Re: Drake TR7 transmit limit on digital modes
I have two TR7's with their companion PS7 supplies and concur that having
fans on both the power supply and the TR7 is the best way to go. Use of the
FA7 greatly improves the frequency stability of the TR7 and prolongs the
life of the PA transistors. However, I disagree with any fan that fits is
OK. The FA7 is a Rotron Sprite SU2C1 (19 CFM) fan that was private labeled
for Drake. Power transistors are sensitive to temperature changes and
engineers design circuits to run in within a specific temperature band for
optimal performance. Too cool, while not as bad as too hot, is still not a
desired result. The heatsink in the TR7 is a patented design that relies on
the amount of air movement delivered by the FA7 to keep things within the
desired temperature band. Except on rare occasions, I let my TR7's come up
to ambient temperature before I get on the air with them.
FYI, while the FA7 tends to be a bit pricy when you can find a good one, the
Rotron SUC21 is readily available brand new for less than half the cost.
All you have to do to a stock Rotron fan is put a two prong AC plug on it.
You can easily adapt a polarized plug to fit the receptacle on the TR7 and
PS7. The only thing you might want to add to is a finger guard, which is
also not too hard to find.
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Jim Shorney Sent: Tuesday, April 23, 2024 6:32 PM To: [email protected]Subject: Re: [DRAKE-RADIO] Drake TR7 transmit limit on digital modes I would say that you want both fans even if you don't run digital modes. The fan on the PS cools the main filter caps which will extend their life. The fan on the radio keeps the internal temperature more stable across T/R cycles which reduces drift, as well as extending component life in the PA. Any off the shelf 20CFM fan of the proper form factor, oriented to pull air OUT, will work. You don't need a gen-yoo-wine FA7. 73 -Jim NU0C On Tue, 23 Apr 2024 18:20:37 -0400 "Omni via groups.io" <selcor@...> wrote: The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If you have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which place similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with a PS7 you should also have a FA7 on the supply for digital modes. --- This email has been checked for viruses by AVG.
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Re: L7 makes alot of smoke
Long ago, I can remember fixing an SB-220 that would get a plate-to-grid short, ONLY upon heating up.? It would immediately fry the grid RFC.? Cool the tube down, no short.
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Tuesday, April 23rd, 2024 at 6:40 PM, K6OXN Bob <bobk6oxn@...> wrote:
I have completely scanned the Plate Tune Cap and can find no bent or arcing on the plates. I have my original set of 3-500z and will use them to make sure these 3-500zg are ok. I checked the tubes and no problems in ohm readings. I also have a new matched set of 3-500zg's from RF parts, but don't want to try them yet because of this problem.
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Re: L7 makes alot of smoke
I recently had a Chinese 3-500zg flash over in a L7. It wasn't pretty. 73 -Jim NU0C On Tue, 23 Apr 2024 15:40:47 -0700 "K6OXN Bob via groups.io" <bobk6oxn@...> wrote: I have completely scanned the Plate Tune Cap and can find no bent or arcing on the plates. I have my original set of 3-500z and will use them to make sure these 3-500zg are ok. I checked the tubes and no problems in ohm readings. I also have a new matched set of 3-500zg's from RF parts, but don't want to try them yet because of this problem.
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Re: L7 makes alot of smoke
I have completely scanned the Plate Tune Cap and can find no bent or arcing on the plates. I have my original set of 3-500z and will use them to make sure these 3-500zg are ok. I checked the tubes and no problems in ohm readings. I also have a new matched set of 3-500zg's from RF parts, but don't want to try them yet because of this problem.
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Re: L7 makes alot of smoke
Bob, your exciter is a TR7 on 40M, correct? I wonder if the nasty "40M oscillation" that has been batted around here may be in play at this juncture.?
After you get the amp back to an operational condition, I would try a different radio even if you have to borrow one. Make sure any other rig especially?solid state,?can either handle the voltage and current of the L7 or use an interface. I mentioned this as I am not familiar with the keying arrangement of the L7.
Bob K9JU
On Tuesday, April 23, 2024 at 06:21:22 PM EDT, Jim Shorney <jimnu0c@...> wrote:
The tubes may have been gassy. That can happen if they are babied. You might have been able to recondition them by running them for a while at low voltage with some red in the plates. They need to get that hot for the getter materiel to scavenge the gas. That's why they can fail early if they have been babied.
