1-2 hrs max...per tube.
?
?
|
Hello ? Cooking the tubes. ? It was necessary to modify the tube polarization system. As shown previously, the HT power supply is floating relative to ground. This trick allows the cathode voltage (the filaments) to be modified relative to ground and as the grids are galvanically connected to ground, it allows the grid - cathode voltage to be adjusted. This is what happens in reception where the tubes are blocked with a grid - cathode voltage of -60V. ? To be able to positively polarize the grid relative to the cathode, in operational operation, the original diagram does not allow it. This diagram must therefore be modified. The positive polarization voltage of the grid can only come from an external source; it is shown as a green battery on the diagram ? 
? Obviously this involves some work including drilling the back panel to get the two wires out of the green source. I put in two female banana plugs and a bridge to place a short circuit in place of the auxiliary power supply to find the original diagram (0 V polarization). ? I remind you of the objective: to cook the anodes to red under a low anode voltage and a high current. All this to degas the tubes. It will certainly also be useful to improve the linearity by increasing the quiescent current which is possible since in France we are limited to 500 W HF (against the almost 2 kW that the PA can output). ? The first tests are done with a 230/230 transformer which unfortunately only makes 400 VA (it must not exceed 1.7 A on the secondary). The polarization is done from a 48 V transformer and a Graetz bridge rectifier. ? ·???????? With a polarization at 0 the plate voltage is at 688 volts and the quiescent current (since there is no HF in excitation) is 30 mA ·???????? With a polarization at 18 V DC (but it is rectified bi-alternation) the HT is 611 V, the plate current 300 mA (therefore 183 W) and the grid current (DC) 85 mA ·???????? With a polarization at 23 V DC the HT is at 593 V the plate current at 400 mA (237 W) the grid current 260 mA and I am at the limit of the transformer 1.6 A RMS ? That is not enough to make the plates red. ? I switched to a single 3-500Z tube. As a precaution, there is a load at the input and output but the system seems quite stable. ? Now it works ? Oddly enough, it only takes 20 Ω in series in the primary to bring the filament voltage back to 5.0 V. I plugged the hole caused by the missing lamp so as not to short-circuit the ventilation that I forced to the max. I placed a glass plate above the lamp box in order to leave the ventilation as when the cover is in place but being able to keep an eye on the anode of the tube (otherwise, you can't see the tubes). ? Two tests that give almost the same result: the anode in its lower part is dark red. ·???????? Bi-alternation rectified voltage on the grid Vg DC = 38 V Ig DC 110 mA plate current 390 mA under 592 V (231 W) secondary consumption: 359 VA ·???????? Bi-alternation rectified voltage + 6300 ?F capacitor so, basically DC on the grid Vg DC = 41.9 V Ig DC 120 mA plate current 400 mA under 584 V (234 W) secondary consumption: 389 VA ? I am limited by the 400 VA max of the 230/230 transformer supplying the voltage doubler. ? The measured values ??are questionable; I expected more difference when I added the capacitor. I am surprised that with 234 W on the anode, we are already in the dark red; the tube is given for 500 W of anode dissipation. I don't dare remove the anode radiator which also serves as a connector; I suppose it is this which prevents the entire anode from being red, from top to bottom. ? How long should I cook it for?
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Re: Ameritron AL-1500 Relay
I had a bad relay on my Al-811H and went this route. There’s a write up on DX World here:
?
I bought special teflon coated wire because of the heat in this area per the recommendations in the article.?
|
Re: Ameritron AL-1500 Relay
The AL1500 relay is a typical 3pdt 12v relay. ?There is nothing magical about it. ?There are many relays that can be subsidized for it if the original cannot be found. ?With Ameritron going out of business and parts supply drying up us hams are going to have to rely on our instincts to improvise to keep our gear working. ?Is the coil open on your relay? ?What seems to be the problem that not must be replaced?
On Sunday, February 23, 2025, 9:29 PM, DupyRail via groups.io <andytron434@...> wrote:
Try w8JI, CTR Engineering, he may have one.
73? Andy? K9ATX
On 2/23/2025 8:28 PM, Riki, K7NJ via
groups.io wrote:
The output relay in my Ameritron AL-1500 needs to be changed.
I checked with MFJ since they are still selling some Ameritron
replacement parts, but no luck.? From the user manual, this is
"RLY1" and its Ameritron part number is 408-6139.
?
This is a 3PDT, 10A, 12V DC through hole PCB mount relay. Two
of the poles are used for RF switching and the third is used for
another function. I've searched on Mouser, Digikey, Allied,
Newark and E-bay websites without finding anything that might be
a satisfactory replacement.
