps are left alone....and the upper / lower freqs for the 2:1 swr points are noted down. 160 khz wide on 160m, 310 khz on 80m, 600 khz on 40m, 800 khz on 20m, and 1 mhz on 15m.
So far, so good. All measurements for the adjustment of the tune + load caps were done with the top lid on.
All playlists.?
?
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12 KW CCS ON 160-15M...USING THE 3CX-6000A7... PART 15
Here the plate block cap assy is installed.?
5 x 200pf @ 15 kv rated doorknob caps are used to make up the assy. The 200 pf cap's were chosen since they are rated at 15 amps CCS of RF current on any freq > 5.11 mhz.? Total max current rating is now 75 amps.? Total capacitance is 1000 pf.? (The 200 pf HT-57 cap is the....'go to'.... cap for the HT-57 series since their 200 pf cap has the highest current rating of the entire HT-57 series).? Similarly for the bigger HT-59 series, the ...'go to cap'.....in a HT-59 is their 250 pf cap, rated at 35.5 amps? CCS on any freq > 16.0 mhz).
1000 pf = 88 ohms of XC? @ 1.8 mhz? ? ?The general rule for plate block cap total value is.... The XC of the plate block cap assy shouldn't be any more than 5% of the plate load Z...at the lowest freq used (1.8 mhz in this case).? In this case, with 7 kv loaded B+ @ 2.5 amps, the plate load Z = 1555 ohms.? 5% of 1555 ohms = 78 ohms.? 1200 pf would have been 73 ohms of XC.... but in this case, there is severe space restraints, and only 5 x caps can be used.? Close enough for this application.
2 x copper straps used, one above, and one below..... with the input at the tube end on top.... and the output at the opposite end...on the bottom.? ?Done this way so the total physical, combined distance in + out, stays the same for each cap.? Done this way, the RF current is equally divided between the 5 x caps.? ?(Another similar method used, when 6 or 8 caps are used, is 2 rows of 3 caps.... or 2 rows of 4 x caps. In those cases, the input is dead center between 2 x caps at left side of the top plate...and output is dead center between? last 2 x caps, at right side of bottom plate.? Same deal, the current will divide equally between the caps).
HEC (high energy Corp) sez the PEAK RF voltage ACROSS the cap (or paralleled cap assy).....PLUS any ...'DC bias' can not exceed the stamped cap's voltage? rating.? ?What HEC calls ...'DC bias', we call B+.? ? ?The saving grace at the low freq end (160m) is.... there is hardly any RF current flowing through the plate block cap asy.....and the peak RF voltage is very little.
At the upper end of the HF spectrum, 10m, there is a LOT of RF current flowing through the block cap assy. Reason is..... the anode to grid C on the tube makes up 90% of the total required C1 tune C.? Think of it as the tube C is 90% of the required C....and the actual C1 tune cap is a tiny, variable padder.? ?Issue is.... the plate block cap resides between the anode and the C1 tune cap.? All that current that flows through the tube C now also has to pass through the block cap assy.
The XC of a 1000 pf cap on 29 mhz = 5.5 ohms.? So even with high current flowing through the block cap, the peak RF voltage is still miniscule.
Just to recap, enough C is required for the lowest freq....and the cap has to be able to handle a lot of current on upper HF.
|
I'm not sure if my answer came through so... I hooked up the amp through a power meter then dummy load. Amp is fine.
Thanks for the info guys.
Bob W4JFA?
On Thu, Mar 28, 2024, 12:15 PM W7WRX < clark@...> wrote:
On the 374A, 10 meters is just the Load cap. Its fixed tune.? So if you set the load cap to like 70 on the dial, You get instant 10, 15,20,40 and 80 with no tuning.??
I/we noticed the same thing on my 2x 3-1000Z amp.? Not sure if you remember.? I kept "walking" the coil and each time got more power. Eventually, increase stopped.? This makes a huge difference on higher bands.??
I also noticed this phenomenon can occur with the combo of Tune and load cap.? ?I like to "walk" the load cap in fixed degrees and peak the tune. There is a perfect spot. It will fall off on either side.
I am unsure why this happens.? It does happen on Most henry amps and the alphas. This does NOT occur on the SB220 for example. The load has one peak and its broad and soft.
The 2k4A was really bad about this. If you just dialed up the tune and load for peak or carrier. You would be sure to be way OFF.? Stepping the load control and adjusting tune again and you can find that sweet spot.
