I'd say at least 600W.? In practise, it could be more because the power supply is likely a little "beefier" in proportion.
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Tuesday, March 5th, 2024 at 10:54 AM, mike bryce <prosolar@...> wrote:
Okay, with all this chatting about RF output for the L7
what should I see into a 50¦¸ load from my L75? It had but one 3-500Z.
Mike wb8vge
On Mar 5, 2024, at 10:01 AM, Steve Wedge, W1ES/4 via < w1es@...> wrote:
Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.
Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
|
Re: Drake L7 Power output
I have read that the power switches on the R4 series
transmitters and receivers are also hard to find and/or expensive. If so, is
there any benefit to installing some type of surge current reduction on these
units to extend their life, or is the failure mechanism mostly a mechanical
issue?
Bill N0CU
On Tue, Mar 5, 2024 at 11:58?AM Rick W4XA < myr748@...> wrote: On Tue, Mar 5, 2024 at 03:50 AM, Jim Altman wrote:
I was seeing a little arcing from the power switch contacts and installed the SSR with perfect results.? I could tell there was a little arc because the lightning detector on my weather station, only a few feet from the amp, would give me a false positive everytime i turned on the amp. Given the difficulty of finding replacement switches and rebuild kits for the switch, its a nice solution,
73 Jim, W4UCK
Yeah, you only see that "arc" if the switch is closed (or opened) while the voltage is at a peak (sine wave peak)
If you have ever plugged (or unplugged) in any device that's "ON" when you plug it in and have noticed a little spark, flipped a light switch on or off and heard the faint "snap" it likely happened at or near the sine wave peak (positive or negative) and of course,? you do not see that spark or hear it every time.
The trick is to "flip" the switch when the voltage is crossing at or near zero.?
Now maybe there are people that can "see" the sine wave in their heads and are fast enough to flip the switch at the right time,?? and won't need a little additional help getting the timing right.
For the rest of us, an SSR does it nicely.
W8ZR suggested using only one but you can use 2 when powering with 240AC.? (have a look at the )? page 16
You also do not have to use the DC controlled model either.? (Commander 2500 uses AC SSR's)? I am going to use the AC controlled model eliminating the need for a separate (always powered) small DC power supply? Either way, the control "side" of the SSR draws so little current as to be insignificant.
I'll be operating my Loudenboomer (powered by the L-4B plate transformer) on 120AC and always in the "high-voltage" mode. (240 is really not required for a 1kw input amp)? so I'll use one? OPTO22 Model 120A25 in the"hot" side.
For a 240 VAC powered amp, I would use two 240A45 (AC controlled) or? 240D45 (DC controlled) units.
See the link below for specs:?
The key with these is that? they "turn-on" at zero crossing (zero voltage) and give a slight measure of ramp-up in voltage.
I seem to remember that Tom, W8JI said the only reason "step-start" is needed, is to protect the ON/OFF switch.? with an SSR, the voltage on the PS circuits doesn't "slam" on it ramps up at a "sine-wave rate".? The actual current in the SSR control circuit is on the order of mA.
See page 2 of the above publication for the features.
I'm also using a CRYDOM MPDCD3 DC SSR for a keying interface to use with my IC-705 (similar to the OPTO22 DC60MP)? with a double 3v lithium battery holder for complete isolation to protect the IC-705 keying circuit? driving any amplifier.
All the SSR's I have bought so far I have gotten from eBay.? All used.? If you buy them new, they're crazy expensive but there's nothing wrong with used ones.? They either work or they don't.
BE VERY Careful buying the cheap knock-off SSR's.? They frequently have triacs inside that are not rated for the claimed current on the outside of the device.? And if you're going to run them at or near max current ratings, ABSOLUTELY MIND THE HEAT DISSIPATION!!
I'm using a 120V 25A device on my Loudenboomer and will use two 240v 45A devices in my L-4B (The L-4B even at Key-DOWN 1200 W output doesn't pop a 15A breaker.? Mounting to the chassis will likely be more than enough heat sink in the L-4B
Even after many hours the one I mounted in my AC-4 gets only slightly warm using the chassis as a heat sink (I used a little heat grease too)
I do have a small heat sink that I'll probably use in the Loudenboomer.