73
-Jim
NU0C
On Tue, 23 Apr 2024 22:06:45 +0000 (UTC) "amfone via groups.io" <amfone20000@...> wrote: >? Wish you had another pair of 3-500Z tubes to put in. I had that problem with what looked like a new set of Eimac tubes, the red ink was perfect, the guy that sold them to me said he had just used them. I checked them with an ohm meter, no issue. I put them in the amp(L7) and in low power no issues in high power lighting struck fuse resistor fried. I took the tubes out of course and put in my old tubes and all was OK. The seller did after I found him refund my money. > > 73 Tim > WB8UHZ
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Re: Drake TR7 transmit limit on digital modes
I would say that you want both fans even if you don't run digital modes. The fan on the PS cools the main filter caps which will extend their life. The fan on the radio keeps the internal temperature more stable across T/R cycles which reduces drift, as well as extending component life in the PA. Any off the shelf 20CFM fan of the proper form factor, oriented to pull air OUT, will work. You don't need a gen-yoo-wine FA7. 73 -Jim NU0C On Tue, 23 Apr 2024 18:20:37 -0400 "Omni via groups.io" <selcor@...> wrote: The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If you
have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which place
similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with a
PS7 you should also have a FA7 on the supply for digital modes.
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Re: L7 makes alot of smoke
The tubes may have been gassy. That can happen if they are babied. You might have been able to recondition them by running them for a while at low voltage with some red in the plates. They need to get that hot for the getter materiel to scavenge the gas. That's why they can fail early if they have been babied. 73 -Jim NU0C On Tue, 23 Apr 2024 22:06:45 +0000 (UTC) "amfone via groups.io" <amfone20000@...> wrote: Wish you had another pair of 3-500Z tubes to put in. I had that problem with what looked like a new set of Eimac tubes, the red ink was perfect, the guy that sold them to me said he had just used them. I checked them with an ohm meter, no issue. I put them in the amp(L7) and in low power no issues in high power lighting struck fuse resistor fried. I took the tubes out of course and put in my old tubes and all was OK. The seller did after I found him refund my money.
73 Tim
WB8UHZ
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Re: Drake TR7 transmit limit on digital modes
The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If you
have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which place
similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with a
PS7 you should also have a FA7 on the supply for digital modes.
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Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Tim W1TM via groups.io Sent: Tuesday, April 23, 2024 5:11 PM To: [email protected]Subject: [DRAKE-RADIO] Drake TR7 transmit limit on digital modes The Drake TR7 has beer great rig for me. I had an old Kantronics KAM XL I wanted to interface with its but decide to go back to the future and something like what was available when the sig was made. I found a little VT100 terminal emulator on eBay and added a vintage keyboard and a VGA monitor. Now I can use the tnc directly by typing in commands. So for I have managed to make contacts on PSK31 and RTTY including one to Honduras. Before I continue to work these modes I need to the digital power limits for the rig. My manual mentions that there are none if you have the for that my rig has. I am skeptical about this. What should I power to limit my power to? Tim Gordish W1TM TR7 #6925 --- This email has been checked for viruses by AVG.
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Re: L7 makes alot of smoke
Check the plate tune capacitor for any signs of arcing. Also check you coax and antenna system. A load mismatch can cause unpleasant things. 73 -Jim NU0C On Tue, 23 Apr 2024 14:54:29 -0700 "K6OXN Bob via groups.io" <bobk6oxn@...> wrote: The power supply has the Harbach mod done and has been working great. Of course when this happens only the .82 fuse resistor blows. I do notice some possible arc points on the cover of the L7 and will place some Fish paper in that area.? After the first repair, I left the amp on in idle with HV at 2700+ and had no problems for over 4 hours in that state. Now it seems that the arcing is taking out the 47 ohm parasitic resistors when I am modulating in SSB.? Only tested on 40 meters at this time and cannot see any parasitic oscillations on the scope. Replacing the parasitic resistors now along with the .82 in the PS.? Will bring it up slowly and may try SSB with the amp in CW mode unless that is not recommended. Otherwise, I will reduce the TR7 to about 50 watts and see how it is doing.
