Does anyone know of a drop in replacement for the relay in a L4B?
Or do you know the specs? Drake manuals give little to no information.
?
Ronnie W5SUM
|
The Tr7 is really pretty simple to troubleshoot and repair. There's a lot of people out there more than capable. it's not just two or three in the whole world.
On Monday, January 20, 2025 at 09:43:14 PM EST, David via groups.io <david.w5xu@...> wrote:
I have a Hunter Bandit?on the bench.? I will check that out as well. David Assaf III W5XU, VP8RXU ?
Interesting. I've never seen that configuration. Granted, I have not worked on every amp out there. But all I have seen is the single reverse biased diode. My two Alpha amps have it, and W8JI also shows a single diode. I'll stick with the single diode method.
On Mon, 20 Jan 2025 00:38:59 -0800
"Jim VE7RF via " <jim.thom=[email protected]> wrote:
> On Sun, Jan 19, 2025 at 03:41 PM, Jim Shorney wrote:
>
> >? ?
> > >Interesting video but his glitch diode configuration has me puzzled. He?
> > complains (rightly so) that the B- was returned to the chassis but
> > connects a reversed diode pair in which one of the diodes returns the B-
> > to the >chassis? The glitch diode implementations I have seen use only a
> > reverse biased diode from B- to chassis ground. Am I missing something??
>
> With the 2nd diode installed (rvs connected pair).....the pair? ensures the B-? ?can't wander more than? +/-? .7 vdc? ?from chassis potential.? ?In the old days, something like a 10 ohm resistor from B- to chassis? would accomplish the same thing.? The concept in both cases was to float the B- from chassis potential just enough..... to be able to measure plate and grid current.? The issue with the 10 ohm resistor is if the anode arcs to the grid, or chassis, the fault current path is up from the chassis, through the resistor.... and back to the B- of the filter caps..... completing the loop.....and of course the resistor grenades.
>
> With any anode to grid arc, or B+ to chassis arc, only one diode is required ( UN-banded end? facing the chassis).? ?I install the 2nd diode just to ensure the B-? can never wander more than +/- .7 vdc from the chassis.
>
> With any GG amp that has a grid over current circuit in it, it will not function correctly, since the 2nd diode is electrically in parallel with the? typ small value resistor used in the grid over current assy.... ( typ wired in series with the negative end of grid meter / grid shunt..... and chassis).? ?The V drop across the low value resistor is now in parallel with the 2nd diode, biasing the 2nd diode on.? Then grid current flows? up from the chassis....and through the 2nd diode........ instead of up through from the chassis.... and through the small value grid sense resistor...... which results in low or no? grid current readings, even though plate current reads normal, and PO is normal.
>
> That's why only one diode is used on ameritron amps that have the grid over current scheme installed.? ?In older books, you will see the rvs connected pair of diodes across? both the grid and plate current meter..... and that scheme still works......? ?with or without the grid overcurrent sense circuit installed.
>
> In the L4B in question, the customer paid for packing and shipping to Ron, plus a helluva lot of money up front, only to be told it was unrepairable...and Ron wanted to keep the amp? and the HV supply....and the money.? Customer was told when the plate xfmr heats up, it shorts out.? Nothing wrong with the plate xfmr.? It's all fixed now.....plus the customer got his money back from Ron.? ? Dunno, but Ron might be starting to lose it.? ?And that could result in a dangerous scenario, esp with +2650vdc? involved.
>
>
>
>
>
--
73
-Jim
NU0C
|
Re: T-4XC has a "condition"
Hi guys,
?
It¡¯s been a few weeks since we had an update. If you go back and review the thread most of the concern was with the T-4XC tune up procedure, knob left, knob right, never heard
of that¡..
?
My original thought was the bias setting was never correct from the power supply. So I bought an upgrade two board kit and gave the AC-4 new life. Yes, I had a problem and
that¡¯s the reason for the delay.
?
Today I received a new fuse, 5A slo blo and hooked up the rigs and¡. First order was to run the POTA list on 20 meters. Got every one of them. Then realized the grey line was
here so went to 15 meters and worked Nori in Japan, no problem.
?
Conclusion: I could not correctly tune the T-4XC because the bias was wrong in the PS.
?
Thank you for all the help.
?