C
Interestingly enough, after looking at the schematics for the 450/500/550 NT series of amplifiers,? they all use a PI network? on 160-10m.? ?BUT they use a lower, loaded Q.? ( more coil, less tune + load C).?
The alpha 78/ 374A etc, in broadband mode, ( and? also manual tune),? all use a PI-L..... same deal though, a lower loaded Q is used, when switching from 'manual tune'? to ....'broadband'.? ?In broadband mode, more L is used on 80-40-20-15m.?
The broadband feature on the alpha amps only works on 80-15m.? Strictly manual tune on 160+10m.?
?
I asked glen, AE0Q, the alpha fellow, why they didn't use the same deal on their newer amps (9500 / 8410).? He said the 78/374A? etc, had lower eff vs manual tuning.? So they switched to motor driven tune + load caps..and the bandswitch.?
?
Funny thing is, on one of my older 4-1000 amps, with the roller coil in it? ( and also my 3x3 with a roller).... when normal? Q used ( this is a PI), like 12-15, PO was good.? But then tried increasing the uh on the roller a bit ( and slightly less on the
tune + load caps)..and PO increased.? ?So repeated the process again, with more uh, less tune and load C..and again, PO increased.? Repeated several more times, in small increments, ( each time retuning the amp with the same drive level)...and PO kept on increasing,
Then no more PO with any further increases in uh.? ?It just flat lined with max PO, regardless of how much uh was dialed in.?
So I backed down the uh, until PO just started to drop off a few watts.... and left it there. This was all on 75m.? ?Same deal on the other bands.? ?The idea here is to use a lower Q...but just low enough to do the job.? ?Go too low, and PO stays the same,
(no more increase) even more broad banded, but I highly suspect the harmonic suppression is severely de-graded.?
?
There is NO spec for harmonic suppression in the online manual for the 450/500/550? (which also covers the NT versions).? ?
?
It would be interesting to know what the actual harmonic suppression is on each band on the NT versions.?
|
Re: Various uses for metal tube RF amplifiers
I am sure every hospital has Scott's phone number on speed dial?? Wink Wink
On Saturday, March 30, 2024 at 10:52:44 AM EDT, Jim VE7RF <jim.thom@...> wrote:
Any of these bigger metal tube amplifiers can be used for:
(A) ISM
(B) educational
(C) testing DL's.
(D) CAP
(E) MARS
(F) plasma
(G) sputtering
(H) tube testing
(I) deep tissue healing
(J) diathermy
(k) low latency, high speed stock market transactions
(L) SW broadcast
(M) marine
 Superbowl 6 (O) Embassy
(P) CQ WW
(Q) Etching
(R) emergency use
(S) military
(T) irradiation.
Ok, here's the deal.
Next time some bozo asks.....'where is this amp legal'....and 'why so much power' they can look at the above list....and pick one or more at random.
|
Various uses for metal tube RF amplifiers
Any of these bigger metal tube amplifiers can be used for:
(A) ISM
(B) educational
(C) testing DL's.
(D) CAP
(E) MARS
(F) plasma
(G) sputtering
(H) tube testing
(I) deep tissue healing
(J) diathermy
(k) low latency, high speed stock market transactions
(L) SW broadcast
(M) marine
Superbowl 6 (O) Embassy
(P) CQ WW
(Q) Etching
(R) emergency use
(S) military
(T) irradiation.
Ok, here's the deal.
Next time some bozo asks.....'where is this amp legal'....and 'why so much power' they can look at the above list....and pick one or more at random.
|
12 KW CCS ON 160-15M...USING THE 3CX-6000A7... PART 14
HERE THE FRONT PANEL IS DONE..AND PAINTED. THE 2 LOWER TURNS COUNTERS EACH DRIVE A 6:1 VERNIER...WHICH DRIVE THE C1+C2 PI TUNED INPUT CAPS. THAT MEANS 0-300 INCREMENTS TO GET FROM MESHED TO UNMESHED.
|
On the 374A, 10 meters is just the Load cap. Its fixed tune.? So if you set the load cap to like 70 on the dial, You get instant 10, 15,20,40 and 80 with no tuning.??
I/we noticed the same thing on my 2x 3-1000Z amp.? Not sure if you remember.? I kept "walking" the coil and each time got more power. Eventually, increase stopped.? This makes a huge difference on higher bands.??
I also noticed this phenomenon can occur with the combo of Tune and load cap.? ?I like to "walk" the load cap in fixed degrees and peak the tune. There is a perfect spot. It will fall off on either side.
I am unsure why this happens.? It does happen on Most henry amps and the alphas. This does NOT occur on the SB220 for example. The load has one peak and its broad and soft.