73? Bob
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Re: Drake TR7 transmit limit on digital modes
Do you have the optional fan on the TR7? If so there is no limit for all practical purposes. I have been running my TR7s at full output on JT/FT modes for years and they don't even break a sweat. If you don't have the fan, get one. :) 73 -Jim NU0C On Tue, 23 Apr 2024 16:10:39 -0500 "Tim W1TM via groups.io" <gordisht@...> wrote: The Drake TR7 has beer great rig for me. I had an old Kantronics KAM XL I wanted to interface with its but decide to go back to the future and something like what was available when the sig was made. I found a little VT100 terminal emulator on eBay and added a vintage keyboard and a VGA monitor. Now I can use the tnc directly by typing in commands. So for I have managed to make contacts on PSK31 and RTTY including one to Honduras.
Before I continue to work these modes I need to the digital power limits for the rig. My manual mentions that there are none if you have the for that my rig has. I am skeptical about this. What should I power to limit my power to?
Tim Gordish
W1TM
TR7 #6925
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Re: L7 makes alot of smoke
Wish you had another pair of 3-500Z tubes to put in. I had that problem with what looked like a new set of Eimac tubes, the red ink was perfect, the guy that sold them to me said he had just used them. I checked them with an ohm meter, no issue. I put them in the amp(L7) and in low power no issues in high power lighting struck fuse resistor fried. I took the tubes out of course and put in my old tubes and all was OK. The seller did after I found him refund my money.
73 Tim
WB8UHZ
On Tuesday, April 23, 2024 at 05:54:31 PM EDT, K6OXN Bob <bobk6oxn@...> wrote:
The power supply has the Harbach mod done and has been working great. Of course when this happens only the .82 fuse resistor blows. I do notice some possible arc points on the cover of the L7 and will place some Fish paper in that area.? After the first repair, I left the amp on in idle with HV at 2700+ and had no problems for over 4 hours in that state. Now it seems that the arcing is taking out the 47 ohm parasitic resistors when I am modulating in SSB.? Only tested on 40 meters at this time and cannot see any parasitic oscillations on the scope. Replacing the parasitic resistors now along with the .82 in the PS.? Will bring it up slowly and may try SSB with the amp in CW mode unless that is not recommended. Otherwise, I will reduce the TR7 to about 50 watts and see how it is doing.
73? Bob
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Re: L7 makes alot of smoke
The power supply has the Harbach mod done and has been working great. Of course when this happens only the .82 fuse resistor blows. I do notice some possible arc points on the cover of the L7 and will place some Fish paper in that area.? After the first repair, I left the amp on in idle with HV at 2700+ and had no problems for over 4 hours in that state. Now it seems that the arcing is taking out the 47 ohm parasitic resistors when I am modulating in SSB.? Only tested on 40 meters at this time and cannot see any parasitic oscillations on the scope. Replacing the parasitic resistors now along with the .82 in the PS.? Will bring it up slowly and may try SSB with the amp in CW mode unless that is not recommended. Otherwise, I will reduce the TR7 to about 50 watts and see how it is doing.
73? Bob
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Re: L-4PS Plate transformer primary color coding
I sent an email to Ron and he replied VERY quickly and indicated he would correct his picture........
I also looked at the (uploaded)? BAMA L-7 manual and it has the colors depicted correctly!
It appears that in all of the "pictures" that the colors depicted on the schematics are "penciled-in" by someone other than Drake (they appear hand printed)
It also has me wondering if the picture depicted on Rons site was originally correct ...... and maybe Drake might have changed transformer supplier in mid stream and they came with those BRN--BRN/BLK wires reversed ....and then of course, Drake never bothered to tell anyone!!
Who knows?
Sometimes these old radios can be so frustrating when the schematics are NOT exactly correct!!
--
73/Rick
W4XA
*Every post is created using Linux
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Re: L7 makes alot of smoke
Will the L7 do this when just in Idle no transmit? ? Has the power supply been rebuilt ever?
Tim
WB8UHZ
On Tuesday, April 23, 2024 at 03:31:13 PM EDT, K6OXN Bob <bobk6oxn@...> wrote:
[Edited Message Follows]
Well thought I had it fixed but again without any notice, large spark and bang.? Lost the .82 in the power supply and I suspect the 47 ohm parasitic resistors in the Amp.? I was using 47 ohm 2 watt carbon resistors in the parasitic choke, should I change them for something else?? When they go they were blackened and fractured. I am open to any suggestions. It happened when I was talking on 40 meters for about 45 seconds, operating at about 750 watts out.? Did not hear an arc.? Will be examining it more better this time. Will have to get some more 47 ohm resistors.? I am beyond my capabilities this time.? Any help or suggestions are welcome.
73? Bob
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Re: L-4PS Plate transformer primary color coding
Found it!
