7000 intermittent?


wabate
 

Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


david vanhorn
 

"Fire and glass"?



On Tue, Jun 1, 2021, 9:53 AM wabate via groups.io <wabate=verizon.net@groups.io> wrote:
Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


Pasquale S
 

Hi Bill

 

SWR sensing circuitry is the same between HF and 50 MHz.

 

Regards

 

Pasquale IW0HEX

 

 

Inviato da Posta per Windows 10

 

Da: wabate via groups.io
Inviato: martedì 1 giugno 2021 17:53
A: ic7000@groups.io
Oggetto: [ic7000] 7000 intermittent?

 

Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB

 


Kurt Sweeny
 

Wow ! Interesting problem, can’t wait to hear the diagnosis.

 

Some thoughts:

  1. The antenna system has the possibility of becoming a  dynamic load (low probability), not so for a dummy load in working order.
  2. Doesn’t 6M share some / a lot of transmission circuitry with HF (same so-239) ?
  3. If the answer to b is yes and 1-30Mhz is OK, could this be a component failure that only occurs above a certain frequency.
  4. The problem is intermittent. What components can fail and briefly recover?

 

Kurt

KD6LZV

 

From: ic7000@groups.io <ic7000@groups.io> On Behalf Of david vanhorn
Sent: Tuesday, June 1, 2021 9:40 AM
To: ic7000@groups.io
Subject: Re: [ic7000] 7000 intermittent?

 

"Fire and glass"?

 

 

 

On Tue, Jun 1, 2021, 9:53 AM wabate via groups.io <wabate=verizon.net@groups.io> wrote:

Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


david vanhorn
 

" Wow ! Interesting problem, can’t wait to hear the diagnosis."

I agree, this one is going to be interesting since it's misbehaving on the dummy load. 
My first suspect on any older electronics is always the electrolytic caps, but I can't think how that would cause this problem.  Still, if you have to open it up anyway...



On Tue, Jun 1, 2021 at 11:43 AM Kurt Sweeny <damele@...> wrote:

Wow ! Interesting problem, can’t wait to hear the diagnosis.

 

Some thoughts:

  1. The antenna system has the possibility of becoming a  dynamic load (low probability), not so for a dummy load in working order.
  2. Doesn’t 6M share some / a lot of transmission circuitry with HF (same so-239) ?
  3. If the answer to b is yes and 1-30Mhz is OK, could this be a component failure that only occurs above a certain frequency.
  4. The problem is intermittent. What components can fail and briefly recover?

 

Kurt

KD6LZV

 

From: ic7000@groups.io <ic7000@groups.io> On Behalf Of david vanhorn
Sent: Tuesday, June 1, 2021 9:40 AM
To: ic7000@groups.io
Subject: Re: [ic7000] 7000 intermittent?

 

"Fire and glass"?

 

 

 

On Tue, Jun 1, 2021, 9:53 AM wabate via groups.io <wabate=verizon.net@groups.io> wrote:

Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB



--
K1FZY (WA4TPW) SK  9/29/37-4/13/15


Max
 

I'd be curious as to the fix for this because I have a 7000 with a similar  problem. I never tried mine on 6M, but all the lower bands show a high SWR. But mine doesn't reduce the power out, it runs wide open putting out about 140 watts no matter the power setting is. My SWR meters and my NanoVNA shows my antennas and dummy load to be fine.

Max KG4PID

On Tuesday, June 1, 2021, 10:53:55 AM CDT, wabate via groups.io <wabate@...> wrote:


Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


Ludovic Ludo
 


Good evening,

I would rather think the SWR circuit is correct But then there is an intermittent cut.
Check the transmitter output socket first and solder on the PCB.


Best regards,
Ludovic - F5PBG
http://radioamateur.forumsactifs.com/f36-ic-7000


Le 01/06/2021 à 17:53, wabate via groups.io a écrit :

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Leroy Higgins
 

Bill, does your radio have a parasitic oscillation on 6M?

Using a 100 MHz oscilloscope, tape the 10:1 probe to your RF output coax and look at the waveform with the transmitter keyed.  Should be a nice clean sine wave of your transmit frequency.  If a parasitic is present the waveform won't be a clean sine wave.   Try this method using your antenna and the dummy load.  

