开云体育

I have uploaded both versions here:

/g/DRAKE-RADIO/files/R7%20Files

On Sun, 27 Apr 2025 16:38:53 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:

> OK... I have done some searching and found the TR7 files.? Does anyone on
> here know if there were different versions of the R7 power supply board,
> not the 13.8v board, but the power supply board.? I have an earlier version
> R7 and its power supply board is different from the one shown in the
> service manual.
>
> Thanks.
>
> Dan (W3DF)

--

73

-Jim
NU0C

On Sun, 27 Apr 2025 23:15:00 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:

> My service manual shows the newer version of the power supply board, but
> the board in my R7 has the two bipolar transistors, I think I need the
> schematic for the older version.
> The board in my R7 appears to be modified but I'm not sure since I don't
> have the schematic, it has components on both sides of the board.

Both versions can be found at the link I posted earlier. Added components are not uncommon on Drake boards.

/g/DRAKE-RADIO/files/R7%20Files

I am attaching a pictorial of the early board.

> Are the two versions plug-in compatible?

Yes.

> I have the newer power supply
> board that I purchased and the regulator board also.? When I plug in the
> regulator board I purchased, the R7 motorboats.? It looks identical to the
> one I have in the R7 that works.? Guess it has a bad component(s).

That is the risk of buying used boards. Now you have another board to repair. Motorboarding is indicative of a failing capacitor. The R7 power supply section is known to be a high heat area when run from 120VAC.

> One other thing... I cannot get the power supply board to pull out, it only
> pulls up a little bit then stops.? I don't know what is stopping it, I
> don't think it's the pass transistors on the side wall.
> I don't want to force it and break something.

It should pull straight up and out but it it has never been removed the Molex connectors could be still very tight.

The old version board should have C1908 (220uF) replaced. That can solve some strange problems. The new version will need all the 10uF caps in the output of the TDA-2002 and the voltage multiplier and the 1uF on the input of the regulator replaced. They have all likely seen life, or close to it. Again, use NEW high quality 105C parts/

--

73

-Jim
NU0C

Yes... I replaced the 220 uf on both the regulator board and the power supply board today.? I am also going to replace the?4700 uf capacitor.? Changing the 220s did not change any of the voltages... still 11.8v instead of 13.8v and 11v instead of 10v.? The caps run warm, especially?the 220 uf on the power supply board, it gets a little hot. I cannot get the voltages right with the adjustment pots.? I checked the resistors on the regulator board and they are OK and I think the pot is OK too.? I turn it fully clockwise to get 11.8v.? Does line voltage affect this much?? I'm running it on 115vac? Since I cannot get the power supply board out I cannot get to the resistors.

Yes...? the power supply board does pull straight up, but only about an 1/8 inch, then it won't go any farther.? I checked for interference but didn't see any.

Are the old and new version power supply boards plug-in compatible?

The R7 works fine the way it is, but there is one strange problem... on the BC band switch positions I hear this randomly wandering heterodyne on several spots on the dial that interferes with?weaker?BC signals.? Sometimes it will wander off to another frequency.

I had WB4HFN go over this R7, but he did not find all the problems.

73, Dan (W3DF)

On Sun, Apr 27, 2025 at 11:56?PM Jim Shorney via <jimNU0C=[email protected]> wrote:

On Sun, 27 Apr 2025 23:15:00 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:

> My service manual shows the newer version of the power supply board, but
> the board in my R7 has the two bipolar transistors, I think I need the
> schematic for the older version.
> The board in my R7 appears to be modified but I'm not sure since I don't
> have the schematic, it has components on both sides of the board.

Both versions can be found at the link I posted earlier. Added components are not uncommon on Drake boards.

/g/DRAKE-RADIO/files/R7%20Files

I am attaching a pictorial of the early board.

> Are the two versions plug-in compatible?

Yes.

> I have the newer power supply
> board that I purchased and the regulator board also.? When I plug in the
> regulator board I purchased, the R7 motorboats.? It looks identical to the
> one I have in the R7 that works.? Guess it has a bad component(s).

That is the risk of buying used boards. Now you have another board to repair. Motorboarding is indicative of a failing capacitor. The R7 power supply section is known to be a high heat area when run from 120VAC.

> One other thing... I cannot get the power supply board to pull out, it only
> pulls up a little bit then stops.? I don't know what is stopping it, I
> don't think it's the pass transistors on the side wall.
> I don't want to force it and break something.

It should pull straight up and out but it it has never been removed the Molex connectors could be still very tight.

The old version board should have C1908 (220uF) replaced. That can solve some strange problems. The new version will need all the 10uF caps in the output of the TDA-2002 and the voltage multiplier and the 1uF on the input of the regulator replaced. They have all likely seen life, or close to it. Again, use NEW high quality 105C parts/

--

73

-Jim
NU0C

Thanks for the info Jim.

Dan (W3DF)

On Mon, Apr 28, 2025 at 12:58?AM Daniel W3DF via <danflan49=[email protected]> wrote:

Yes... I replaced the 220 uf on both the regulator board and the power supply board today.? I am also going to replace the?4700 uf capacitor.? Changing the 220s did not change any of the voltages... still 11.8v instead of 13.8v and 11v instead of 10v.? The caps run warm, especially?the 220 uf on the power supply board, it gets a little hot. I cannot get the voltages right with the adjustment pots.? I checked the resistors on the regulator board and they are OK and I think the pot is OK too.? I turn it fully clockwise to get 11.8v.? Does line voltage affect this much?? I'm running it on 115vac? Since I cannot get the power supply board out I cannot get to the resistors.