Dean/ N2TNN
?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]>
On Behalf Of Gary WB6OGD via groups.io
Sent: Friday, January 3, 2025 7:32 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] T-4XC has a "condition"
?
On Fri, Jan 3, 2025 at 12:28 PM, VE7PS wrote:
I can't experiment with one of my own rigs today or tomorrow, but I'll be able to do that likely on Sunday.? I am now anxious to see if I can duplicate what you are seeing with the RF Tune rotated
clockwise into the high end of the 10m band setting.
If there is a difference (there should NOT be), it probably indicates the need for neutralization.? 10meters is where the final can most easily
break into oscillation if not neutralized properly (and with a correctly working transmitter).
I would set the bias on the lower bands, and on SSB with the gain at zero... and after I nulled the carrier!? If the radio is working correctly,
that bias point should hold on all bands, if it doesn't something is wrong.
|
I have a Hunter Bandit?on the bench.? I will check that out as well. David Assaf III W5XU, VP8RXU ?
Interesting. I've never seen that configuration. Granted, I have not worked on every amp out there. But all I have seen is the single reverse biased diode. My two Alpha amps have it, and W8JI also shows a single diode. I'll stick with the single diode method.
On Mon, 20 Jan 2025 00:38:59 -0800
"Jim VE7RF via " <jim.thom=[email protected]> wrote:
> On Sun, Jan 19, 2025 at 03:41 PM, Jim Shorney wrote:
>
> >? ?
> > >Interesting video but his glitch diode configuration has me puzzled. He?
> > complains (rightly so) that the B- was returned to the chassis but
> > connects a reversed diode pair in which one of the diodes returns the B-
> > to the >chassis? The glitch diode implementations I have seen use only a
> > reverse biased diode from B- to chassis ground. Am I missing something??
>
> With the 2nd diode installed (rvs connected pair).....the pair? ensures the B-? ?can't wander more than? +/-? .7 vdc? ?from chassis potential.? ?In the old days, something like a 10 ohm resistor from B- to chassis? would accomplish the same thing.? The concept in both cases was to float the B- from chassis potential just enough..... to be able to measure plate and grid current.? The issue with the 10 ohm resistor is if the anode arcs to the grid, or chassis, the fault current path is up from the chassis, through the resistor.... and back to the B- of the filter caps..... completing the loop.....and of course the resistor grenades.
>
> With any anode to grid arc, or B+ to chassis arc, only one diode is required ( UN-banded end? facing the chassis).? ?I install the 2nd diode just to ensure the B-? can never wander more than +/- .7 vdc from the chassis.
>
> With any GG amp that has a grid over current circuit in it, it will not function correctly, since the 2nd diode is electrically in parallel with the? typ small value resistor used in the grid over current assy.... ( typ wired in series with the negative end of grid meter / grid shunt..... and chassis).? ?The V drop across the low value resistor is now in parallel with the 2nd diode, biasing the 2nd diode on.? Then grid current flows? up from the chassis....and through the 2nd diode........ instead of up through from the chassis.... and through the small value grid sense resistor...... which results in low or no? grid current readings, even though plate current reads normal, and PO is normal.
>
> That's why only one diode is used on ameritron amps that have the grid over current scheme installed.? ?In older books, you will see the rvs connected pair of diodes across? both the grid and plate current meter..... and that scheme still works......? ?with or without the grid overcurrent sense circuit installed.
>
> In the L4B in question, the customer paid for packing and shipping to Ron, plus a helluva lot of money up front, only to be told it was unrepairable...and Ron wanted to keep the amp? and the HV supply....and the money.? Customer was told when the plate xfmr heats up, it shorts out.? Nothing wrong with the plate xfmr.? It's all fixed now.....plus the customer got his money back from Ron.? ? Dunno, but Ron might be starting to lose it.? ?And that could result in a dangerous scenario, esp with +2650vdc? involved.