--
73/Rick
W4XA
*Every post is created using Linux
|
Re: Drake L7 Power output
I've run my amps at a kilowatt out on CW (with SSB plate voltage of course) with no issues. Digital modes, well, depends on your TX time. Short contest bursts you could probably do at 1 KW. They will tolerate FT8 at not more than 700 Watts, and in fact that is a good way of getting red in the plates of classic 3-500s to activate the getter material. Back in the pre-FT days I used to run JT65 at about the same level. W8JI has some great articles on amps at his web site, if you haven't been there yet. 73 -Jim NU0C On Tue, 5 Mar 2024 19:21:55 +0000 (UTC) "amfone via groups.io" <amfone20000@...> wrote: Thanks Jim for your input. I purchased my first L7 new in 1978, for years even on SSB I ran in the low voltage tune mode, only lately have I used the SSB mode when using that mode only, I always tune in the CW position or LV mode, then I will peak the amp as Drake notes using a watt meter.
I normally tune for about 500 watts on the meter, this is below of course the ratings for the tube noted by Drake in the manual. If I run AM phone with the amp using a modern rig I will have a carrier output of not more that 125 watts, running digital, mostly Olivia, when I use the amp I will run about 110 watts, all in the LV/CW position or position on the amp.
Running at the lower voltage will raise the grid current a little but you just need to keep an eye on it.
73 and thanks again.
Tim
WB8UHZ
On Tuesday, March 5, 2024 at 02:06:44 PM EST, Jim Shorney <jimnu0c@...> wrote:
No, NOT everyone is saying this. Always use CW mode when powering up and during initial tune up when changing bands. After that, do final tuning to the maximum power level that you expect to operate. Note that some advise to always tune up to the full 1200-ish watts output to mitigate possible "accidents" that can be damaging to the amp.
73
-Jim
NU0C
On Tue, 5 Mar 2024 14:29:15 +0000 (UTC)
"amfone via groups.io" <amfone20000@...> wrote:
? Let me? make sure I have this correct. I have two L7's and one L4B. Am I right that everyone is stating to tune these amps in the SSB position and just leave the amp in the SSB position all the time?
Also what about running digital modes I use the tune position for that but perhaps I should be using the SSB position. Please advise on both situations and many thanks.
73 Tim
WB8UHZ
? ? On Tuesday, March 5, 2024 at 08:19:02 AM EST, John K5MO <johnk5mo@...> wrote:?
?
? That is a particularly nice implementation. I'll do this when I get my L7 out of service.
Great writeup too.
John K5MO
?
-- 73 -Jim NU0C
|
Re: Drake L7 Power output
Thanks Jim for your input. I purchased my first L7 new in 1978, for years even on SSB I ran in the low voltage tune mode, only lately have I used the SSB mode when using that mode only, I always tune in the CW position or LV mode, then I will peak the amp as Drake notes using a watt meter.
I normally tune for about 500 watts on the meter, this is below of course the ratings for the tube noted by Drake in the manual. If I run AM phone with the amp using a modern rig I will have a carrier output of not more that 125 watts, running digital, mostly Olivia, when I use the amp I will run about 110 watts, all in the LV/CW position or position on the amp.
Running at the lower voltage will raise the grid current a little but you just need to keep an eye on it.
73 and thanks again.
Tim
WB8UHZ
On Tuesday, March 5, 2024 at 02:06:44 PM EST, Jim Shorney <jimnu0c@...> wrote:
No, NOT everyone is saying this. Always use CW mode when powering up and during initial tune up when changing bands. After that, do final tuning to the maximum power level that you expect to operate. Note that some advise to always tune up to the full 1200-ish watts output to mitigate possible "accidents" that can be damaging to the amp.
73
-Jim
NU0C
On Tue, 5 Mar 2024 14:29:15 +0000 (UTC) "amfone via groups.io" <amfone20000@...> wrote: >? Let me? make sure I have this correct. I have two L7's and one L4B. Am I right that everyone is stating to tune these amps in the SSB position and just leave the amp in the SSB position all the time? > > Also what about running digital modes I use the tune position for that but perhaps I should be using the SSB position. Please advise on both situations and many thanks. > 73 Tim > WB8UHZ > >? ? On Tuesday, March 5, 2024 at 08:19:02 AM EST, John K5MO < johnk5mo@...> wrote:? >? >? That is a particularly nice implementation. I'll do this when I get my L7 out of service. > Great writeup too. > John K5MO >? > > > > > -- 73 -Jim NU0C
|
Re: Drake L7 Power output
No, NOT everyone is saying this. Always use CW mode when powering up and during initial tune up when changing bands. After that, do final tuning to the maximum power level that you expect to operate. Note that some advise to always tune up to the full 1200-ish watts output to mitigate possible "accidents" that can be damaging to the amp. 73 -Jim NU0C On Tue, 5 Mar 2024 14:29:15 +0000 (UTC) "amfone via groups.io" <amfone20000@...> wrote: Let me? make sure I have this correct. I have two L7's and one L4B. Am I right that everyone is stating to tune these amps in the SSB position and just leave the amp in the SSB position all the time?