Yes...? the power supply board does pull straight up, but only about an 1/8 inch, then it won't go any farther.? I checked for interference but didn't see any.

Are the old and new version power supply boards plug-in compatible?

The R7 works fine the way it is, but there is one strange problem... on the BC band switch positions I hear this randomly wandering heterodyne on several spots on the dial that interferes with?weaker?BC signals.? Sometimes it will wander off to another frequency.

I had WB4HFN go over this R7, but he did not find all the problems.

73, Dan (W3DF)

On Sun, Apr 27, 2025 at 11:56?PM Jim Shorney via <jimNU0C=[email protected]> wrote:

On Sun, 27 Apr 2025 23:15:00 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:

> My service manual shows the newer version of the power supply board, but
> the board in my R7 has the two bipolar transistors, I think I need the
> schematic for the older version.
> The board in my R7 appears to be modified but I'm not sure since I don't
> have the schematic, it has components on both sides of the board.

Both versions can be found at the link I posted earlier. Added components are not uncommon on Drake boards.

/g/DRAKE-RADIO/files/R7%20Files

I am attaching a pictorial of the early board.

> Are the two versions plug-in compatible?

Yes.

> I have the newer power supply
> board that I purchased and the regulator board also.? When I plug in the
> regulator board I purchased, the R7 motorboats.? It looks identical to the
> one I have in the R7 that works.? Guess it has a bad component(s).

That is the risk of buying used boards. Now you have another board to repair. Motorboarding is indicative of a failing capacitor. The R7 power supply section is known to be a high heat area when run from 120VAC.

> One other thing... I cannot get the power supply board to pull out, it only
> pulls up a little bit then stops.? I don't know what is stopping it, I
> don't think it's the pass transistors on the side wall.
> I don't want to force it and break something.

It should pull straight up and out but it it has never been removed the Molex connectors could be still very tight.

The old version board should have C1908 (220uF) replaced. That can solve some strange problems. The new version will need all the 10uF caps in the output of the TDA-2002 and the voltage multiplier and the 1uF on the input of the regulator replaced. They have all likely seen life, or close to it. Again, use NEW high quality 105C parts/

--

73

-Jim
NU0C

On Mon, 28 Apr 2025 00:58:03 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:

> Yes... I replaced the 220 uf on both the regulator board and the power
> supply board today.? I am also going to replace the 4700 uf capacitor.
> Changing the 220s did not change any of the voltages... still 11.8v instead
> of 13.8v and 11v instead of 10v.? The caps run warm, especially the 220 uf
> on the power supply board, it gets a little hot. I cannot get the voltages
> right with the adjustment pots.? I checked the resistors on the regulator
> board and they are OK and I think the pot is OK too.? I turn it fully
> clockwise to get 11.8v.? Does line voltage affect this much?? I'm running
> it on 115vac? Since I cannot get the power supply board out I cannot get to
> the resistors.


The 220uF on the PS board will run warm because it is essentially filtering square wave ripple from the mutltivibrator oscillator. That's why I recommend a high quality 105C cap. Harder to find in axial, but possible. I would use a 35V part.

It almost sounds like something is drawing too much current. Do you have a scope? If so, check for excessive ripple at the output of the bridge rectifier. The variable regulators on both boards are bog standard 723 circuits which are mature technology. Barring component value drift you should be able to dial in the voltages with no trouble. As has been said, check your Molex connectors thoroughly. Unplug the Power Supply board and see if you can adjust the Regulator to spec. You can also try running the rig from external DC and see if you can net the +10v.


> Are the old and new version power supply boards plug-in compatible?

Yes.

> The R7 works fine the way it is, but there is one strange problem... on the
> BC band switch positions I hear this randomly wandering heterodyne on
> several spots on the dial that interferes with weaker BC signals.
> Sometimes it will wander off to another frequency.

That could be spurs from the 23 KHz multivibrator oscillator on the PS board. Usually they are about 23 KHz apart and will wander a bit.

I am attaching the PS board BOM per your request. I did notice one thing I had not seen before. My R7A has the late version board so I had not looked at the early board much. There is an added capacitor on the schematic that is not present on the TR7 version of this board, C1919. It is shown as a 1000uF from the primary center tap of the transformer to ground. It is NOT listed on the BOM on shown in the pictorial. Which makes me want to open up another R7 so see what is there. If you do have that capacitor it should he replaced as well by the same logic as C1908, as it has been worked hard. If you don't have it, don't worry about it at this point. It is either a late addition or an artifact of a part that was removed from the build. We don't know which at this point and TR7 boards seem to work fine without it.

It is also worth noting that the PS board has two independent ground circuits which connect to the parent board. You have one ground for +10/+5, and another for the +24/-5. Check both.

--

73

-Jim
NU0C

One again, yes. The two boards are interchangeable. However as I have already stated you will want to change all the small electrolytics from the output of the TDA2002 to the output of the rectifier/voltage multiplier. See attached photo of mine. That is not a gray cap in the front left. It was the same color as the others before it saw several years of continuous service. While you are at it you might want to put a 10uF from pin 1 of the LM317 to ground. It is recommended on the data sheets to improve ripple rejection and I have learned over the years that it is wise to follow such recommendations.

You may want to consider running the R7 from external DC. It will take a lot of heat out of the box.



On Mon, 28 Apr 2025 23:38:24 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:

> And a newer version power supply board.? My R7 has the older one.? Will the
> new one work in an older R7?
> I don't want to destroy anything by trying to use this newer PS board.


--

73

-Jim
NU0C