I sent Ron an email informing him of the typo.
This has me wondering if Drake originally used transformers with this primary color convention and changed it mid-stream and the memo is buried in history!!.........
--
73/Rick
W4XA
*Every post is created using Linux
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Drake TR7 transmit limit on digital modes
The Drake TR7 has beer great rig for me. I had an old Kantronics KAM XL I wanted to interface with its but decide to go back to the future and something like what was available when the sig was made. I found a little VT100 terminal emulator on eBay and added a vintage keyboard and a VGA monitor. Now I can use the tnc directly by typing in commands. So for I have managed to make contacts on PSK31 and RTTY including one to Honduras.
Before I continue to work these modes I need to the digital power limits for the rig. My manual mentions that there are none if you have the for that my rig has. I am skeptical about this. What should I power to limit my power to?
Tim Gordish
W1TM
TR7 #6925
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All bands.
I like the idea of putting the Tiny SA nearby to see if it "sees" anything else going on.
I'm going to print these responses and put them on top of the rig so that I remember them when I remove the cover.? Right now, I have a T-4XB on the bench that's making me pull out my hair.? Carrier oscillator won't oscillate.? the grid and cathode voltages are off but not by a lot.? I have a known-good T-4XB next to it and I'm comparing resistances and voltages.? I'm finding issues with resistances at the GAIN control.? The pots are good but something else is happening there.? I never realised that the amplitude of the CO changed with the GAIN setting.? This all goes through a very manky-looking FUNCTION switch...
More later...
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Tuesday, April 23rd, 2024 at 1:35 PM, Bob Loving <bob.loving@...> wrote:
Steve, is this action noted on all bands? Or only one, namely 40M?
The oscillation on 40M occurs up in the 9- to 10-MHz range so the TX LPF may attenuate the signal sufficiently to not indicate on a Wattmeter. Use a spectrum analyzer to "sniff" with a loop in the LPF section while this is happening.?
SAs aren't as expensive as in the old days. Even the "Tinysa Spectrum Analyzer" is available for $60-$70 on Amazon and will do your cooking proud.
73, Bob K9JU
Maryville, TN
On Tuesday, April 23, 2024 at 12:30:53 PM EDT, Jim Shorney <jimnu0c@...> wrote:
Find out where the meter spike voltage is coming from. If it is from the wattmeter sensor you may have a parasitic oscillation. If it is coming from the 2nd IF/Audio board there may be a timing issue. Which version board do you have? If it is a real TR7A you should have version 2, which has all the fixes. But with board swapping and "A" version fakery you never know for sure unless you look. The version 1 IF/Audio board had some problems that were fixed by factory mods. Very old boards in the field may not have all of the mods. Check the values of R1186 and R1187. The schematics say 10K but I have seen values as low as 1.5K in the real world. Lower values will reduce the T/R turnaround time. You might also check C1151.
How does your CW look? The CW generator is a crystal circuit on the IF/Audio board. It is a bit finicky to get right as Floyd K8AC found out. See his article about TR7 key clicks on HFN.
The VOX and T/R control magic happen on the TX Exciter board. You may want to check for marginal electrolytics there. Also check the +10T and +10R for proper switching. It should be a reasonably fast transition between +10 and zero.
73
-Jim
NU0C
On Tue, 23 Apr 2024 13:40:58 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
> Whilst we are in discussions over wattmeter readings and so on, I¡¯ve had a chronic anomaly with my TR7A and its wattmeter in CW mode.
>
> When I transmit on CW, upon release of the key, the meter swings to the right peg. Then we have normal readings. During the time that the meter indicates maximum, there is no RF at the antenna connection (verified with external wattmeter and with a scope).
>
> This happens only in CW, with the VOX delay set to minimum or near minimum. If I bring the delay out to around 1 second, everything looks normal. It occurs on all bands. There¡¯s no indication in SSB or AM.
>
> Could I be looking at a sticky relay? I don¡¯t have a spare to swap, at the moment.
>
> 73,
>
> Steve Wedge, W1ES/4
>
> Time flies like an arrow. Fruit flies like a banana.
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Re: L7 makes alot of smoke
Well thought I had it fixed but again without any notice, large spark and bang.? Lost the .82 in the power supply and I suspect the 47 ohm parasitic resistors in the Amp.? I was using 47 ohm 2 watt carbon resistors in the parasitic choke, should I change them for something else?? When they go they were blackened and fractured. I am open to any suggestions. It happened when I was talking on 40 meters for about 45 seconds, operating at about 750 watts out.? Did not hear an arc.? Will be examining it more better this time. Will have to get some more 47 ohm resistors.? I am beyond my capabilities this time.? Any help or suggestions are welcome.