?
Ideally, an original replacement part would be found. This
would allay my concern about the contact materials which should
be gold or gold plated for the two NC RF contacts to ensure good
contact when receiving.?
?
Suggestions would be appreciated.
?
73 de Riki K7NJ?
?
--
"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
Broadcastify Train Scanner:
Youtube Channel:
|
Re: Ameritron AL-1500 Relay
Try w8JI, CTR Engineering, he may have one.
73? Andy? K9ATX
On 2/23/2025 8:28 PM, Riki, K7NJ via
groups.io wrote:
The output relay in my Ameritron AL-1500 needs to be changed.
I checked with MFJ since they are still selling some Ameritron
replacement parts, but no luck.? From the user manual, this is
"RLY1" and its Ameritron part number is 408-6139.
?
This is a 3PDT, 10A, 12V DC through hole PCB mount relay. Two
of the poles are used for RF switching and the third is used for
another function. I've searched on Mouser, Digikey, Allied,
Newark and E-bay websites without finding anything that might be
a satisfactory replacement.
?
Ideally, an original replacement part would be found. This
would allay my concern about the contact materials which should
be gold or gold plated for the two NC RF contacts to ensure good
contact when receiving.?
?
Suggestions would be appreciated.
?
73 de Riki K7NJ?
?
--
"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
Broadcastify Train Scanner:
Youtube Channel:
|
The output relay in my Ameritron AL-1500 needs to be changed. I checked with MFJ since they are still selling some Ameritron replacement parts, but no luck.? From the user manual, this is "RLY1" and its Ameritron part number is 408-6139.
?
This is a 3PDT, 10A, 12V DC through hole PCB mount relay. Two of the poles are used for RF switching and the third is used for another function. I've searched on Mouser, Digikey, Allied, Newark and E-bay websites without finding anything that might be a satisfactory replacement.
?
Ideally, an original replacement part would be found. This would allay my concern about the contact materials which should be gold or gold plated for the two NC RF contacts to ensure good contact when receiving.?
?
Suggestions would be appreciated.
?
73 de Riki K7NJ?
?
|
SVHFS Conference 2025, Call for Papers & Presentations
Here's an update on the SVHFS 2025 Conference;? Deadline for papers has been extended to March 17 Registration is open; details are in the attached file.
Thanks,
Robin Midgett K4IDC
|
WRX, with 200w drive, how much grid and plate current was it running? Bob W4JFA?
Which models had 4kv on the plate?? A Triode is only going to give 10 to 12 DB of gain.??
Man, I have worked on and rebuilt pretty much all of these amps and even the later 3KA with its HD supply won't do 2kw.? It does not have 4KV on plate.? I was curious which ones did.? It's rated at 3k input and the efficiency is pretty poor.??
Henry used horrible small Fil chokes in series.? These things need to be tossed in the trash.? They get super-hot and after years of use the permeability changes.? they get harder and harder to drive.
Its so bad that the Tubes won't have the same fil voltage on them. Thats why these things always have one bright tube.? One of the tubes can be a half to a full volt off!?
The last one I rebuilt made 1800W out on low bands but needed a 200W radio to get there. It really works hard there.? ?I put a fil transformer in with a proper Fil choke.? Now each tube is spot on for voltage.? The amp runs so much better.? The blower is way
too small.? I put a Dayton ball bearing blower it. Half the noise and twice the air.?
C
It’s a well known fact that the Ameritron AL80b can obtain 1kw output ?pep?with a single 3-500. They only run 3000 volts anode voltage.? The old Henry amps made prior to the power rule change were used in some Embassies.? For that use they were running
the same amps sold to hams.? The Henry amps had choke input filers and 4000 volts anode and the?plate voltage was rock steady.? Easily capable of 2kw pep output.? Naturally the ham manuals didn’t necessarily boast that sort of power and tune up instructions
were geared towards legal limits.? Hence the CW/SSB change in voltage.? Load to 1 kwdc input on CW Carrier) switch to SSB and talk and get 2kw pep input, but dare not let down in the SSB voltage!!! You’ll break the law.? When the 1500 pep putput came in, away
went the cw/SSB switches, not need for them anymore!!
On Friday, February 14, 2025, 12:51 PM, W7WRX <clark@...> wrote:
Which henry amps were rated at 2kw out Jim???
C
Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply.?
To getter older tubes, on the drake L7,? you can use the lower (1900 vdc) position, and temp shunt out any bias ( shunt out any series diodes used for bias)...and then apply a bit ( a few watts, 10-20 watts) of drive, and maladjust the tune control to put the
tank circuit off resonance...such that both tubes show some colour.?
|
Which models had 4kv on the plate?? A Triode is only going to give 10 to 12 DB of gain.??