Also what about running digital modes I use the tune position for that but perhaps I should be using the SSB position. Please advise on both situations and many thanks.
73 Tim
WB8UHZ
On Tuesday, March 5, 2024 at 08:19:02 AM EST, John K5MO <johnk5mo@...> wrote:
That is a particularly nice implementation. I'll do this when I get my L7 out of service.
Great writeup too.
John K5MO
-- 73 -Jim NU0C
|
Re: Drake L7 Power output
On Tue, Mar 5, 2024 at 03:50 AM, Jim Altman wrote:
I was seeing a little arcing from the power switch contacts and installed the SSR with perfect results.? I could tell there was a little arc because the lightning detector on my weather station, only a few feet from the amp, would give me a false positive everytime i turned on the amp. Given the difficulty of finding replacement switches and rebuild kits for the switch, its a nice solution,
73 Jim, W4UCK
Yeah, you only see that "arc" if the switch is closed (or opened) while the voltage is at a peak (sine wave peak) If you have ever plugged (or unplugged) in any device that's "ON" when you plug it in and have noticed a little spark, flipped a light switch on or off and heard the faint "snap" it likely happened at or near the sine wave peak (positive or negative) and of course,? you do not see that spark or hear it every time. The trick is to "flip" the switch when the voltage is crossing at or near zero.? Now maybe there are people that can "see" the sine wave in their heads and are fast enough to flip the switch at the right time,?? and won't need a little additional help getting the timing right. For the rest of us, an SSR does it nicely. W8ZR suggested using only one but you can use 2 when powering with 240AC.? (have a look at the )? page 16 You also do not have to use the DC controlled model either.? (Commander 2500 uses AC SSR's)? I am going to use the AC controlled model eliminating the need for a separate (always powered) small DC power supply? Either way, the control "side" of the SSR draws so little current as to be insignificant. I'll be operating my Loudenboomer (powered by the L-4B plate transformer) on 120AC and always in the "high-voltage" mode. (240 is really not required for a 1kw input amp)? so I'll use one? OPTO22 Model 120A25 in the"hot" side. For a 240 VAC powered amp, I would use two 240A45 (AC controlled) or? 240D45 (DC controlled) units. See the link below for specs:?
The key with these is that? they "turn-on" at zero crossing (zero voltage) and give a slight measure of ramp-up in voltage.
I seem to remember that Tom, W8JI said the only reason "step-start" is needed, is to protect the ON/OFF switch.? with an SSR, the voltage on the PS circuits doesn't "slam" on it ramps up at a "sine-wave rate".? The actual current in the SSR control circuit is on the order of mA.
See page 2 of the above publication for the features. I'm also using a CRYDOM MPDCD3 DC SSR for a keying interface to use with my IC-705 (similar to the OPTO22 DC60MP)? with a double 3v lithium battery holder for complete isolation to protect the IC-705 keying circuit? driving any amplifier. All the SSR's I have bought so far I have gotten from eBay.? All used.? If you buy them new, they're crazy expensive but there's nothing wrong with used ones.? They either work or they don't. BE VERY Careful buying the cheap knock-off SSR's.? They frequently have triacs inside that are not rated for the claimed current on the outside of the device.? And if you're going to run them at or near max current ratings, ABSOLUTELY MIND THE HEAT DISSIPATION!! I'm using a 120V 25A device on my Loudenboomer and will use two 240v 45A devices in my L-4B (The L-4B even at Key-DOWN 1200 W output doesn't pop a 15A breaker.? Mounting to the chassis will likely be more than enough heat sink in the L-4B Even after many hours the one I mounted in my AC-4 gets only slightly warm using the chassis as a heat sink (I used a little heat grease too) I do have a small heat sink that I'll probably use in the Loudenboomer. --
73/Rick
W4XA
*Every post is created using Linux
|
Re: RV-75 only decrements
That frequency is the default setting for the RV7 5 to come up on. ??J107 gives you a few choices for the default power on frequency.? This is covered on Page 2-2 of the manual. ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of K6OXN Bob
Sent: Tuesday, March 05, 2024 12:21 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] RV-75 only decrements ? I got the replacement Optical Interrupters and replaced them in the RV-75. Made all the adjustments and checked the connections. This corrected the problem and the RV-75 now works as it should. Only problem I see is that the Power on Freq. is xx250.1. I can't find the adjustment for this in the manual. I take it as ok since 100hz is not that bad. All VCO and everything else is good and right on. 9vdc reads 8.994vdc on my fluke, and 5vdc reads 5.003 on the fluke. Thats good for government work as I see it. There is no adjustments that I can find.? Thanks everyone for all the help provided. I now have an RV-75 that works just fine.
