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Re: SP75 with Heil mic

 

¿ªÔÆÌåÓý

Not sure if this has anything to do with what you guys are discussing.? I use a Heil pro set (ps-6) boom mic headset with my SP75 . I've installed a Heil xt-1 microphone audio transformer in a switch box so I can switch between my head set for contesting and a shure 444d for rag chewing. The headset goes through the XT-1 matching transformer (low impedance headset to high impedance out to input to SP75). 444d goes straight through because it is high impedance already. I also use a dedicated power supply for my SP75's and not the PS7. Have always gotten great audio report's with both the boom mic and desk mic. I have tried the boom mic straight to the SP75 and found it would not drive it near as good as going through the matching transformer. Not sure if this helps, just thought I'd throw that in .Howard VE7IGA?






-------- Original message --------
From: "K6OXN Bob via groups.io" <bobk6oxn@...>
Date: 2025-03-27 6:59 p.m. (GMT-08:00)
Subject: Re: [DRAKE-RADIO] SP75 with Heil mic

The audio when I was using the Heil Goldline would cause the PS7 to trip, so I thought it was possible overdriving the transmitter. Of course the Amp was online but without the TR7 the amp didn't matter.? I did ground the SP75 to my common station ground and have cured the PS7 trip problem. Still did not have good audio with the Heil, so broke out my old standby 7077 Drake mic.? Great sounding as I recorded myself on an SDR and I am getting positive response on the audio signal from many stations.? Can't beat the old standby's and grounding is a good thing. Will leave it the way it is for now. Thanks for the responses and assist.? Running the L7 on low power is giving me a very good signal about 200 miles as S9+20.? That's good enough for me and doesn't work the amp too hard.
?
Bob
Re: SP75 with Heil mic

 

The audio when I was using the Heil Goldline would cause the PS7 to trip, so I thought it was possible overdriving the transmitter. Of course the Amp was online but without the TR7 the amp didn't matter.? I did ground the SP75 to my common station ground and have cured the PS7 trip problem. Still did not have good audio with the Heil, so broke out my old standby 7077 Drake mic.? Great sounding as I recorded myself on an SDR and I am getting positive response on the audio signal from many stations.? Can't beat the old standby's and grounding is a good thing. Will leave it the way it is for now. Thanks for the responses and assist.? Running the L7 on low power is giving me a very good signal about 200 miles as S9+20.? That's good enough for me and doesn't work the amp too hard.
?
Bob
Re: PTO makes scraping sound

 

"I think there is also a related tip on this matter in the IN still available from our good old friend DL7MAJ (sk)."
?
What is "IN"?
Mark
Re: PTO snap ring

 

Thanks Peter! I just purchased the set that Stan recommended and hopefully that will work.
Mark
Re: PTO snap ring

 

Thanks Stan I just bought it and it was the last pair. It says it comes Saturday. Perfect!
Mark
Re: SP75 with Heil mic

 

Well, you mentioned the amplifier so that implied RFI. Otherwise the amplifier is irrelevant to the operation of the SP75. What exactly is happening to your audio?

On Thu, 27 Mar 2025 09:30:41 -0700
"K6OXN Bob via groups.io" <bobk6oxn@...> wrote:

I am not suspecting RFI.? I have already done the Heil mod for the ground, I am thinking I might need to do the ground of the SP75 direct to the TR7 and see if that helps.
--

73

-Jim
NU0C
Re: PTO snap ring

 

On 3/27/25 16:57, Mark N2DMI via groups.io wrote:
There is a "snap ring" that holds the hex nut in place located on the
shaft of the PTO. The 2 holes (in the snap ring clip) seem smaller
than the standard size.
I purchased an entire snap ring set that came with the
internal/external plies but the pliers are too large for the holes.
The new snap rings should fit (?) It's just getting that snap ring off
of there that I can't seem to figure out?
I want to pull out the PTO this Saturday or Sunday so I want to get
the correct ones from Amazon quickly.
Does anyone know what pliers I need because I know someone out there
must had done this in the past.
Tnx!
Mark
I have this set which I think I bought locally.? It has several
different size tips.



73

Stan
KM4HQE
Re: PTO snap ring

 

Mark:

I have had my snap ring pliers set a long time, and it had a small diameter set that fits that snap ring.? I may be home again this weekend and can measure mine.