>
>
>
>
>
--
73
-Jim
NU0C
|
Interesting. I've never seen that configuration. Granted, I have not worked on every amp out there. But all I have seen is the single reverse biased diode. My two Alpha amps have it, and W8JI also shows a single diode. I'll stick with the single diode method. On Mon, 20 Jan 2025 00:38:59 -0800 "Jim VE7RF via groups.io" <jim.thom@...> wrote: On Sun, Jan 19, 2025 at 03:41 PM, Jim Shorney wrote:
Interesting video but his glitch diode configuration has me puzzled. He complains (rightly so) that the B- was returned to the chassis but
connects a reversed diode pair in which one of the diodes returns the B-
to the >chassis? The glitch diode implementations I have seen use only a
reverse biased diode from B- to chassis ground. Am I missing something? With the 2nd diode installed (rvs connected pair).....the pair? ensures the B-? ?can't wander more than? +/-? .7 vdc? ?from chassis potential.? ?In the old days, something like a 10 ohm resistor from B- to chassis? would accomplish the same thing.? The concept in both cases was to float the B- from chassis potential just enough..... to be able to measure plate and grid current.? The issue with the 10 ohm resistor is if the anode arcs to the grid, or chassis, the fault current path is up from the chassis, through the resistor.... and back to the B- of the filter caps..... completing the loop.....and of course the resistor grenades.
With any anode to grid arc, or B+ to chassis arc, only one diode is required ( UN-banded end? facing the chassis).? ?I install the 2nd diode just to ensure the B-? can never wander more than +/- .7 vdc from the chassis.
With any GG amp that has a grid over current circuit in it, it will not function correctly, since the 2nd diode is electrically in parallel with the? typ small value resistor used in the grid over current assy.... ( typ wired in series with the negative end of grid meter / grid shunt..... and chassis).? ?The V drop across the low value resistor is now in parallel with the 2nd diode, biasing the 2nd diode on.? Then grid current flows? up from the chassis....and through the 2nd diode........ instead of up through from the chassis.... and through the small value grid sense resistor...... which results in low or no? grid current readings, even though plate current reads normal, and PO is normal.
That's why only one diode is used on ameritron amps that have the grid over current scheme installed.? ?In older books, you will see the rvs connected pair of diodes across? both the grid and plate current meter..... and that scheme still works......? ?with or without the grid overcurrent sense circuit installed.
In the L4B in question, the customer paid for packing and shipping to Ron, plus a helluva lot of money up front, only to be told it was unrepairable...and Ron wanted to keep the amp? and the HV supply....and the money.? Customer was told when the plate xfmr heats up, it shorts out.? Nothing wrong with the plate xfmr.? It's all fixed now.....plus the customer got his money back from Ron.? ? Dunno, but Ron might be starting to lose it.? ?And that could result in a dangerous scenario, esp with +2650vdc? involved.
-- 73 -Jim NU0C
|
Thanks Jim, I think the IFR1200S reads 150 watts, but you're right.?? I should get a dry dummy load for the shack. 73
Be careful with that. I blew the load in my IFR 1000 with a TR7. It doesn't take long at full power.
On Mon, 20 Jan 2025 21:13:55 -0500
"Jay? W6CJ via " <lastradioman=[email protected]> wrote:
> Thanks Tim.
> It was a noninductive load in an IFR-1200S service monitor.
> 73
> Jay
--
73
-Jim
NU0C
|
Be careful with that. I blew the load in my IFR 1000 with a TR7. It doesn't take long at full power. On Mon, 20 Jan 2025 21:13:55 -0500 "Jay W6CJ via groups.io" <lastradioman@...> wrote: Thanks Tim.
It was a noninductive load in an IFR-1200S service monitor.
73
Jay -- 73 -Jim NU0C
|
Richard, Thanks for the info and drive levels document.?? I'll check that out.? I have a service monitor with basic scope functions. 73, Jay
(OT: my QTH is 4-5 miles SW of the nearest part of the Eaton fire at its peak.? We had masks on indoors and air purifiers at max for two days)
? ? I suggest going over the RF and mixer stage adjustments. I am going
more by experience with a T4XB but they are not much different from the
C. It is normal for the power output to be slightly lower on the high
bands than at 80 and 40 but those two should be about the same. If you
have run out of range on the trimmer caps but the slugs are where they
should be try using a slightly lower or higher frequency for the
adjustments. This is often necessary for 160.? Note that the power in
TUNE is different than the power in CW. The ALC limits maximum power to
about 120 watts but does not operate in Tune or CW. For CW you may be
able to get as much as 150 watts out but its usually best to tune in
TUNE for slightly lower power. On 10 meters, with RF and mixer adjusted
properly you should be getting around 90 watts.
? ? ?Test in CW mode and see what you get.
? ? ?I am attaching a document with T4XB drive levels on it. The C
should be about the same. It may help. I don't have a note as to the
source of this but thought it worth saving.