73? Bob
|
Re: RV-75 only decrements
I got the replacement Optical Interrupters and replaced them in the RV-75. Made all the adjustments and checked the connections. This corrected the problem and the RV-75 now works as it should. Only problem I see is that the Power on Freq. is xx250.1. I can't find the adjustment for this in the manual. I take it as ok since 100hz is not that bad. All VCO and everything else is good and right on. 9vdc reads 8.994vdc on my fluke, and 5vdc reads 5.003 on the fluke. Thats good for government work as I see it. There is no adjustments that I can find.? Thanks everyone for all the help provided. I now have an RV-75 that works just fine.
73? Bob
|
Re: Drake MN7 Tuner Knobs
Just wanted to add. That is a great source! And they do not rape you on shipping! KUDOS!
Thanks again!
|
Re: Drake MN7 Tuner Knobs
Thanks Greg,
Appreciate it.
73
Bill
W4WCS
|
Okay, with all this chatting about RF output for the L7
what should I see into a 50¦¸ load from my L75? It had but one 3-500Z.
Mike wb8vge
toggle quoted message
Show quoted text
On Mar 5, 2024, at 10:01 AM, Steve Wedge, W1ES/4 via < w1es@...> wrote:
Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.
Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
|
Re: Drake L7 Power output
? Steve and Ralph thanks very much for the information, much appreciated.
Tim
On Tuesday, March 5, 2024 at 10:14:05 AM EST, Ralph Mowery via groups.io <ku4pt@...> wrote:
From what I have read the plate circuit will be slightly more efficient if you use the CW position if you only want to run around 500 or so watts instead of the full power.??
It is true that when the FCC went by input power the legal way was to tune up in the CW position to 1 kw input and then switch to SSB position if you wanted to run the amp to the 2 kw pep level.? Not needed now as the limit is 1500 watts output.
I use an external switch with a current limit resistor and relay for a 'soft start' and leave the amp switch on all the time.
?A while back there were several people putting out a rebuild kit for the power switch and I bought one but have not needed it.
Ralph ku4pt
On Tuesday, March 5, 2024 at 10:01:46 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.
Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
_,_
|
Re: Drake L7 Power output
From what I have read the plate circuit will be slightly more efficient if you use the CW position if you only want to run around 500 or so watts instead of the full power.??
It is true that when the FCC went by input power the legal way was to tune up in the CW position to 1 kw input and then switch to SSB position if you wanted to run the amp to the 2 kw pep level.? Not needed now as the limit is 1500 watts output.
I use an external switch with a current limit resistor and relay for a 'soft start' and leave the amp switch on all the time.
?A while back there were several people putting out a rebuild kit for the power switch and I bought one but have not needed it.
Ralph ku4pt
On Tuesday, March 5, 2024 at 10:01:46 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.
Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
_,_
|
Re: Drake L7 Power output
Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.
Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Mar 5, 2024 at 9:29 AM, amfone via groups.io < amfone20000@...> wrote:
Let me? make sure I have this correct. I have two L7's and one L4B. Am I right that everyone is stating to tune these amps in the SSB position and just leave the amp in the SSB position all the time?
Also what about running digital modes I use the tune position for that but perhaps I should be using the SSB position. Please advise on both situations and many thanks.
