I'll give that a try.

Thanks,

Barry - N4BUQ

I'd try just adding a small cap across the xtal or from xtal to ground, or across the trimmer.

280Hz isn't far, I'd try 5-10pf maybe.

?

73,

Gary

WB6OGD

I'd try just adding a small cap across the xtal or from xtal to ground, or across the trimmer.

280Hz isn't far, I'd try 5-10pf maybe.

?

73,

Gary

WB6OGD

From: "Steve Wedge, W1ES/4 via groups.io" <w1es@...>
To: "DRAKE-RADIO" <[email protected]>
Sent: Wednesday, April 23, 2025 11:26:57 AM
Subject: Re: [DRAKE-RADIO] 9 MHz Crystal in a TR-4

I'm still looking into my TR-4's 9 MHz oscillator. Earlier, I said I could wrap a coil of wire around the oscillator tube (V16) and measure the frequency but apparently I was misremembering something because I tried that last night and I could not get the counter to trigger on anything close to 9 MHz so I just used a 10:1 oscilloscope probe which worked fine.

Unfortunately, I am not able to get the oscillator exactly on 9 MHz. C130 will adjust it down to about 9.000280 MHz but I presume I should be able to swing the oscillator very slightly above and below 9 MHz leading me to believe the crystal has "drifted" upwards just a bit and because of this, I'm not quite able to get one of the filters to respond correctly. IIRC, the LSB filter will respond down to inaudible as I approach zero-beat with the calibrator; however, USB fades out long before zero-beat and I think that's due to the CO being too high.

Any suggestions on a fix? I presume baking it might bring it back down but if that doesn't work, then I'd like to replace it. They're available new in that form factor (HC-49) but I'm not sure about what other characteristics I'd need to consider. I presume this isn't a series crystal and should have an appropriate load capacitance but perhaps other factors may need to be considered.

Anyone know the specs for that crystal?

Thanks,
Barry - N4BUQ

On Apr 22, 2025, at 7:06?PM, Stan Gammons via groups.io <buttercup11421@...> wrote:

? Perhaps Mike meant the resistance went to infinity, not zero??


73

Stan
KM4HQE

On 4/21/25 22:39, Gary Follett via groups.io wrote:

There is a big disconnect in logic here.

How can any 160 ohm resistance drop to zero when you unplug ANY board?

Check your work…

Gary?

W0DVN

On Apr 21, 2025, at 8:18?PM, Mike Davidsohn G3ZCC via groups.io <mike@...> wrote:

?

Hi everyone.

Haven't had much time for the TR7 due to ill health.

However I have the transistor for the 10R line.

I wondered what caused it to blow in the first place.

I checked the 10R line,for resistance to earth with the test leads in both directions.

It read 160 ohms.

It looked a little low so I pulled,a few boards which used,the l8ne.

if/audio, if filter, switch and 2nd mixer.

One pulling the second mixer the resistance went to zero.

Tried,another board and it was the same.

No wanting to blow the transistor does anyone know if that resistance is correct?

Thanks

Mike

G3ZCC

?

?

?

?

There is a big disconnect in logic here.

How can any 160 ohm resistance drop to zero when you unplug ANY board?

Check your work…

Gary?

W0DVN

On Apr 21, 2025, at 8:18?PM, Mike Davidsohn G3ZCC via groups.io <mike@...> wrote:

?

Hi everyone.

Haven't had much time for the TR7 due to ill health.

However I have the transistor for the 10R line.

I wondered what caused it to blow in the first place.

I checked the 10R line,for resistance to earth with the test leads in both directions.

It read 160 ohms.

It looked a little low so I pulled,a few boards which used,the l8ne.

if/audio, if filter, switch and 2nd mixer.

One pulling the second mixer the resistance went to zero.

Tried,another board and it was the same.

No wanting to blow the transistor does anyone know if that resistance is correct?

Thanks

Mike

G3ZCC

?

?

?

?

Yes, I realized that counters were not common at all in that time period.? I was thinking, though, that the procedure was more to get the CO centered between the filters instead of using the filters to get the CO as close to 9 MHz as practically possible at the time.

If one filter (or both filters) has drifted, then that will affect the fidelity of the transmitted audio in SSB for whichever side-band is selected, correct?