73? Bob
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You will get more interest if you list installed options. IF filters, noise blanker, AUX7, fans? 73 -Jim NU0C On Tue, 23 Apr 2024 13:43:12 -0500 "Robin K4IDC via groups.io" <RobinK4IDC@...> wrote: One owner TR7 station available in Nashville, TN. $1500 for all of it, will
ship with insurance at buyer's expense, not interested in trades, serious
offers seriously considered. All the items work properly; only possible
exception would possibly be the phone patch as it hasn't been utilized in
quite a number of years. Please contact me directly with any questions; I'm
good on QRZ.
TR7 transceiver (model 1337), just back from service by Ron Baker WB4HFN;
details attached
MS7 speaker
RV7 remote VFO
PS7 power supply
P75 phone patch
Also included are the original boxes for the TR7 & the PS7, a small parts
cabinet with extender cards & other Drake bits & pieces.
Photos here:
Thanks,
Robin Midgett K4IDC
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Bob makes a good point. Indeed this was my first thought. However in my experience the 40m oscillation is a sustained event. The fact that the meter spike disappears when the VOX delay is set longer suggests to me that something else is going on. Key question: does it do it into a dummy load as well? The 40m oscillation *usually* only appears with a reactive load. I say usually because I had one that was so bad I was able to make it oscillate into a dummy, and also on 17m. If you haven't yet, you need to buy a TinySA or TinySA Ultra. I have one of each. Fine toys, er, tools. Be sure to check the Wiki and buy from an approved seller. Bad clones abound. R&L in the USA is a good bet. DON'T buy from Amazon! 73 -Jim NU0C On Tue, 23 Apr 2024 17:35:45 +0000 (UTC) "Bob Loving via groups.io" <bob.loving@...> wrote: Steve, is this action noted on all bands? Or only one, namely 40M?
The oscillation on 40M occurs up in the 9- to 10-MHz range so the TX LPF may attenuate the signal sufficiently to not indicate on a Wattmeter. Use a spectrum analyzer to "sniff" with a loop in the LPF section while this is happening.?
SAs aren't as expensive as in the old days. Even the "Tinysa Spectrum Analyzer" is available for $60-$70 on Amazon and will do your cooking proud.
73,Bob K9JU
Maryville, TN
On Tuesday, April 23, 2024 at 12:30:53 PM EDT, Jim Shorney <jimnu0c@...> wrote:
Find out where the meter spike voltage is coming from. If it is from the wattmeter sensor you may have a parasitic oscillation. If it is coming from the 2nd IF/Audio board there may be a timing issue. Which version board do you have? If it is a real TR7A you should have version 2, which has all the fixes. But with board swapping and "A" version fakery you never know for sure unless you look. The version 1 IF/Audio board had some problems that were fixed by factory mods. Very old boards in the field may not have all of the mods. Check the values of R1186 and R1187. The schematics say 10K but I have seen values as low as 1.5K in the real world. Lower values will reduce the T/R turnaround time. You might also check C1151.
How does your CW look? The CW generator is a crystal circuit on the IF/Audio board. It is a bit finicky to get right as Floyd K8AC found out. See his article about TR7 key clicks on HFN.
The VOX and T/R control magic happen on the TX Exciter board. You may want to check for marginal electrolytics there. Also check the +10T and +10R for proper switching. It should be a reasonably fast transition between +10 and zero.
73
-Jim
NU0C
On Tue, 23 Apr 2024 13:40:58 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
Whilst we are in discussions over wattmeter readings and so on, I¡¯ve had a chronic anomaly with my TR7A and its wattmeter in CW mode.
When I transmit on CW, upon release of the key, the meter swings to the right peg. Then we have normal readings. During the time that the meter indicates maximum, there is no RF at the antenna connection (verified with external wattmeter and with a scope).
This happens only in CW, with the VOX delay set to minimum or near minimum. If I bring the delay out to around 1 second, everything looks normal. It occurs on all bands. There¡¯s no indication in SSB or AM.
Could I be looking at a sticky relay? I don¡¯t have a spare to swap, at the moment.
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
-- 73 -Jim NU0C
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Jim Shorney