73
Peter
VE7PS

On Thu, Mar 27, 2025 at 2:57?PM Mark N2DMI via <markkiziuk1=[email protected]> wrote:
There is a "snap ring" that holds the hex nut in place located on the shaft of the PTO. The 2 holes (in the snap ring clip) seem smaller than the standard size.
I purchased an entire snap ring set that came with the internal/external plies but the pliers are too large for the holes. The new snap rings should fit (?) It's just getting that snap ring off of there that I can't seem to figure out?
I want to pull out the PTO this Saturday or Sunday so I want to get the correct ones from Amazon quickly.
Does anyone know what pliers I need because I know someone out there must had done this in the past.
Tnx!
Mark
PTO snap ring

 

There is a "snap ring" that holds the hex nut in place located on the shaft of the PTO. The 2 holes (in the snap ring clip) seem smaller than the standard size.
I purchased an entire snap ring set that came with the internal/external plies but the pliers are too large for the holes. The new snap rings should fit (?) It's just getting that snap ring off of there that I can't seem to figure out?
I want to pull out the PTO this Saturday or Sunday so I want to get the correct ones from Amazon quickly.
Does anyone know what pliers I need because I know someone out there must had done this in the past.
Tnx!
Mark
Re: SP75 with Heil mic

 

I am not suspecting RFI.? I have already done the Heil mod for the ground, I am thinking I might need to do the ground of the SP75 direct to the TR7 and see if that helps.
Re: Is a TR-3 Plate Choke usable in a TR-4 ?

 

In most of my dealings with TR-3's, I have found that the parts that are in common with the two (except the finals) are identical.? From a manufacturing standpoint, it makes much sense: why spec completely new / different parts when the existing ones work fine?? Yes, there can be differences (the PTO, 12JB6 vs 6JB6) but the other parts should be the same.

There was a previous question about swapping relays and I'm not sure about that one because the TR-4 switches a MUTE and an EXT RCVR that the TR-3 doesn't.? Trust but verify.? (BTW, if you find that the relay is the same or different, for sure, please let the group know for posterity).

Main differences, functionally, are several:
  • 12JB6 vs 6JB6 finals
  • Tube vs solid state PTO
  • Addition of the switching, connectors and side switch for use with external receiver
  • Sidetone
  • PA cage -- open vs. closed
  • tube variations.
I would be comfortable with the RF chokes being identical, along with probably 98+% of the parts that are in common.? The tube lineup from the TR-3 to the TR-4Cw RIT is amazingly stable from 1963 to 1978.? The overall design is even more stable.

73,

Steve Wedge, W1ES

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

Sent with secure email.

On Thursday, March 27th, 2025 at 12:48 AM, Steve KL7JT via groups.io <radiorobots@...> wrote:

Are there any dimensional or other differences?
?
Thanks for any experiential comments.
Is a TR-3 Plate Choke usable in a TR-4 ?

 

Are there any dimensional or other differences?
?
Thanks for any experiential comments.
Re: SP75 with Heil mic

 

Just about any mic should work well with the SP75. Are you suspecting RFI from the amp? One thing you can try is, despite what the manual says, try adding a ground strap from the SP75 to the TR7 chassis, and also a strap from the amp from the TR7. Also modify your mic plugs to connect the cable shield to the connector shell as described in Heil's tech note:

"Shielding of the Mic Connector

We, here in the Heil Sound lab, have discovered a very interesting fact. Most of the major transceivers
today do NOT ground their microphone shields! That¡¯s correct ¨C the mic connector shields FLOAT! Now
wasn¡¯t this one of the FIRST things we learned about building RF transmitters with speech audio sections?
GROUND those shields!! So, we came up with a very simple fix that just about anyone can make to their
rig. You don¡¯t have to get inside the radio, so you don¡¯t void any warranties. The fix is simple and effective.
This applies to the 4 and 8 pin Foster (that¡¯s the Japanese company that builds those dang little mic
connectors!!) microphone connectors so common on today¡¯s rigs.