The 2k4A was really bad about this. If you just dialed up the tune and load for peak or carrier. You would be sure to be way OFF.? Stepping the load control and adjusting tune again and you can find that sweet spot.
C
toggle quoted message
Show quoted text
Interestingly enough, after looking at the schematics for the 450/500/550 NT series of amplifiers,? they all use a PI network? on 160-10m.? ?BUT they use a lower, loaded Q.? ( more coil, less tune + load C).?
The alpha 78/ 374A etc, in broadband mode, ( and? also manual tune),? all use a PI-L..... same deal though, a lower loaded Q is used, when switching from 'manual tune'? to ....'broadband'.? ?In broadband mode, more L is used on 80-40-20-15m.?
The broadband feature on the alpha amps only works on 80-15m.? Strictly manual tune on 160+10m.?
?
I asked glen, AE0Q, the alpha fellow, why they didn't use the same deal on their newer amps (9500 / 8410).? He said the 78/374A? etc, had lower eff vs manual tuning.? So they switched to motor driven tune + load caps..and the bandswitch.?
?
Funny thing is, on one of my older 4-1000 amps, with the roller coil in it? ( and also my 3x3 with a roller).... when normal? Q used ( this is a PI), like 12-15, PO was good.? But then tried increasing the uh on the roller a bit ( and slightly less on the
tune + load caps)..and PO increased.? ?So repeated the process again, with more uh, less tune and load C..and again, PO increased.? Repeated several more times, in small increments, ( each time retuning the amp with the same drive level)...and PO kept on increasing,
Then no more PO with any further increases in uh.? ?It just flat lined with max PO, regardless of how much uh was dialed in.?
So I backed down the uh, until PO just started to drop off a few watts.... and left it there. This was all on 75m.? ?Same deal on the other bands.? ?The idea here is to use a lower Q...but just low enough to do the job.? ?Go too low, and PO stays the same,
(no more increase) even more broad banded, but I highly suspect the harmonic suppression is severely de-graded.?
?
There is NO spec for harmonic suppression in the online manual for the 450/500/550? (which also covers the NT versions).? ?
?
It would be interesting to know what the actual harmonic suppression is on each band on the NT versions.?
|
Interestingly enough, after looking at the schematics for the 450/500/550 NT series of amplifiers,? they all use a PI network? on 160-10m.? ?BUT they use a lower, loaded Q.? ( more coil, less tune + load C).?
The alpha 78/ 374A etc, in broadband mode, ( and? also manual tune),? all use a PI-L..... same deal though, a lower loaded Q is used, when switching from 'manual tune'? to ....'broadband'.? ?In broadband mode, more L is used on 80-40-20-15m.?
The broadband feature on the alpha amps only works on 80-15m.? Strictly manual tune on 160+10m.?
?
I asked glen, AE0Q, the alpha fellow, why they didn't use the same deal on their newer amps (9500 / 8410).? He said the 78/374A? etc, had lower eff vs manual tuning.? So they switched to motor driven tune + load caps..and the bandswitch.?
?
Funny thing is, on one of my older 4-1000 amps, with the roller coil in it? ( and also my 3x3 with a roller).... when normal? Q used ( this is a PI), like 12-15, PO was good.? But then tried increasing the uh on the roller a bit ( and slightly less on the tune + load caps)..and PO increased.? ?So repeated the process again, with more uh, less tune and load C..and again, PO increased.? Repeated several more times, in small increments, ( each time retuning the amp with the same drive level)...and PO kept on increasing, Then no more PO with any further increases in uh.? ?It just flat lined with max PO, regardless of how much uh was dialed in.?
So I backed down the uh, until PO just started to drop off a few watts.... and left it there. This was all on 75m.? ?Same deal on the other bands.? ?The idea here is to use a lower Q...but just low enough to do the job.? ?Go too low, and PO stays the same, (no more increase) even more broad banded, but I highly suspect the harmonic suppression is severely de-graded.?
?
There is NO spec for harmonic suppression in the online manual for the 450/500/550? (which also covers the NT versions).? ?
?
It would be interesting to know what the actual harmonic suppression is on each band on the NT versions.?
|
Checked it out. Radio - amp - swr/per meter - dummy load. All fine. He had a cluster _____ of coax, switches to switch different antennas to ??? I showed him the radio and amp are fine so he has to work on all the antennas and switching etc. Bob W4JFA?
I'll let you guys know what I find. I'll see it Tues eve. Bob W4JFA?