73 Tim
WB8UHZ
On Tuesday, March 5, 2024 at 08:19:02 AM EST, John K5MO <johnk5mo@...> wrote:
That is a particularly nice implementation. I'll do this when I get my L7 out of service.
Great writeup too.
John K5MO
|
HI Steve,
Well just before you wrote today's reply, I pulled 2x 12ba6's from my tr4c and put them in the r4b, it improved the symptom a little bit, but still the zero pot needs to be all to way to the endpoint still(shorted). Q4(2N3877) is 100% good I pulled the original transistor and it checked out just fine even though I tried to replace with a bc547 and as I suspected it made no change, so that's out of the way. Now I did managed to find 2x12ba6's within EU borders so they are in the mail floating somewhere, but I kinda doubt it's gassy tubes(just my gut feeling). It gotta be somewhere else as I really don't get why the Zero adjustment need to be cranked all the way to ~0 ohm position.. Somewhere a resistor gotta be seriously out of specs I guess.
But Thank you very much for all your input, I surely do appreciate, please let me know if some good ideas should pop up.
73's de oz8abr Michael.
?
On Tue, Mar 5, 2024 at 2:43?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Those are okay.
If you don¡¯t have extra tubes, try swapping around the 12BA6¡¯s and see if anything changes.? Also look at the AGC circuit and make sure that the transistor (can¡¯t remember if it¡¯s Q4 or Q7 but it¡¯s the one that generates the AGC voltage) is a 2N3877 or equivalent.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Mar 5, 2024 at 5:01 AM, Michael Jensen < kavigal@...> wrote: Okay they resistors measure as follows: Both liftet from PCB R41=837 OHMS R89=557 OHMS So not horrible out of tolerances I guess.
On Mon, Mar 4, 2024 at 11:43?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Those figures don't indicate a problem. Ideally, TP2, with the preselector detuned, should read -1.35V Your reading isn't terrible. So now we need to see why you're getting S5 with no signal. On the schematic, R41 and R89, in the meter bridge circuit, should be checked.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent with secure email.
On Monday, March 4th, 2024 at 3:53 PM, Michael Jensen < kavigal@...> wrote:
@Steve Tonight's numbers :).
Cold and detuned TP2=-1.335v
30 mins TP2=-1.267v
60 mins TP2=-1.259v
I get your point about "
The important part here is if the voltage at TP2 with respect to time."
Now what is the verdict? Too much voltage drop? What do you think?
Thanks, Michael.
On Sun, Mar 3, 2024 at 11:49?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Resistance is the most important here.
We now need to measure the TP2 voltage from startup to a point long after warmup. If this value drifts towards 0V then there is a chance that you have a gassy tube.
The important part here is if the voltage at TP2 with respect to time.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent with secure email.
On Sunday, March 3rd, 2024 at 12:50 PM, Michael Jensen < kavigal@...> wrote:
HI again!
Tak for linked Glenn, kunne godt minde lidt om mit problem :). Okay enough "Danglish" .. @Steve, Thanks for taking your time to reply! Detuned and with AVC ON, TP2 voltage is-1.26, right now, I did an adjustment cold, so seems to have dropped ever so slightly after proper warm up.
RF GAIN Pot measures ~12Ohms(seem to be some capacitance) with wires attached, so guess that is quite okay.
Thanks, Michael-oz8abr
On Sun, Mar 3, 2024 at 2:11?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Michael, what is the voltage at TP2? There are other resistors in the bridge circuit and I have seen them go out of tolerance.
What is the resistance reading across the RF GAIN pot?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Sun, Mar 3, 2024 at 07:09, Glenn, OZ1HFT < glenn.mh.dk@...> wrote: Hi Michael
See this thread:
/g/DRAKE-RADIO/topic/r_4b_agc_issues_part_trois/103544827
--
best regards,
Glenn, OZ1HFT
|
Re: Drake L7 Power output
Let me? make sure I have this correct. I have two L7's and one L4B. Am I right that everyone is stating to tune these amps in the SSB position and just leave the amp in the SSB position all the time?
Also what about running digital modes I use the tune position for that but perhaps I should be using the SSB position. Please advise on both situations and many thanks.
73 Tim
WB8UHZ
On Tuesday, March 5, 2024 at 08:19:02 AM EST, John K5MO <johnk5mo@...> wrote:
That is a particularly nice implementation. I'll do this when I get my L7 out of service.
Great writeup too.