First, unplug your Heil (what ¨C you don¡¯t have one yet??) microphone cable from the front panel of the
transceiver. Do this first, because you don¡¯t want the mic plug connected to the sensitive circuitry inside the
radio while you¡¯re soldering.

Remove the two small #4 Phillips head screws and the cable clamp they hold. Then remove the tiny Phillips
head screw that holds the rest of the metal sleeve. Slide that back onto the mic cable. Now, cut off the end of
a resistor, or get a piece of #20 solid, tinned wire about 3¡å long. Locate the mic pin that has the shield of
the mic cable soldered to it.

With a small iron, carefully solder this solid wire to that shield and pin. Bring the sleeve back up the cable
and attach to the connector with the small screw. This leaves the solid wire coming out the back of the
connector. Replace the cable clamp, and (as you do that), tightly wrap that solid wire around one of the #4
Phillips head screws and tighten the clamp assembly very well.

What you have accomplished is grounded the shield to the transceivers chassis ground through the ring on
the mic connector. (Make sure that ring is tight). This has been a big help to many stations with RFI
problems and should help you clean up your signal."



This is a variant of the "Pin 1 problem" as described by K9YC. You will want to set the levels of the SP75 exactly as described in the manual with the barefoot TR7. I was changing mics up so much that I came up with this solution to the inconvenience in adjusting the levels:

/g/DRAKE-RADIO/album?id=201880


On Wed, 26 Mar 2025 19:33:46 -0700
"K6OXN Bob via groups.io" <bobk6oxn@...> wrote:

My question is, is there a mod to the SP75 if you are using a Heil Mic on the TR7?? I am getting some problems with Audio and TX on my station that I installed an SP75 with a Heil Goldline mic.? The amp is an L7 that is very stable with the SP75 out of the circuit.? Any comments are most welcome.

Bob
--

73

-Jim
NU0C
Re: How to store unused radios?

 

Desiccant, aka...silica gel? ?works superb.? It absorbs 40% of it's weight in water.? as noted it can be dried out in a 150m F oven.?
SP75 with Heil mic

 

My question is, is there a mod to the SP75 if you are using a Heil Mic on the TR7?? I am getting some problems with Audio and TX on my station that I installed an SP75 with a Heil Goldline mic.? The amp is an L7 that is very stable with the SP75 out of the circuit.? Any comments are most welcome.
?
Bob
Re: PTO makes scraping sound

 

Thanks Bill but I just ordered a complete set off of Amazon with overnight delivery.
Mark
Re: 42.5 and 43.6 Mhz crystals

 

Gary hold onto that for now because I already ordered the crystals through two other sellers.
Mark
Re: 42.5 and 43.6 Mhz crystals

 

Just looked at my stock and I put the ones I had into my TR-4Cw RIT.


Steve Wedge, W1ES

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

Sent with secure email.

On Wednesday, March 26th, 2025 at 6:51 PM, Gary Follett via groups.io <xntrick1948@...> wrote:

I have a 43.6 MHz crystal.

$15 mailed.

Gary

W0DVN

On Mar 25, 2025, at 2:15?PM, Mark N2DMI via groups.io <markkiziuk1@...> wrote:

In the TR-4CW/RIT that I just purchased, both the 42.5 and the 43.6 Mhz crystals are missing.
Anyone know where I can get these from?
Mark
Re: 42.5 and 43.6 Mhz crystals

 

¿ªÔÆÌåÓý

I have a 43.6 MHz crystal.

$15 mailed.

Gary

W0DVN

On Mar 25, 2025, at 2:15?PM, Mark N2DMI via groups.io <markkiziuk1@...> wrote:

In the TR-4CW/RIT that I just purchased, both the 42.5 and the 43.6 Mhz crystals are missing.
Anyone know where I can get these from?
Mark
Re: 42.5 and 43.6 Mhz crystals

 

Thanks for the props!

I didn't check today when I was down in the shack.? I don't think I have any good xtals for those ranges...

Steve Wedge, W1ES

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

Sent with secure email.

On Wednesday, March 26th, 2025 at 5:02 PM, Mark N2DMI via groups.io <markkiziuk1@...> wrote:

Steve, I got an email back from Steve WD8DAS from AF4K crystals and he said he has it in stock.
I also mentioned to him that you are the one who suggested the site to me.
73's Mark
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