? ? ?It is very strange that even though I drive quite a lot I have seen
very little sign of the fires. L.A. is a very strange city. Dystopia
indeed.
On 1/20/2025 4:41 PM, Jay W6CJ via wrote:
> Group,
> While making a cheat sheet for pre-tuning my T4XC (see attached excel
> doc), I noticed low power out on some frequencies - especially 3550
> Khz.? ?What is normal power output on the traditional & WARC bands?
>
> A W4 wattmeter was used.
>
> 73 from the LA dystopia? ? ?
> Jay
> W6CJ
>
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Thanks Tim. It was a noninductive load in an IFR-1200S service monitor. 73 Jay
Jay I'd say all is normal or close to it other than 3550. Now was that into a 50 ohm? nonrestrictive load?
Nothing to be concerned about actually no one will tell the difference on the receive end.
Tim
WB8UHZ
On Monday, January 20, 2025 at 07:42:10 PM EST, Jay W6CJ via <lastradioman= [email protected]> wrote:
Group, While making a cheat sheet for pre-tuning my T4XC (see attached excel doc), I noticed low power out on some frequencies - especially 3550 Khz.? ?What is normal power output on the traditional & WARC bands?
A W4 wattmeter was used.
73 from the LA dystopia? ? ?? Jay W6CJ
|
I suggest going over the RF and mixer stage adjustments. I am going more by experience with a T4XB but they are not much different from the C. It is normal for the power output to be slightly lower on the high bands than at 80 and 40 but those two should be about the same. If you have run out of range on the trimmer caps but the slugs are where they should be try using a slightly lower or higher frequency for the adjustments. This is often necessary for 160. Note that the power in TUNE is different than the power in CW. The ALC limits maximum power to about 120 watts but does not operate in Tune or CW. For CW you may be able to get as much as 150 watts out but its usually best to tune in TUNE for slightly lower power. On 10 meters, with RF and mixer adjusted properly you should be getting around 90 watts.
Test in CW mode and see what you get.
I am attaching a document with T4XB drive levels on it. The C should be about the same. It may help. I don't have a note as to the source of this but thought it worth saving.
It is very strange that even though I drive quite a lot I have seen very little sign of the fires. L.A. is a very strange city. Dystopia indeed.
toggle quoted message
Show quoted text
On 1/20/2025 4:41 PM, Jay W6CJ via groups.io wrote: Group,
While making a cheat sheet for pre-tuning my T4XC (see attached excel doc), I noticed low power out on some frequencies - especially 3550 Khz.? ?What is normal power output on the traditional & WARC bands?
A W4 wattmeter was used.
73 from the LA dystopia? ? ?
Jay
W6CJ
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Jay I'd say all is normal or close to it other than 3550. Now was that into a 50 ohm? nonrestrictive load?
Nothing to be concerned about actually no one will tell the difference on the receive end.
Tim
WB8UHZ
On Monday, January 20, 2025 at 07:42:10 PM EST, Jay W6CJ via groups.io <lastradioman@...> wrote:
Group, While making a cheat sheet for pre-tuning my T4XC (see attached excel doc), I noticed low power out on some frequencies - especially 3550 Khz.? ?What is normal power output on the traditional & WARC bands?
A W4 wattmeter was used.
73 from the LA dystopia? ? ?? Jay W6CJ
|
Group, While making a cheat sheet for pre-tuning my T4XC (see attached excel doc), I noticed low power out on some frequencies - especially 3550 Khz.? ?What is normal power output on the traditional & WARC bands?
A W4 wattmeter was used.
73 from the LA dystopia? ? ?? Jay W6CJ
|
Re: TR-4C Problems with 28.0 and 28.5 bands
This is a long-shot.
Try adjusting T1.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Monday, January 20th, 2025 at 3:40 PM, Dave KD5FX via groups.io <land.dave@...> wrote:
Yes, I have tried switching the Xtals all around. I first put the 28.0 Xtal in the 29.1 slot and got nothing, no receive. I then put the 28.5 Xtal in 29.1 and got the same, nothing. Then I put the 29.1 Xtal (which works OK when in the 29.1 slot) in the 28.0 and 28.5 slots and got nothing. So that was strange, the problem didn't move, still no receive on 28.0 and 28.5.?