On Mon, Mar 25, 2024, 4:25 PM W7WRX < clark@...> wrote:
That is very odd. ..? I have owned several LK amps.? They will cover the entire band in the No tune.? The SWR needs to be fairly low however, Most people do not have an antenna that covers the entire band anyways.
Some models have a switch for 160 and 80 to cover the entire band.? Its two presets per on those bands.??
Also, my Alpha 374A works the same way. It also covers the entire band.
I think the reason why some people don't like them is?because they feel they are missing something by not tuning up to max power each time.
Who the hell wants to retune a damn amp 20 times an hour moving around from band to band and from low to high on the bands.? Nobody.? It ruins the fun of working DX.
These things are really nice and have a huge convenience factor. At the expense of some peak power output.?
Another huge advantage is some OPS, NO MATTER WHAT, will never tune the amp correctly.? They will mistune it, Burn it down, over and over and over. NT amps remove all of that.? The OM can just key down and operate with little risk of blowing the amp up.
For 1kw or so this kind of amp is really nice and fun to use.
C
All the LK series NT ( no tune) amps have several small load and tune capacitors. You must pre select the frequencies you want to operate on each band first.? Then you use the internal load and tune caps to load the amp up for those frequencies per band.
?Once you pre load the amp on the various bands you will only get a marginal excursion from the?selected frequency to an off frequency away from that.? You will never get?coverage of the bottom and top of the band.? As far as I¡¯m concerned these amps are only
good for ops that ONLY frequent certain frequencies on each band, like net control operators.? Anyone wanting the freedom of the whole band with full power output would never want these amps.
The loading process is pretty tedious because it has so be done with a long flat blade screwdriver and I think it needs to be done in a certain order but that¡¯s I¡¯m not sure of.
On Monday, March 25, 2024, 12:58 PM, Bob <W4JFABob@...> wrote:
Hi all,
Tomorrow I'm going to see a friend?that has some kind of problem with his LK-450 NT amp.
At this time I have no idea what the problem is due to inconsistent?information.
But I have a question, I've never worked on one of these but I'm assuming the network is
very broad banded and you only adjust a "fine tune" for your operating frequency.
My common sense tells me that inside there must be some kind of "broader" (lack of a better term) adjustment inside to get the network in the ballpark so a fine tune can dial it in.
I'm thinking that especially on 160 and 80/75 it would be critical to get it close for either the top of the bands or the bottom of the bands.
Am I on the right track? Also, is there any known common problems I should?be aware of?
Thanks all. Bob? W4JFA
|
I'll let you guys know what I find. I'll see it Tues eve. Bob W4JFA?
On Mon, Mar 25, 2024, 4:25 PM W7WRX < clark@...> wrote:
That is very odd. ..? I have owned several LK amps.? They will cover the entire band in the No tune.? The SWR needs to be fairly low however, Most people do not have an antenna that covers the entire band anyways.
Some models have a switch for 160 and 80 to cover the entire band.? Its two presets per on those bands.??
Also, my Alpha 374A works the same way. It also covers the entire band.
I think the reason why some people don't like them is?because they feel they are missing something by not tuning up to max power each time.
Who the hell wants to retune a damn amp 20 times an hour moving around from band to band and from low to high on the bands.? Nobody.? It ruins the fun of working DX.
These things are really nice and have a huge convenience factor. At the expense of some peak power output.?
Another huge advantage is some OPS, NO MATTER WHAT, will never tune the amp correctly.? They will mistune it, Burn it down, over and over and over. NT amps remove all of that.? The OM can just key down and operate with little risk of blowing the amp up.
For 1kw or so this kind of amp is really nice and fun to use.
C
All the LK series NT ( no tune) amps have several small load and tune capacitors. You must pre select the frequencies you want to operate on each band first.? Then you use the internal load and tune caps to load the amp up for those frequencies per band.
?Once you pre load the amp on the various bands you will only get a marginal excursion from the?selected frequency to an off frequency away from that.? You will never get?coverage of the bottom and top of the band.? As far as I¡¯m concerned these amps are only
good for ops that ONLY frequent certain frequencies on each band, like net control operators.? Anyone wanting the freedom of the whole band with full power output would never want these amps.
The loading process is pretty tedious because it has so be done with a long flat blade screwdriver and I think it needs to be done in a certain order but that¡¯s I¡¯m not sure of.
On Monday, March 25, 2024, 12:58 PM, Bob <W4JFABob@...> wrote:
Hi all,
Tomorrow I'm going to see a friend?that has some kind of problem with his LK-450 NT amp.