Man, I have worked on and rebuilt pretty much all of these amps and even the later 3KA with its HD supply won't do 2kw.? It does not have 4KV on plate.? I was curious which ones did.? It's rated at 3k input and the efficiency is pretty poor.??
Henry used horrible small Fil chokes in series.? These things need to be tossed in the trash.? They get super-hot and after years of use the permeability changes.? they get harder and harder to drive.
Its so bad that the Tubes won't have the same fil voltage on them. Thats why these things always have one bright tube.? One of the tubes can be a half to a full volt off!?
The last one I rebuilt made 1800W out on low bands but needed a 200W radio to get there. It really works hard there.? ?I put a fil transformer in with a proper Fil choke.? Now each tube is spot on for voltage.? The amp runs so much better.? The blower is way
too small.? I put a Dayton ball bearing blower it. Half the noise and twice the air.?
C
toggle quoted message
Show quoted text
It’s a well known fact that the Ameritron AL80b can obtain 1kw output ?pep?with a single 3-500. They only run 3000 volts anode voltage. ?The old Henry amps made prior to the power rule change were used in some Embassies. ?For that use they were running
the same amps sold to hams. ?The Henry amps had choke input filers and 4000 volts anode and the?plate voltage was rock steady. ?Easily capable of 2kw pep output. ?Naturally the ham manuals didn’t necessarily boast that sort of power and tune up instructions
were geared towards legal limits. ?Hence the CW/SSB change in voltage. ?Load to 1 kwdc input on CW Carrier) switch to SSB and talk and get 2kw pep input, but dare not let down in the SSB voltage!!! You’ll break the law. ?When the 1500 pep putput came in, away
went the cw/SSB switches, not need for them anymore!!
On Friday, February 14, 2025, 12:51 PM, W7WRX <clark@...> wrote:
Which henry amps were rated at 2kw out Jim???
C
Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply.?
To getter older tubes, on the drake L7,? you can use the lower (1900 vdc) position, and temp shunt out any bias ( shunt out any series diodes used for bias)...and then apply a bit ( a few watts, 10-20 watts) of drive, and maladjust the tune control to put the
tank circuit off resonance...such that both tubes show some colour.?
|
The Tokyo High power HL2K? with 3-500s was also such a amp. It had proper cooling(fully pressurised) On 240 VAC it could easily hit 2KW pep even though it was rated for 1.2KW PEP. Much like the TL922 which can? easily hit 1.5KW pep on 20 metres and below. The Tokyo high power HL2K was a popular RTTY? contest amp because it would not break down or melt parts and pins because of proper cooling. I think Amp Supply also had a heavy duty 3-500Z 3 or 4 holer, I cant remember.?
|
It’s a well known fact that the Ameritron AL80b can obtain 1kw output ?pep?with a single 3-500. They only run 3000 volts anode voltage. ?The old Henry amps made prior to the power rule change were used in some Embassies. ?For that use they were running the same amps sold to hams. ?The Henry amps had choke input filers and 4000 volts anode and the?plate voltage was rock steady. ?Easily capable of 2kw pep output. ?Naturally the ham manuals didn’t necessarily boast that sort of power and tune up instructions were geared towards legal limits. ?Hence the CW/SSB change in voltage. ?Load to 1 kwdc input on CW Carrier) switch to SSB and talk and get 2kw pep input, but dare not let down in the SSB voltage!!! You’ll break the law. ?When the 1500 pep putput came in, away went the cw/SSB switches, not need for them anymore!!
On Friday, February 14, 2025, 12:51 PM, W7WRX <clark@...> wrote:
Which henry amps were rated at 2kw out Jim???
C
Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply.?
To getter older tubes, on the drake L7,? you can use the lower (1900 vdc) position, and temp shunt out any bias ( shunt out any series diodes used for bias)...and then apply a bit ( a few watts, 10-20 watts) of drive, and maladjust the tune control to put the
tank circuit off resonance...such that both tubes show some colour.?
|
Which henry amps were rated at 2kw out Jim???
C
toggle quoted message
Show quoted text
Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply.?
To getter older tubes, on the drake L7,? you can use the lower (1900 vdc) position, and temp shunt out any bias ( shunt out any series diodes used for bias)...and then apply a bit ( a few watts, 10-20 watts) of drive, and maladjust the tune control to put the
tank circuit off resonance...such that both tubes show some colour.?
|
Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply.?