A friend suggest using my SDR to listen to the V1 oscillator freq and see what I was getting. So I made a sampler probe with a short piece of coax and a small coil of wire and only needed to get it close to V1 to get a strong signal.? I started with 7.0 band which is 21.5 MHz and the 21 band which is 35.5 MHz and got good strong signals on the SDR with both bands. On 29.1 I am getting a strong signal at 43.6 MHz but 28.5 (43.0 MHz) and 28.0 (42.5) had nothing. So I set it to 28.5 band and tweaked the L5 control I was soon able to get a signal near the proper 43.0 MHz but not exactly, it would be just below that and then as I turned it just a bit more it would skip over and be above 43.0 by a few KHz. I could never get it right on 43.0. However, when I hooked the Drake back up to an outside antenna I am now getting SSB signals across that 28.5 band! But the dial is off by about 20 KHz. So that's better than nothing on that band! 29.1 band is still working normally and 28.0 band is not working at all, I could never get it to tune up and oscillate. Perhaps that Xtal is bad.?
I temped to just quit there, it's working except for 28.0 band.?
73, Dave KD5FX
?
|
Re: TR-4C Problems with 28.0 and 28.5 bands
Yes, I have tried switching the Xtals all around. I first put the 28.0 Xtal in the 29.1 slot and got nothing, no receive. I then put the 28.5 Xtal in 29.1 and got the same, nothing. Then I put the 29.1 Xtal (which works OK when in the 29.1 slot) in the 28.0 and 28.5 slots and got nothing. So that was strange, the problem didn't move, still no receive on 28.0 and 28.5.?
A friend suggest using my SDR to listen to the V1 oscillator freq and see what I was getting. So I made a sampler probe with a short piece of coax and a small coil of wire and only needed to get it close to V1 to get a strong signal.? I started with 7.0 band which is 21.5 MHz and the 21 band which is 35.5 MHz and got good strong signals on the SDR with both bands. On 29.1 I am getting a strong signal at 43.6 MHz but 28.5 (43.0 MHz) and 28.0 (42.5) had nothing. So I set it to 28.5 band and tweaked the L5 control I was soon able to get a signal near the proper 43.0 MHz but not exactly, it would be just below that and then as I turned it just a bit more it would skip over and be above 43.0 by a few KHz. I could never get it right on 43.0. However, when I hooked the Drake back up to an outside antenna I am now getting SSB signals across that 28.5 band! But the dial is off by about 20 KHz. So that's better than nothing on that band! 29.1 band is still working normally and 28.0 band is not working at all, I could never get it to tune up and oscillate. Perhaps that Xtal is bad.?
I temped to just quit there, it's working except for 28.0 band.?
73, Dave KD5FX
?
|
Good point. I¡¯d find a way of using the slots.?
I don¡¯t mind using the Hayseed kits for sets that I¡¯m keeping. I am, however, beginning to use my Sprague TO-6 to test the caps after I unhook the wires. I have found that most of the receivers and earlier TR-4¡¯s have can caps in them that still pass testing by a comfortable margin.?
The most troublesome can caps I have found are on the TR-4C(any) and the T-4(any). Any TR-4C sets that cross my bench will get new caps if they don¡¯t have them replaced already.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Jan 20, 2025 at 08:46, John K5MO via groups.io < johnk5mo@...> wrote:
I'm planning to use a bit of silicone and a soldered ground.
John K5MO
I saw that small PC board with individual radial lead capacitor kit available on eBay
but after studying the PC board it appeared that 2 holes needed to be drilled in the
2B chassis. While I'm sure the small PC board cap kit works after installing it on the 2B
chassis, having to drill 2 holes in the chassis to mount the small PC board was not
something I was willing to do. I used the hayseedhamfest Drake 2B capacitor kit that
worked very well and didn't require drilling holes in the chassis.
?
73
Mike W5RKL
?
|
Re: 4-Line Crystals for 10M
That was me and thank you!
Bill N1WL
? ?William Losefsky? ?????????
On Monday, January 20, 2025 at 12:04:34 AM EST, n4buq <n4buq@...> wrote:
I think someone was having problems with two of the 10M bands with a 4-line rig recently.? I happened to see these and thought I'd pass the ad along:
Thanks,
Barry - N4BUQ
|
I'm planning to use a bit of silicone and a soldered ground.