John K5MO
|
Those are okay.
If you don¡¯t have extra tubes, try swapping around the 12BA6¡¯s and see if anything changes. ?Also look at the AGC circuit and make sure that the transistor (can¡¯t remember if it¡¯s Q4 or Q7 but it¡¯s the one that generates the AGC voltage) is a 2N3877 or equivalent.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Mar 5, 2024 at 5:01 AM, Michael Jensen < kavigal@...> wrote: Okay they resistors measure as follows: Both liftet from PCB R41=837 OHMS R89=557 OHMS So not horrible out of tolerances I guess.
On Mon, Mar 4, 2024 at 11:43?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Those figures don't indicate a problem. Ideally, TP2, with the preselector detuned, should read -1.35V Your reading isn't terrible. So now we need to see why you're getting S5 with no signal. On the schematic, R41 and R89, in the meter bridge circuit, should be checked.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent with secure email.
On Monday, March 4th, 2024 at 3:53 PM, Michael Jensen < kavigal@...> wrote:
@Steve Tonight's numbers :).
Cold and detuned TP2=-1.335v
30 mins TP2=-1.267v
60 mins TP2=-1.259v
I get your point about "
The important part here is if the voltage at TP2 with respect to time."
Now what is the verdict? Too much voltage drop? What do you think?
Thanks, Michael.
On Sun, Mar 3, 2024 at 11:49?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Resistance is the most important here.
We now need to measure the TP2 voltage from startup to a point long after warmup. If this value drifts towards 0V then there is a chance that you have a gassy tube.
The important part here is if the voltage at TP2 with respect to time.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent with secure email.
On Sunday, March 3rd, 2024 at 12:50 PM, Michael Jensen < kavigal@...> wrote:
HI again!
Tak for linked Glenn, kunne godt minde lidt om mit problem :). Okay enough "Danglish" .. @Steve, Thanks for taking your time to reply! Detuned and with AVC ON, TP2 voltage is-1.26, right now, I did an adjustment cold, so seems to have dropped ever so slightly after proper warm up.
RF GAIN Pot measures ~12Ohms(seem to be some capacitance) with wires attached, so guess that is quite okay.
Thanks, Michael-oz8abr
On Sun, Mar 3, 2024 at 2:11?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Michael, what is the voltage at TP2? There are other resistors in the bridge circuit and I have seen them go out of tolerance.
What is the resistance reading across the RF GAIN pot?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Sun, Mar 3, 2024 at 07:09, Glenn, OZ1HFT < glenn.mh.dk@...> wrote: Hi Michael
See this thread:
/g/DRAKE-RADIO/topic/r_4b_agc_issues_part_trois/103544827
--
best regards,
Glenn, OZ1HFT
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Re: Drake MN7 Tuner Knobs
$5.95 for 2 inch knob, 1/16¡± set screw  
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Re: Drake L7 Power output
That is a particularly nice implementation. I'll do this when I get my L7 out of service.
Great writeup too.
John K5MO
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Re: Mechanical Zero of TR-4C S-Meter
When the set is powered up, you should be able to see it go to S1 with no signal.?
Unlike the meters in the Twins, these meters do have a mechanical zero setting BUT you will need to remove it from the panel and remove the cover. I don¡¯t like doing this because it seems that ANY messing with these meters can turn them into ¡°bouncers¡±.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Mon, Mar 4, 2024 at 22:26, Gary Follett < xntrick1948@...> wrote: That S meter is so close to useless that it simply does not matter where it rests at zero signal. It simply tells you, ¡°This guy is loud¡± and ¡°That guy is not loud¡±.
Gary
W0DVN
> On Mar 4, 2024, at 9:19?PM, Lyndon VE7TFX <lyndon@...> wrote:
>
> Michael Smith via groups.io writes:
>
>> In pre-alignment stage, I have a TR-4C with the S-meter indicating 1.5, wit=
>> h power off and chassis in the normal horizontal position. =C2=A0Is mechani=
>> cally zeroing the S-meter possible, and it is necessary? =C2=A0I=E2=80=99ve=
>> applied a little rotational torque to the chassis to verify the S-meter ne=
>> edle is free to move.
>
> Static buildup? Try rubbing the meter face with a "no cling"
> dryer sheet.
>
> --lyndon
>
>
>
>
>
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Jim Shorney
Bill
Greg W9GB