To getter older tubes, on the drake L7,? you can use the lower (1900 vdc) position, and temp shunt out any bias ( shunt out any series diodes used for bias)...and then apply a bit ( a few watts, 10-20 watts) of drive, and maladjust the tune control to put the tank circuit off resonance...such that both tubes show some colour.?
|
Hi Mike
?
I'll try that transformer thing when I get to that point..
?
thanks
?
don
|
I would be interested to know how you interface the TOA amp to the
modulator tubes in my case using a pair TZ40s?
73
Mike VK2AMF
?
At 02:18 AM 6/02/2025, you wrote:
toggle quoted message
Show quoted text
I would rip all the front-end
tubes out and drive it with a 10W TOA amplifier. You can get these cheap
on ebay and other websites.? $20 to $30 bucks. They have 4/8 and a
70v output with balanced and unbalanced and a Mic input. These work great
to drive a pair of modulators.? They also have bass and
treble.? I use several here for that purpose.
The 813s as Chuck said, wont play well on higher bands. I would not use
those. A 4-400 single is the way to go here.? You can modulate the
screen with a Dropping resistor off the plate.? No screen
supply.??? You could use the 813s as modulators
though!
Technically you won't even need a bias supply for the final. If you build
a simple sequencer with a few relays, Diodes between the coils and caps
to set delay.? You can ensure Drive appears on the 4-400 before its
keyed with B plus.? Set drive to -183 volts using a meter and a
choke right to the grid.? This will be 10 to 12 MA.?
You could Grid leak it, OR build an adjustable bias supply with negative
-75 to - 175 adjustability. I would not bother. One of my rigs has been
running 20 years with No Bias.? It has a simple over current
relay.? If drive where to disappear, it just trips.
A single will truck along at 500 to 600 W carrier No problem.
C
From: [email protected]
<[email protected]> on behalf of kc1at via groups.io
<kc1at@...>
Sent: Wednesday, February 5, 2025 5:28 AM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Dilemma
?
WOW....thanks so much for the input. Let me try to answer some of
the questions
?
Oops....its not a 350 watt modulator its a 300 watts. The thing is a
monster. Has 4 - 12au7s into a pair of 6146's then into a pair of 6080s
then the pair of 811s into a CVM-4. Can't figure out the 12AU7s. Lots of
components missing or dead ended. I'll probably just make a new front end
for it. Seems like an over kill to me.
?
truth is I've been leaning towards the 4-400 with the 813s as a back
up
?
Can drive it with my 32v3. (one of 3) That's another disease i have
"Collins stuff. "
?
Let me drag out my 4-400 schematics that I've collected over the last
year or so.
?
don
Mike Fleetwood
Canberra Australia and Sidcup UK.
Worldwide email address
is:?????
mfleetwood@...
|
Don, ????????? I’m not sure if you know this, but you can use the 70.7V output to drive a 600Ω input. 5K/10KΩ P-P to 600Ω transformers are usually available. Turn them around and drive the grids of your modulator using your Bogen as a speech amp. I have a Bogen 60MX driving the grids of my 805s. ? Mod-U-Lator, Mike(y)/W3SLK ? ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of kc1at via groups.io
Sent: Wednesday, February 5, 2025 4:15 PM
To: [email protected]
Subject: Re: [ham-amplifiers] Dilemma ? Thats what I'm leaning towards now. Scrap the input with all those 12AU7s and do something else. Reverse engineering that circuit seems fruitless . Not sure it even worked when built. Took a look at those TOA amps. I had no idea there were so many of them. Found a Bogen amp in my junk box. also has a 4-8 and 70.7 output with a cheap 4 band equalizer. Gonna drag that out to see if it has any hope of working. Going into my iron now to see if I can support? a single 4-400. thanks everyone for the help
|
Thats what I'm leaning towards now. Scrap the input with all those 12AU7s and do something else. Reverse engineering that circuit seems fruitless . Not sure it even worked when built.
?
Took a look at those TOA amps. I had no idea there were so many of them. Found a Bogen amp in my junk box. also has a 4-8 and 70.7 output with a cheap 4 band equalizer. Gonna drag that out to see if it has any hope of working.
?
Going into my iron now to see if I can support? a single 4-400.
?
thanks everyone for the help
?
don
|
I would rip all the front-end tubes out and drive it with a 10W TOA amplifier. You can get these cheap on ebay and other websites.? $20 to $30 bucks. They have 4/8 and a 70v output with balanced and unbalanced and a Mic input. These work great to drive a pair
of modulators.? They also have bass and treble.? I use several here for that purpose.