John K5MO
I saw that small PC board with individual radial lead capacitor kit available on eBay
but after studying the PC board it appeared that 2 holes needed to be drilled in the
2B chassis. While I'm sure the small PC board cap kit works after installing it on the 2B
chassis, having to drill 2 holes in the chassis to mount the small PC board was not
something I was willing to do. I used the hayseedhamfest Drake 2B capacitor kit that
worked very well and didn't require drilling holes in the chassis.
?
73
Mike W5RKL
?
|
I saw that small PC board with individual radial lead capacitor kit available on eBay
but after studying the PC board it appeared that 2 holes needed to be drilled in the
2B chassis. While I'm sure the small PC board cap kit works after installing it on the 2B
chassis, having to drill 2 holes in the chassis to mount the small PC board was not
something I was willing to do. I used the hayseedhamfest Drake 2B capacitor kit that
worked very well and didn't require drilling holes in the chassis.
?
73
Mike W5RKL
?
|
Re: Using an R7A with a TR7A
Thanks to all for the documents!
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Jan 20, 2025 at 03:07, Karl du Roi, DK7AL < dk7al@...> wrote: Steve,
have you already seen and checked this piece of information regarding
building an interconnection cable between Drake TR7 and R7:
https://www.dl7maj.de/TR7-R7-cable.pdf
Best regards.
Karl, DK7AL
Am 19.01.25 um 23:13 schrieb Steve Wedge, W1ES/4 via groups.io:
> Folks ¡ª
>
> I have someone asking me to get their R7 to work with a TR7. I just want to make sure that the connectors and cables are still obtainable.
>
> Any insights into this?
>
> Steve Wedge, W1ES
>
> Time flies like an arrow. Fruit flies like a banana.
>
> Sent from [Proton Mail](https://proton.me/mail/home) for iOS
>
>
>
>
|
On Sun, Jan 19, 2025 at 03:41 PM, Jim Shorney wrote:
>Interesting video but his glitch diode configuration has me puzzled. He complains (rightly so) that the B- was returned to the chassis but connects a reversed diode pair in which one of the diodes returns the B- to the >chassis? The glitch diode implementations I have seen use only a reverse biased diode from B- to chassis ground. Am I missing something?
With the 2nd diode installed (rvs connected pair).....the pair? ensures the B-? ?can't wander more than? +/-? .7 vdc? ?from chassis potential.? ?In the old days, something like a 10 ohm resistor from B- to chassis? would accomplish the same thing.? The concept in both cases was to float the B- from chassis potential just enough..... to be able to measure plate and grid current.? The issue with the 10 ohm resistor is if the anode arcs to the grid, or chassis, the fault current path is up from the chassis, through the resistor.... and back to the B- of the filter caps..... completing the loop.....and of course the resistor grenades.? With any anode to grid arc, or B+ to chassis arc, only one diode is required ( UN-banded end? facing the chassis).? ?I install the 2nd diode just to ensure the B-? can never wander more than +/- .7 vdc from the chassis. With any GG amp that has a grid over current circuit in it, it will not function correctly, since the 2nd diode is electrically in parallel with the? typ small value resistor used in the grid over current assy.... ( typ wired in series with the negative end of grid meter / grid shunt..... and chassis).? ?The V drop across the low value resistor is now in parallel with the 2nd diode, biasing the 2nd diode on.? Then grid current flows? up from the chassis....and through the 2nd diode........ instead of up through from the chassis.... and through the small value grid sense resistor...... which results in low or no? grid current readings, even though plate current reads normal, and PO is normal.?? That's why only one diode is used on ameritron amps that have the grid over current scheme installed.? ?In older books, you will see the rvs connected pair of diodes across? both the grid and plate current meter..... and that scheme still works......? ?with or without the grid overcurrent sense circuit installed.? In the L4B in question, the customer paid for packing and shipping to Ron, plus a helluva lot of money up front, only to be told it was unrepairable...and Ron wanted to keep the amp? and the HV supply....and the money.? Customer was told when the plate xfmr heats up, it shorts out.? Nothing wrong with the plate xfmr.? It's all fixed now.....plus the customer got his money back from Ron.? ? Dunno, but Ron might be starting to lose it.? ?And that could result in a dangerous scenario, esp with +2650vdc? involved.?
|
Ronnie Hull - W5SUM
David
Jim Shorney
Jay W6CJ