Thanks,

Barry - N4BUQ

---

From: "Steve Wedge, W1ES/4 via groups.io" <w1es@...>
To: "DRAKE-RADIO" <[email protected]>
Sent: Tuesday, April 22, 2025 6:21:17 AM
Subject: Re: [DRAKE-RADIO] 9 MHz Alignment

Yes, right at the crystal frequency. The reason for setting by sound was because when these procedures were written for the owner in 1963 — and thereafter for the life of the 3/4 Line, very few amateurs had the money or the space for a frequency counter or a receiver that could calibrate to that sort of precision.?

Later sets like the TR5 and TR7, as well as Kenwood Hybrids had all written their procedures to set oscillators by reading with a counter. By the mid 1970s, counters were much more available, though still somewhat expensive.?

I may have had hearing good enough to tell the difference but it gets harder as I age.?

Less-expensive rigs like even the IC-7300 would appear miraculous to a ham of 1963

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Mon, Apr 21, 2025 at 18:04, n4buq < n4buq@...> wrote:

Maybe I'm misunderstanding, but are you just setting the CO to 9.000000 MHz?? I was thinking that even though it is spot on 9 MHz, that isn't good enough and it is necessary to move it so that it centered between the centers of both filters' response curves.? Is that incorrect?? I think I've done virtually the same thing by just running a loop around the CO tube (V16) to my counter but I'm not sure that gets things where they should be due to variances in the two filters.? Maybe I'm wrong.

Thanks,

Barry - N4BUQ

With the ‘7610, if you set the mice to CW, the actual receive frequency is the centre line in the display — thus avoiding the need to listen for two tones to sound the same.?

I disconnect my antenna from the HF terminal of the 7610 and run some coax venom the rig over to the transmitter or transceiver and tune the 7610 to 9.000000 MHz with a test cable with about 6” of exposed wire. ?This wire is more than long enough to “sniff” the CO even from a few inches away. ?Because that test lead isn’t directly connected or even closely-coupled to the CO, it doesn’t pull the output of the CO. It’s easy to then adjust the ceramic variable capacitor to get it on-frequency. This works with 9 MHz and also works when adjusting for 5.645000 in a T-4(any). Just adjust the 7610 for the desired frequency.

Other rigs with spectrum displays may need different offsetting techniques. ?In some displays, like Elecraft, you may need to put a marker at the desired frequency and tune for the centre of the carrier oscillator. ?The Icom doesn’t allow for markers (I believe) but in CW, the centre line is on the frequency of the readout.

I probably shouldn’t use 6-digit resolution but that’s what my display is capable of showing and it’s almost certainly more than close enough with crystal oscillators.

73,

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

On Mon, Apr 21, 2025 at 10:19 AM, Evan via groups.io < k9sqg@...> wrote:

A spectrum display can be useful for finding gaps for scheduling a QSO or calling CQ. ?Too, when contesting or looking for a QSO it helps to find the active stations.

On Monday, April 21, 2025 at 09:46:47 AM EDT, n4buq <n4buq@...> wrote:

I'm not familiar with the IC-7610 but it sounds like it has a spectrum display ("panadapter" in vintage Kenwood-speak)?? If so, what are you looking for in the display?? I guess I'm just not understanding how seeing CW on a spectrum analyzer helps.? Are you switching from LSB and USB and watching for an even offset from center?

Unfortunately, I don't have any type of SA. :-(

Thanks,

Barry - N4BUQ

I believe the filters have drifted some; I never hear them sounding exactly the same, either.?

I use my IC-7610 to set the CO now. Set for CW, send a wire out from its ant connector and look at the CO on the spectrum display.?

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Sun, Apr 20, 2025 at 22:18, n4buq < n4buq@...> wrote:

When I attempt to set the 9 MHz oscillator by listening to the sidebands (per the manual), each sideband sounds "different". It's as if I can get the "frequency" of the sound the same but the bandwidth of the sound is different. It's as if one sideband's filter is narrower than the other one. Does that make sense? I presume it's possible and that one or the other filter's shape is different (i.e. a narrower bell-shape than the other one). If that's the case, then is it an indication that there's something wrong with one (or both) filter that's making them sound different in this way.

I know that may sound like a weird explanation of what I'm hearing but it's about the best I can describe it.

BTW, 40M seemed terrible at my QTH today. I was hoping I'd hear the net with my TR-4 but I could just barely hear anyone today.