The 813s as Chuck said, wont play well on higher bands. I would not use those. A 4-400 single is the way to go here.? You can modulate the screen with a Dropping resistor off the plate.? No screen supply.? ? You could use the 813s as modulators though!
Technically you won't even need a bias supply for the final. If you build a simple sequencer with a few relays, Diodes between the coils and caps to set delay.? You can ensure Drive appears on the 4-400 before its keyed with B plus.? Set drive to -183 volts
using a meter and a choke right to the grid.? This will be 10 to 12 MA.??
You could Grid leak it, OR build an adjustable bias supply with negative -75 to - 175 adjustability. I would not bother. One of my rigs has been running 20 years with No Bias.? It has a simple over current relay.? If drive where to disappear, it just trips.
A single will truck along at 500 to 600 W carrier No problem.
C
toggle quoted message
Show quoted text
WOW....thanks so much for the input. Let me try to answer some of the questions
?
Oops....its not a 350 watt modulator its a 300 watts. The thing is a monster. Has 4 - 12au7s into a pair of 6146's then into a pair of 6080s then the pair of 811s into a CVM-4. Can't figure out the 12AU7s. Lots of components missing or dead ended. I'll
probably just make a new front end for it. Seems like an over kill to me.
?
truth is I've been leaning towards the 4-400 with the 813s as a back up
?
Can drive it with my 32v3. (one of 3) That's another disease i have "Collins stuff. "
?
Let me drag out my 4-400 schematics that I've collected over the last year or so.
?
don
|
WOW....thanks so much for the input. Let me try to answer some of the questions
?
Oops....its not a 350 watt modulator its a 300 watts. The thing is a monster. Has 4 - 12au7s into a pair of 6146's then into a pair of 6080s then the pair of 811s into a CVM-4. Can't figure out the 12AU7s. Lots of components missing or dead ended. I'll probably just make a new front end for it. Seems like an over kill to me.
?
truth is I've been leaning towards the 4-400 with the 813s as a back up
?
Can drive it with my 32v3. (one of 3) That's another disease i have "Collins stuff. "
?
Let me drag out my 4-400 schematics that I've collected over the last year or so.
?
don
|
Sounds good.? I have a HB rig with two 4-400s modulated by 304TLs.? It runs 10 to 160.? I have had it on 10 and 20 recently. Through a 4 elment mosley. Over 300 contacts on 10-meter AM. If you want to have a QSO sometime, that would be great!? ?
C
toggle quoted message
Show quoted text
Well, not much on the air these days, mostly on 160M, 75M, and sometimes on 40M in the so called “AM windows”
?
Spending much more time on other infinite money sinks like olde cars and astronomy.
?
More hobbies as I get older and things I always wanted to do as a kid but couldn’t afford…now I can..
?
AS my father said, “I came into this world penniless, and I’m leaving it that way”? ??I’m working on that premise!
?
-Chuck K1KW
?
?
Hey Chuck.? Have not had a QSO is a long time. Where are you hanging out these days on AM?
Grid drive one 4-400 with bias and screen voltage.? Then you can run Class C for plate modulation and bias it for AB1 or AB2 operation for SSB amplifier
mode.
?
A Johnson ranger or similar power level ?“boatanchor” would make an ideal driver for the Class C operation.? Lots of schematics available in earlier ARRL
publications for such a set up. I think there was a 4-400A amp in several of the ARRL handbooks from the 1960’s.
?
813’s get squirrely on 15M and above and can be tamed but efficiency drops a bit.
?
What are the modulator tubes and which modulation transformer are you going to use?
?
I’ve built several AM rigs in the past ten years and have pictures of them on my QRZ.com page.? Check out the 4-400A rig I designed and built.? Also the
813 rig.
?
-Chuck K1KW
?
From:
[email protected]
[mailto:[email protected]] On Behalf Of kc1at via groups.io
Sent: Tuesday, February 04, 2025 6:35 AM
To: [email protected]
Subject: [ham-amplifiers] Dilemma
?
Over the years I've collected parts to build an amplifier. Life got in the way during most those years but now I find myself with the time and ambition to build an amplifier for my boatanchors.
As far as bottles are concerned I have a bunch of 813s a 3-400Z,. couple of 4-400s and of course the usual 811s, 807s, 6146s........Got plenty of iron for a power supply up to 3kv.
Need some direction as to which way to go.? I operate 40 thru 10. Have a soft spot for AM. (yes I'm old) but do CW and SSB.
Finishing up a 350 watt modulator.
OR should I forget all this stuff sell it and buy an amplifier.
|
Elijah
Robin Midgett
Bob