The last time I used this method was on a 2 kW, CW, vacuum tube test transmitter with low RF output power at 15 MHz.   The oscilloscope on the coax method indicated the RF had 60 Hz modulation caused by a power supply filter failure, in the exciter.   When the 60 Hz modulation was eliminated the Bird watt meter read the correct power.

Most coax with stranded wire braid has enough RF leakage to monitor your transmit frequency and modulation.  You can't measure transmit power level accurately, with this method, but you can easily observe modulation and frequencies without an RF power tap, or wiping out your oscilloscope input channel from overvoltage.

Leroy  AD6LH


david vanhorn
 

Ok.. Intermittent oscillation may explain it all


On Tue, Jun 1, 2021, 5:02 PM Leroy Higgins <leroy.higgins@...> wrote:
Bill, does your radio have a parasitic oscillation on 6M?

Using a 100 MHz oscilloscope, tape the 10:1 probe to your RF output coax and look at the waveform with the transmitter keyed.  Should be a nice clean sine wave of your transmit frequency.  If a parasitic is present the waveform won't be a clean sine wave.   Try this method using your antenna and the dummy load.  

The last time I used this method was on a 2 kW, CW, vacuum tube test transmitter with low RF output power at 15 MHz.   The oscilloscope on the coax method indicated the RF had 60 Hz modulation caused by a power supply filter failure, in the exciter.   When the 60 Hz modulation was eliminated the Bird watt meter read the correct power.

Most coax with stranded wire braid has enough RF leakage to monitor your transmit frequency and modulation.  You can't measure transmit power level accurately, with this method, but you can easily observe modulation and frequencies without an RF power tap, or wiping out your oscilloscope input channel from overvoltage.

Leroy  AD6LH


Tom Norris
 

Tubes


On Tue, Jun 1, 2021, 9:40 AM david vanhorn <kc6ete@...> wrote:
"Fire and glass"?



On Tue, Jun 1, 2021, 9:53 AM wabate via groups.io <wabate=verizon.net@groups.io> wrote:
Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


david vanhorn
 

Ah.  Ok.   I do some torchwork with glass, and I do pretty fine smd but I don't have any tube gear.


Van
 

Did you try a different coax jumper t0 the dummy load ?

--
Sent from Outlook Email App for Android

Tuesday, 01 June 2021, 04:39PM -07:00 from Tom Norris fernblatt@...:

Tubes

On Tue, Jun 1, 2021, 9:40 AM david vanhorn <kc6ete@...> wrote:
"Fire and glass"?



On Tue, Jun 1, 2021, 9:53 AM wabate via groups.io verizon.net@groups.io> wrote:
Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


Van
 

Did you try a different coax jumper to the Dummy load?
73
Van
WD6FGB

--
Sent from Outlook Email App for Android

Tuesday, 01 June 2021, 04:39PM -07:00 from Tom Norris fernblatt@...:

Tubes

On Tue, Jun 1, 2021, 9:40 AM david vanhorn <kc6ete@...> wrote:
"Fire and glass"?



On Tue, Jun 1, 2021, 9:53 AM wabate via groups.io verizon.net@groups.io> wrote:
Hi All,

After using my 7000  for years Murphy has shown up but in a way that defies my logic.  I typically do not use it on 6M.  I was testing on 6M and i twas receiving well.  Went to transmit (RTTY mode) full carrier but was only getting 20 watts out and the SWR was max.  Checked the antenna with another rig and the antenna was fine.  Put a dummy load on the 700 and got the same low output and high SWR.  Puzzled, I tried another dummy and got the same result.  Power was measured with my Bird meter. 

This is the goofy part.  Went back to the antenna and maybe one out of three key downs the output went to 80 W and a decent SWR,  Could not duplicate that anomaly with the dummy load.  Thought maybe the antenna relay was intermittent so I tried HF and got full output and low SWR into the dummy load.  Did not try UHF. 


My guess is the SWR sensing circuit is faulty.    Is the 6M SWR sensing circuitry different from HF?  I'm a fire and glass guy so limited on what I can do with SMD.


Comment?


73 and TIA,


Bill, K3PGB


Dan Fisher AI4GK
 

I'm guessing he's a tube guy. (Fire & glass).


wabate
 

Hi Van,

Yes, Since the same coax and dummy load worked on HF,  6M should not have made a difference but, thinking as you did, I changed coax and dummy load anyway with the same result.

73,
Bill, K3PGB