Thanks,
Barry - N4BUQ

From: "Steve Wedge, W1ES/4 via groups.io" <w1es@...>
To: "DRAKE-RADIO" <[email protected]>
Sent: Tuesday, April 22, 2025 6:21:17 AM
Subject: Re: [DRAKE-RADIO] 9 MHz Alignment

Maybe I'm misunderstanding, but are you just setting the CO to 9.000000 MHz?? I was thinking that even though it is spot on 9 MHz, that isn't good enough and it is necessary to move it so that it centered between the centers of both filters' response curves.? Is that incorrect?? I think I've done virtually the same thing by just running a loop around the CO tube (V16) to my counter but I'm not sure that gets things where they should be due to variances in the two filters.? Maybe I'm wrong.

Thanks,

Barry - N4BUQ

With the ‘7610, if you set the mice to CW, the actual receive frequency is the centre line in the display — thus avoiding the need to listen for two tones to sound the same.?

I disconnect my antenna from the HF terminal of the 7610 and run some coax venom the rig over to the transmitter or transceiver and tune the 7610 to 9.000000 MHz with a test cable with about 6” of exposed wire. ?This wire is more than long enough to “sniff” the CO even from a few inches away. ?Because that test lead isn’t directly connected or even closely-coupled to the CO, it doesn’t pull the output of the CO. It’s easy to then adjust the ceramic variable capacitor to get it on-frequency. This works with 9 MHz and also works when adjusting for 5.645000 in a T-4(any). Just adjust the 7610 for the desired frequency.

Other rigs with spectrum displays may need different offsetting techniques. ?In some displays, like Elecraft, you may need to put a marker at the desired frequency and tune for the centre of the carrier oscillator. ?The Icom doesn’t allow for markers (I believe) but in CW, the centre line is on the frequency of the readout.

I probably shouldn’t use 6-digit resolution but that’s what my display is capable of showing and it’s almost certainly more than close enough with crystal oscillators.

73,

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

On Mon, Apr 21, 2025 at 10:19 AM, Evan via groups.io < k9sqg@...> wrote:

A spectrum display can be useful for finding gaps for scheduling a QSO or calling CQ. ?Too, when contesting or looking for a QSO it helps to find the active stations.

On Monday, April 21, 2025 at 09:46:47 AM EDT, n4buq <n4buq@...> wrote:

I'm not familiar with the IC-7610 but it sounds like it has a spectrum display ("panadapter" in vintage Kenwood-speak)?? If so, what are you looking for in the display?? I guess I'm just not understanding how seeing CW on a spectrum analyzer helps.? Are you switching from LSB and USB and watching for an even offset from center?

Unfortunately, I don't have any type of SA. :-(

Thanks,

Barry - N4BUQ

I believe the filters have drifted some; I never hear them sounding exactly the same, either.?

I use my IC-7610 to set the CO now. Set for CW, send a wire out from its ant connector and look at the CO on the spectrum display.?

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent from for iOS

On Sun, Apr 20, 2025 at 22:18, n4buq < n4buq@...> wrote:

When I attempt to set the 9 MHz oscillator by listening to the sidebands (per the manual), each sideband sounds "different". It's as if I can get the "frequency" of the sound the same but the bandwidth of the sound is different. It's as if one sideband's filter is narrower than the other one. Does that make sense? I presume it's possible and that one or the other filter's shape is different (i.e. a narrower bell-shape than the other one). If that's the case, then is it an indication that there's something wrong with one (or both) filter that's making them sound different in this way.

I know that may sound like a weird explanation of what I'm hearing but it's about the best I can describe it.

BTW, 40M seemed terrible at my QTH today. I was hoping I'd hear the net with my TR-4 but I could just barely hear anyone today.

Thanks,
Barry - N4BUQ

On Apr 21, 2025, at 8:18?PM, Mike Davidsohn G3ZCC via groups.io <mike@...> wrote:

?

Hi everyone.

Haven't had much time for the TR7 due to ill health.

However I have the transistor for the 10R line.

I wondered what caused it to blow in the first place.

I checked the 10R line,for resistance to earth with the test leads in both directions.

It read 160 ohms.

It looked a little low so I pulled,a few boards which used,the l8ne.

if/audio, if filter, switch and 2nd mixer.

One pulling the second mixer the resistance went to zero.

Tried,another board and it was the same.

No wanting to blow the transistor does anyone know if that resistance is correct?

Thanks

Mike

G3ZCC

?

?

?

?