At this time I have no idea what the problem is due to inconsistent?information.
But I have a question, I've never worked on one of these but I'm assuming the network is
very broad banded and you only adjust a "fine tune" for your operating frequency.
My common sense tells me that inside there must be some kind of "broader" (lack of a better term) adjustment inside to get the network in the ballpark so a fine tune can dial it in.
I'm thinking that especially on 160 and 80/75 it would be critical to get it close for either the top of the bands or the bottom of the bands.
Am I on the right track? Also, is there any known common problems I should?be aware of?
Thanks all. Bob? W4JFA
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That is very odd. ..? I have owned several LK amps.? They will cover the entire band in the No tune.? The SWR needs to be fairly low however, Most people do not have an antenna that covers the entire band anyways.
Some models have a switch for 160 and 80 to cover the entire band.? Its two presets per on those bands.??
Also, my Alpha 374A works the same way. It also covers the entire band.
I think the reason why some people don't like them is?because they feel they are missing something by not tuning up to max power each time.
Who the hell wants to retune a damn amp 20 times an hour moving around from band to band and from low to high on the bands.? Nobody.? It ruins the fun of working DX.
These things are really nice and have a huge convenience factor. At the expense of some peak power output.?
Another huge advantage is some OPS, NO MATTER WHAT, will never tune the amp correctly.? They will mistune it, Burn it down, over and over and over. NT amps remove all of that.? The OM can just key down and operate with little risk of blowing the amp up.
For 1kw or so this kind of amp is really nice and fun to use.
C
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All the LK series NT ( no tune) amps have several small load and tune capacitors. You must pre select the frequencies you want to operate on each band first. ?Then you use the internal load and tune caps to load the amp up for those frequencies per band.
?Once you pre load the amp on the various bands you will only get a marginal excursion from the?selected frequency to an off frequency away from that. ?You will never get?coverage of the bottom and top of the band. ?As far as I¡¯m concerned these amps are only
good for ops that ONLY frequent certain frequencies on each band, like net control operators. ?Anyone wanting the freedom of the whole band with full power output would never want these amps.
The loading process is pretty tedious because it has so be done with a long flat blade screwdriver and I think it needs to be done in a certain order but that¡¯s I¡¯m not sure of.
On Monday, March 25, 2024, 12:58 PM, Bob <W4JFABob@...> wrote:
Hi all,
Tomorrow I'm going to see a friend?that has some kind of problem with his LK-450 NT amp.
At this time I have no idea what the problem is due to inconsistent?information.
But I have a question, I've never worked on one of these but I'm assuming the network is
very broad banded and you only adjust a "fine tune" for your operating frequency.
My common sense tells me that inside there must be some kind of "broader" (lack of a better term) adjustment inside to get the network in the ballpark so a fine tune can dial it in.
I'm thinking that especially on 160 and 80/75 it would be critical to get it close for either the top of the bands or the bottom of the bands.
Am I on the right track? Also, is there any known common problems I should?be aware of?
Thanks all. Bob? W4JFA
|
All the LK series NT ( no tune) amps have several small load and tune capacitors. You must pre select the frequencies you want to operate on each band first. ?Then you use the internal load and tune caps to load the amp up for those frequencies per band. ?Once you pre load the amp on the various bands you will only get a marginal excursion from the?selected frequency to an off frequency away from that. ?You will never get?coverage of the bottom and top of the band. ?As far as I¡¯m concerned these amps are only good for ops that ONLY frequent certain frequencies on each band, like net control operators. ?Anyone wanting the freedom of the whole band with full power output would never want these amps. The loading process is pretty tedious because it has so be done with a long flat blade screwdriver and I think it needs to be done in a certain order but that¡¯s I¡¯m not sure of.
On Monday, March 25, 2024, 12:58 PM, Bob <W4JFABob@...> wrote: Hi all,
Tomorrow I'm going to see a friend?that has some kind of problem with his LK-450 NT amp. At this time I have no idea what the problem is due to inconsistent?information.
But I have a question, I've never worked on one of these but I'm assuming the network is very broad banded and you only adjust a "fine tune" for your operating frequency.
My common sense tells me that inside there must be some kind of "broader" (lack of a better term) adjustment inside to get the network in the ballpark so a fine tune can dial it in. I'm thinking that especially on 160 and 80/75 it would be critical to get it close for either the top of the bands or the bottom of the bands.
Am I on the right track? Also, is there any known common problems I should?be aware of?
Thanks all. Bob? W4JFA
|
Bob
HaL Mandel